IndustriaTextila [629434]

IndustriaTextila
ISSN 1222–5347
2/2016
Recunoscutã în România, în domeniul ătiințelor inginerești, de cãtre
Consiliul Național al Cercetãrii ătiințifice din Învãțãmântul Superior
(C.N.C.S.I.S.), în grupa A /
Aknowledged in Romania, in the engineering sciences domain,
by the National Council of the Scientific Research from the Higher Education
(CNCSIS), in group A
COLEGIUL
DE REDACTIE:
Dr. ing. EMILIA VISILEANU
cerc. șt. pr. I – EDITOR ȘEF
Institutul Național de Cercetare-Dezvoltare
pentru Textile și Pielărie – București
Dr. ing. CARMEN GHIȚULEASA
cerc. șt. pr. I
Institutul Național de Cercetare-Dezvoltare
pentru Textile și Pielărie – București
Prof. dr. GELU ONOSE
cerc. șt. pr. I
Universitatea de Medicină și Farmacie
„Carol Davila“ – București
Prof. dr. ing. ERHAN ÖNER
Marmara University – Turcia
AMINODDIN HAJI
Dpartament of Textile Engineering Birjand Branch
Islamic Azad University
Birjand – Iran
Prof. dr. ing. CRIȘAN POPESCU
Institutul German de Cercetare a Lânii – Aachen
Prof. dr. ing. PADMA S. VANKAR
Facility for Ecological and Analytical Testing
Indian Institute of Technology – India
Prof. dr. MUGE YUKSELOGLU
Marmara University – Turcia
Dr. ing. FAMING WANG
Soochow University – China
University of Alberta – Canada
Prof. univ. dr. ing. CARMEN LOGHIN
Universitatea Tehnică „Ghe. Asachi“ – Iași
Ing. MARIANA VOICU
Ministerul Economiei
Prof. dr. LUCIAN CONSTANTIN HANGANU
Universitatea Tehnică „Ghe. Asachi“ – Iași
Prof. ing. ARISTIDE DODU
cerc. șt. pr. I
Membru de onoare al Academiei de Științe
Tehnice din România
Prof. uni v. dr. DOINA I. POPESCU
Academia de Studii Economice – București
Prof. dr. LIU JIHONG
Jiangnan University – ChinaGONCA BALCI KILIC, AYȘE OKUR
Comparație între proprietățile fizice ale firelor de bumbac, modale și acrilice filate în sistemele cu inele și cu capăt liber OE 81–90
STANA KOVAČEVIĆ, IVANA GUDLIN SCHWARZ, ZENUN SKENDERIDiversitatea proprietăților firelor încleiate cu și fără înmuiere prealabilă 91–98
NESMA SAOUSSEN ACHOUR, AYDA BAFFOUN, MOHAMED HAMDAOUI,
SASSI BEN NASRALLAHEfectul parametrilor de tricotare asupra capacitatii de absorbție a apei 99–102
ASIF MANGAT, LUBOS HES, VLADIMIR BAJZIK, FUNDA BUYUK
Impactul aspectului de suprafață al structurii de tricot patent din poliester asupra proprietăților termice 103–108
AMINODDIN HAJI, SAYYED SADRODDIN QAVAMNIA, FARHAD KHOSRAVI BIZHAEMVopsirea fără săruri a bumbacului cu coloranți anionici utilizând tratamentele cu plasmă și chitosan 109–113
M. İBRAHIM BAHTIYARI, HÜSEYIN BENLI
Vopsirea țesăturilor din poliamidă modificate enzimatic cu coloranți naturali 114–120
CHENGJIAO ZHANG, XIN CAI, FAMING WANGPrepararea și evaluarea peliculelor de acid poli (lactic) (PLA) cu funcție de autocurățare în amestec cu nanoparticule de dioxid de titan (TiO
2) 121–126
KADIR BILISIK, HUSEYIN OZDEMIR, GAYE YOLACAN KAYAProprietățile de rezistență la forfecare interlaminară a nanocompozitelor cu cusături multiple 127–134
VIRGIL TUDOSE, RADU FRANCISC COTERLICI, DANIELA TUDOSE, HORIA GHEORGHIU, STEFAN DAN PASTRAMAStudiu privind utilizarea unui compozit armat cu fibre de bumbac pentru obținerea căștilor de protecție 135–140
ZORAN STJEPANOVIČ, ANDREJ CUPAR, SIMONA JEVŠNIK, TANJA KOCJAN STJEPANOVIČ, ANDREJA RUDOLFConstrucția articolelor de îmbrăcăminte adaptate persoanelor cu scolioză utilizând prototiparea virtuală și metoda CASP 141–148Editatã în 6 nr./an, indexatã și recenzatã în:
Edited in 6 issues per year, indexed and abstracted in:
Science Citation Index Expanded (SciSearch®), Materials Science
Citation Index®, Journal Citation Reports/Science Edition, World Textile
Abstracts, Chemical Abstracts, VINITI, Scopus, Toga FIZ technik
ProQuest CentralRevist ãcotat ãISIși inclus ãîn Master Journal List a Institutului pentru
ătiința Inform ãrii din Philadelphia – S.U.A., începând cu vol. 58,
nr. 1/2007/
ISI rated magazine, included in the ISI Master Journal List of the Institute
of Science Information, Philadelphia, USA, starting with vol. 58, no. 1/2007
¸˘
79 industria textila 2016, vol. 67, nr. 2 ˘

80 industria textila 2016, vol. 67, nr. 2 ˘ÜGONCA BALCI KILIC
AYȘE OKUR
STANA KOVAČEVIĆ
IVANA GUDLIN SCHWARZZENUN SKENDERI
NESMA SAOUSSEN ACHOUR
AYDA BAFFOUN MOHAMED HAMDAOUI SASSI BEN NASRALLAH
ASIF MANGAT
LUBOS HES VLADIMIR BAJZIK FUNDA BUYUK
AMINODDIN HAJI
SAYYED SADRODDIN QAVAMNIAFARHAD KHOSRAVI BIZHAEM
M. İBRAHIM BAHTIYARI
HÜSEYIN BENLI
CHENGJIAO ZHANG
XIN CAI, FAMING WANG
KADIR BILISIK
HUSEYIN OZDEMIR GAYE YOLACAN KAYA
VIRGIL TUDOSE
RADU FRANCISC COTERLICI DANIELA TUDOSE HORIA GHEORGHIU STEFAN DAN PASTRAMA
ZORAN STJEPANOVIČ
ANDREJ CUPAR SIMONA JEVŠNIK TANJA KOCJAN STJEPANOVIČ ANDREJA RUDOLF81
91
99
103
109
114
121
127
135
141A comparison for the physical properties of cotton, modal and acrylic yarns spun in
ring and OE-rotor spinning systems
Diversity of spun yarn properties sized with andwithout prewetting
Effect of knitted parameters on wicking behaviours
Impact of surface profile of polyester knitted rib structure on its thermal properties
Salt free neutral dyeing of cotton with anionic dyes using plasma and chitosan treat-
ments
Dyeing of enzymatically modified polyamide fabrics with natural dyes
Preparation and evaluation of the self-cleaning poly (lactic acid) (PLA) film blended wit
Titanium dioxide (TiO2) nano particles
Interlaminar shear strength properties of multistitched preform nano composites
Study regarding the use of a cotton fiber reinforced composite for obtaining protection
helmets
Construction of adapted garments for people with scoliosis using virtual prototyping
and CASP method
EDITORIAL STAFF
Editor-in-chief: Dr. eng. Emilia Visileanu
Graphic designer: Florin Prisecaru
e-mail: visilean@ns.certex.roScientific reviewers for the papers published in this number :Contents
Journal edited in colaboration with Editura AGIR , 118 Calea Victoriei, sector 1, Bucharest, tel./fax: 021-316.89.92; 021-316.89.93;
e-mail: editura@agir.ro, www.edituraagir.roB. Ilderim – Turcia
V. Popescu – Romania
I. Dumitrescu – Romania
G. Onose – Romania
Chen Ji – China
Chao Zhi – China

INTRODUCTION
Raw material and spinning system are known to be
the most import
ant factors which determine physical
properties of yarns. Although different spinning sys-tems developed in recent years, conventional spin-ning systems (ring and OE-rotor) are still commonlyused. Ring and OE-rotor spinning systems constituteapproximately 90% of yarn production in the world[1].Many researchers have studied the effect of rawmaterials and spinning systems on yarn properties[2–8]. Mohamed et al. analyzed the hairiness anddiameter of 100% cotton, 100% polyester and cotton-polyester ring and open-end yarns and stated thatOE yarns are more bulky but less hairy than corre-
sponding ring yarns. On the other hand, they foundthat the hairiness of OE yarns have a higher coeffi-cient of variation than ring yarns [9]. Jackowska-Strumillo et al. studied the quality of cotton yarns spunusing ring-, compact-, and rotor-spinning machinesand found that the rotor yarns are characterized bylower hairiness, unevenness and tenacity [10]. Kilicand Okur investigated the effect of structural, physi-cal and mechanical properties of ring, compact andvortex spun yarns. They found that hairiness valuesof ring yarns are the highest and vortex yarns are thelowest [11]. Soe et al. investigated the structure andproperties of vortex spun yarns and compared withring and open-end rotor spun yarns. They measuredA comparison for the physical properties of cotton, modal and acrylic
yarns spun in ring and OE-rotor spinning systems
GONCA BALCI KILIC AYȘE OKUR
REZUMAT – ABSTRACT
Comparație între proprietățile fizice ale firelor de bumbac, modale și acrilice filate
în
sistemele cu inele și cu capăt liber OE
Scopul acestui studiu a fost de a analiza efectele materiei prime și ale sistemului de filare asupra proprietăților fizice ale
firelor. În acest scop, au fost analizate fire din fibre: naturale (100% bumbac), regenerate (100% modale) și sintetice(100% acrilice). Firele au fost realizate utilizând sistemele de filare cu inele și capăt liber (OE). Neuniformitatea firelor,neuniformitatea optică, imperfecțiunile, proprietățile structurale cum ar fi densitatea, CVFS% (rugozitatea), forma(rotunjimea) etc., pilozitatea, frecarea fir-fir, frecarea fir-ceramică și frecarea fir-metal au fost evaluate în scopul realiz arii
acestui studiu. La evaluarea efectului sistemelor de filare, rezultatele au arătat că valorile neuniformității,imperfecțiunilor, diametrului și rugozitatii, în cazul firelor filate cu capăt liber (OE), sunt ridicate. Pe de altă parte, s-aconstatat că valorile densității, factorului de formă, pilozității și coeficienților de frecare pentru firele filate cu capăt l iber
(OE) sunt mai mici decât în cazul firelor filate cu inele, pentru toate tipurile de materiale. Mulți cercetători afirmă căefectul materiei prime asupra proprietăților firelor este important. Cu toate acestea, în acest studiu, se remarcă faptul căvalorile neuniformității, imperfecțiunilor, pilozității și coeficienților de frecare ale firelor modale și acrilice din fibre c u
aceeași lungime și finețe sunt apropiate.
Cuvinte-cheie: fire filate cu inele, fire filate cu capăt liber, fire acrilice, fire modale, metoda Capstan, metoda cu dublă
răsucire, frecarea firului, pilozitatea firului
A comparison for the physical properties of cotton, modal and acrylic yarns spun
in ring and OE-rotor spinning systems
In this study, it was aimed to analyze the effects of raw material and spinning system on physical properties of yarns.For this purpose, natural (100% cotton), regenerated (100% Modal) and synthetic (100% acrylic) yarns were analyzed.Yarns were produced systematically in ring and open-end rotor (OE-rotor) systems. Yarn unevenness, opticalunevenness, imperfections, structural properties such as density, CVFS% (roughness), shape (roundness) etc., yarnhairiness, yarn-to-yarn friction, yarn-to-ceramic friction and yarn-to-metal friction properties were evaluated in the scopeof the study. When the effect of spinning systems is evaluated, results show that the values of unevenness,imperfections, diameter and roughness for OE-rotor yarns are higher. On the other hand, values of density, shape factor,hairiness and friction for OE-rotor yarns are found lower than ring yarns for all material types. Many researchers statethat the effect of raw material on yarn properties is important. However, in this study, it is remarkable that unevenness,imperfections, hairiness and friction values of Modal and acrylic yarns made of fibres with the same length and finenessare fairly close to each other.
Keywords: ring yarns, open-end rotor yarns, acrylic yarns, Modal yarns, Capstan method, twisted strand method, yarn
friction, yarn hairiness
81 industria textila 2016, vol. 67, nr. 2 ˘

yarn properties such as evenness, hairiness, bulki-
ness, tenacity, compression and bending propertiesand concluded that vortex yarns are stiffer than ringand open-end rotor spun yarns, while ring yarns havethe highest tenacity values [12]. Ghosh et al. investi-gated yarn-to-yarn (YY) and yarn-to-metal (YM) fric-tion coefficients of yarns which were produced in dif-ferent spinning systems (ring, rotor, air-jet, open-end,friction) by using viscose fibres. The results indicatethat in case of YM friction, ring yarns have higher fric-tion values than rotor yarns [13]. Balci Kilic and Sülarinvestigated the frictional properties of 100% cotton,100% Tencel LF, %50:50 cotton/Tencel LF blendedyarns spun in ring-, compact- and vortex-spinningsystems. Results show that the lowest YY frictioncoefficient values belong to the vortex yarns.However, the highest YM and YC friction coefficient isobserved for vortex yarns [14]. Tyagi et al. studiedthe response of cotton ring- and rotor-spun yarns tomercerization treatment. The results show that yarn-to-metal frictional coefficient of OE-rotor-spun yarnsare significantly lower than ring-spun yarns for both
mercerized and grey yarns [15]. Nair et al. also exam-
ined the relationship between physical properties andfrictional properties of cotton fibres and yarns andshowed coarser and more compressible yarns havehigher coefficients of friction values [16].Systematically spun ring and OE-rotor yarns made ofnatural (100% cotton), regenerated cellulose (100%Modal) and synthetic (100% acrylic) fibres were pre-ferred in the scope of this study. The fibre length andfibre fineness also directly affect the physical proper-ties of yarns. Most of the studies carried out to inves-tigate the yarn properties have ignored this fact. Inthis kind of studies, yarns have to contain fibres withthe same length and fineness for better comparison.For this reason, Modal and acrylic fibres with thesame length and fineness, cotton fibres have differ-ent length and fineness due to its natural structurewere used in the study. Cotton fibres were preferredas reference raw material which is traditionally usedto evaluate the effects of spinning systems.
EXPERIMENTAL WORK
Materials and methods
In this study, natural (100% cotton), regenerated
(100% Modal) and synthetic (100% acrylic) ring andOE-rotor yarns were analyzed. Properties of cotton,
Modal and acrylic fibres are given in t
able 1 and table
2. Acrylic and Modal fibres have same cut length andfineness (table 2). All yarns were produced systemat-ically in both spinning systems. The slivers that havethe same properties were used in ring and OE-rotorspinning systems. The fibres of all yarns were passedthrough the same production steps for both spinningsystems to analyze the effect of raw material andspinning system accurately. The cotton fibres passedthrough the combing process.Unevenness, imperfections, diameter, density, rough-ness, shape, hairiness and yarn friction (yarn-to-yarn,yarn-to-metal and yarn-to-ceramic) were measuredin the study. For 100% cotton yarns, the effect ofspinning system and for 100% acrylic and 100%Modal yarns that have the same fibre length and fibrefineness, also the effect of raw material were investi-gated. Moreover, yarn hairiness and yarn-to-yarn fric-tion values were measured using two different meth-ods for each. The effect of measuring method onfrictional properties of yarns is also analyzed.Unevenness, imperfections, diameter, density, rough-ness and shape values of yarns were measured byusing Uster Tester 5 S800. Every test was performedat 400 m/min test speed throughout 2.5 minutes.Hairiness value of yarns (H) was measured by usingUster Tester 5 S800 with at 400 m/min test speedthroughout 2.5 minutes. Hairiness value was alsomeasured by using Uster Zweigle Hairiness Tester 5(UZHT5) with 5 cN pretension with 50 m/min testspeed and 4 minutes test duration. The hairinessvalue of the UT5 is called H, whereas the hairiness
values of the UZHT5 is called S3. UZHT5 also mea-
sures S1+2 value. The H value is total length of pro-truding hairs per centimeters, S3value is the sum of
all protruding fibres 3 mm and longer (cumulative)and S1+2 value is the total amount of the fibres short-er than 3 mm [17–18]. Measurement of yarn-to-yarn(YY), yarn-to-metal (YM) and yarn-to ceramic (YC)friction were performed by using Lawson HemphillCTT Dynamic Friction Tester with a constant speed of100 m/min. The friction testing device used in theexperiments has a tension arm and the input tensionis set at constant value by this arm. The output ten-sion is measured by the tension meter and the frictioncoefficient is calculated by software through inputand output tensions [19]. YY, YM and YC tests were
82 industria textila 2016, vol. 67, nr. 2 ˘PROPERTIES OF COTTON FIBRES (HVI RESULTS)
Fibre fineness (micronaire) 3.6
Fibre length (mm) 29.5
Tenacity (cN/tex) 29.0
Elongation (%) 4.85
Uniformity (%) 82.5
Maturity 0.88
SFI (%) 8.50PROPERTIES OF MODAL AND ACRYLIC FIBRES
Parameters Modal Acrylic
Fineness (dtex) 1.3 1.3
Cut length (mm) 38 38
Tenacity (cN/tex) 35 30
Elongation (%) 13 35.4
Tenacity in wet state (cN/tex) 20 35.8
Elongation in wet state (cN/tex) 15 36.4Table 1 Table 2

performed by using 5 cN input tension. When the lit-
erature is examined, it could be seen that input ten-sion in knitting process ranges from 3 to 10 cN[20–22]. In this study, input tension is selected as5 cN which is equal to pretension in UZHT5.
Yarn is allowed to run over friction surfaces such asstainless steel or ceramic pin with a specified wrapangle in yarn-to-material (YM and YC) test and themethod is called “Capstan Method”. YM and YC fric-tion tests are performed with the same test fixture bychanging friction pins. The software calculates thecoefficient of yarn-to-material friction ( μ) using the
Capstan formula given in equation 1 [23]:
T
2ln (   )T1μ= (1) θ
μis the coefficient of yarn-to-material friction; T2– the
output tension; T1– the input tension; θ – the cumu-
lative wrap angle (radian) (figure 1).Yarn is wrapped around itself in YY friction test and itis named “Twisted Strand Method”. Output tension onthe yarn changes during the test and is measured bytension meter. The software calculates the coefficientof yarn friction using the input and output tension val-ues as well as the number of wraps and apex angle(figure 2). The coefficient of YY friction using the for-mula given in equation 2 [24]:
ln (T
2/T1)
μ= (2)
4π(n – 0.5) sin β/2
where μis the coefficient of YY friction; T2– the out-
put tension; T1– the input tension; βis 35ș (lower
apex angle between two yarns); and n– the number
of wraps (n  = 3).
Yarn-to-material (YM and YC) and YY friction testsare performed by different methods and the coeffi-cients of friction are calculated by different formulasas mentioned above. In the study, YY tests also per-formed with Capstan Method. Yarn is wrappedaround on fixed frictionless pulleys and cumulativewrap angle is measured (225ș) for every test in thismethod and friction coefficient of yarn is calculatedusing the Capstan Formula (figure 3). RESULTS AND DISCUSSION
In this section, effects of raw material and spinning
system on yarn properties were evaluated in terms ofunevenness, imperfections, structural properties(density
, CVFS%, shape etc.), hairiness and friction-
al properties. The test results were evaluated bySPSS 20 software to compare the main effects.Analyses of variance (ANOVA) were performed forα = 0.05 significance level
Unevenness and Imperfections
Unevenness (CVm%), optical unevenness (CV2D
0.3 mm%), values of thin places (–50 %/km), thickplaces (+50 %/km) and nep
s (+200 %/km, +280
%/km) of 100% cotton, 100% Modal, 100% acrylicring and OE-rotor yarns are given in table 3.Unevenness and optical unevenness results areshown in figure 4 and ANOVA results are shown intable 4. It is seen that the effect of spinning system isstatistically significant on both yarn unevenness andimperfections for cotton, Modal and acrylic yarns(p ≤ 0.05). The OE-rotor yarns have higher values forall parameters. When the effect of raw-material on unevenness andoptical unevenness is evaluated, it is seen that cottonyarns have the highest values for both ring and OE-rotor spinning technologies as expected (figure 4).Acrylic yarns have lower values than Modal yarns forboth ring and OE-rotor spinning technologies. Forring yarns, differences are not statistically significantbetween Modal and acrylic raw materials (p = 0.073).The number of fibres in yarn cross-section and the
83 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 3. The position of yarns during yarn-to-yarn friction
tests (Capstan method)
Fig. 1. The position of yarns during
yarn-to-material friction tests
Fig. 2. The position of yarns during yarn-to-yarn friction tests
(twisted strand method)

fibre length are the main parameters which effect
yarn unevenness [25]. In the study, Modal and acrylicfibres have the same linear densities (1.3 dtex) andfibre lengths (38 mm). This is the main factor to getstatistically the same unevenness values for Modaland acrylic yarns. For OE-rotor yarns, it is seen thatdifferences between the Modal and the acrylic rawmaterials are also statistically significant (p ≤ 0.05).The main factor for this situation is thought to be thedifferences between the spinning technologies. Inring spinning, distances between the drafting rollerstake effect for unevenness. On the other hand, inOE-rotor spinning system fibres become individualelements after opening roller and form a yarn struc-ture by the help of frictional forces in the rotor groove.Because the frictional forces between the acrylicfibres are higher, yarn formation stage is more con-trolled when the yarn is pulled out of the navel [26].If the effect of raw material on imperfections is exam-
ined, it is seen that effect of raw material is not sta-tistically significant for ring yarns in terms of thinplaces (–50 %/km), thick places (+50 %/km) and neps(+200 %/km). On the other hand, the effect of rawmaterial on imperfections is statistically significant forOE yarns. However, OE-rotor acrylic yarns havelower values of thin places (–50 %/km), thick places(+50 %/km) and neps (+200 %/km) because of theeffect of their surface properties related with friction-al forces.
Structural Parameters
Diameter (2DØ mm), density (D g/cm
3), roughness
(CV FS %) and optical shape (roundness) values of
cotton, Modal and acrylic yarns spun in ring andopen-end systems are shown in table 5 and barcharts of these parameters are shown in figures 5and 6.
84 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 4. CVm % and CV 2D 0.3 mm% values of ring and OE-rotor yarns
UNEVENNESS AND IMPERFECTION VALUES OF RING AND OE-ROTOR YARNS
ParametersRING OE-ROTOR
Cotton Modal Acrylic Cotton Modal Acrylic
Cvm% 11.40 10.82 10.63 15.32 14.12 13.36
CV2D 0.3 mm 13.19 11.95 11.78 15.26 12.94 12.28
Thin places –50% 0.0 0.0 0.8 67.5 14.2 13.8
Thick places +50% 5.8 4.6 1.3 82.9 44.6 14.2
Neps +200% 13.3 12.9 0.8 340.4 121.7 27.9
Neps +280% 1.0 0.0 0.0 15.2 6.5 11.5
ANOVA RESULTS FOR Cvm (%) AND CV2D 0.3 mm(%)
Parameters Spinning System Sum of Squares Mean Square F Sig.
Cvm (%)RING 1.967 0.983 33.713 0.000
OE-ROTOR 11.728 5.864 287.856 0.000
CV2D 0.3 (%)RING 7.180 3.590 58.356 0.000
OE-ROTOR 29.432 14.716 422.849 0.000Table 3
Table 4

Upon a general evaluation of the spinning systems,
the effect of spinning system is found to be statisti-cally significant on diameter (2DØ mm), density (D
g/cm
3), roundness (Shape) and roughness (CV FS
%) values (p ≤ 0.05). Density (D g/cm3) and round-
ness (Shape) values of ring yarns are higher than
OE-rotor yarns for all of the raw material types.Furthermore, roughness (CV FS %) and diameter(2DØ mm) values of OE-rotor yarns are higher thanring yarns. These are all due to the differencesbetween ring and OE-rotor spinning technologies.Since the fibers are located through a helical way ina ring yarn, ring yarns have denser structures thanOE-rotor yarns. This means lower diameter, but high-er density for ring yarns. In addition, helical settle-ment causes more regular and round shape for ringyarns. In terms of roughness property, rotor yarns
have higher values because of the wrapper structure.Figure 7 shows the cross-sectional images of ringand OE-rotor yarns that were processed by imageanalysis tools.The effect of raw material is also found to be statisti-cally significant on structural parameters (p ≤ 0.05)(table 6 and table 7). When a comparison is donebetween Modal and acrylic yarns, 100% Modal yarnshave lower diameter and higher density values forboth spinning systems. This would be due to thetrilobal cross-sectional shape of Modal fibres. It isthought that trilobal fibres packed closer and thiswould cause a denser structure (figure 7). Roughness (CV FS%) is CV of fine structure of ayarn and it means irregularity increase between
85 industria textila 2016, vol. 67, nr. 2 ˘STRUCTURAL PARAMETERS OF RING AND OE-ROTOR YARNS
ParametersRING OE-ROTOR
Cotton Modal Acrylic Cotton Modal Acrylic
2DØ (mm) 0.23 0.21 0.22 0.26 0.23 0.24
D (g/cm3) 0.46 0.57 0.51 0.38 0.47 0.42
CV FS (%) 8.84 8.11 7.21 10.46 8.93 8.50
Shape 0.83 0.84 0.85 0.76 0.78 0.80Table 5
Fig. 5. Diameter (mm) and density (g/cm3) values of ring and OE-rotor yarns
Fig. 6. Shape and roughness (CV FS %) values of ring and OE-rotor yarns

0.3 mm and 8 mm cut length taken into account. On
the other hand, shape is a factor which indicates theaverage yarn roundness of the yarn. Roughnessvalue corresponds to the ratio of the short-to the longmain axis of an ellipse (1 = circular, 0.5 = ellipse ½ aswide as long) [17]. If a general evaluation is made forshape and roughness values of yarns, it is seen thatyarn roughness (CV FS%) decreases while theshape (roundness) factor increases for both spinning
systems. It is seen that acrylic yarns have highershape and lower roughness values for ring and OE-rotor spinning systems.
Yarn hairiness
Yarn hairiness values (S1+2, S3 and H) of ring and
open-end spun cotton, modal and acrylic yarns areshown in figure 8.
ANOVA results are given in table 8.
When a general evaluation is made in terms of spin-ning technologies and raw material, it is seen that theeffect of spinning system and the effect of raw mate-rial are statistically significant on yarn hairiness,whether the hairiness is measured by different princi-ples such as UZHT5 (S1+2, S3) or UT5 (H) (p ≤ 0.05).OE-rotor yarns have lower hairiness values than ringyarns for all types of materials [9, 10]. It is seen thatthe hairiness values of cotton yarns are the highestand acrylic yarns are the lowest for ring yarns. On theother hand, hairiness values of acrylic yarns are thehighest and cotton yarns are the lowest for OE-rotoryarns. The main factor for this situation is the fibreproperties acting differently for each spinning tech-nology. Fibre fineness, fibre length and fibre lengthuniformity are the main factors for hairiness of ringyarns [27]. Higher linear density, shorter length andlower length uniformity values of fibres cause higherhairiness. Cotton fibres used in the study have high-er linear density, shorter fibre length and lower lengthuniformity than Modal and acrylic fibres, which causehigher hairiness values of cotton ring yarns. In addi-tion, because the wrapper fibres mainly cause thehairiness in OE-rotor yarns, acrylic yarns, which havehigher bending stiffness, have the highest hairiness[28–29]. Higher hairiness values of acrylic yarns maybe due to the electrostatic forces occurs by the fibre-to-metal and fibre-to-fibre frictions in production.Acrylic fibres have the highest tendency to be loadedby static electric [30]. Moreover, parts of OE-rotor
86 industria textila 2016, vol. 67, nr. 2 ˘ANOVA RESULTS FOR 2DØ (mm) AND D (g/cm3)
Parameters Spinning System Sum of Squares Mean Square F Sig.
2DØ (mm)RING 0.002 0.001 206.430 0.000
OE-ROTOR 0.002 0.001 260.071 0.000
D (g/cm3)RING 0.040 0.020 230.192 0.000
OE-ROTOR 0.024 0.012 182.672 0.000Table 6
ANOVA RESULTS FOR SHAPE AND ROUGHNESS (CV FS%)
Parameters Spinning System Sum of Squares Mean Square F Sig.
ShapeRING 0.002 0.001 29.400 0.000
OE-ROTOR 0.005 0.002 28.562 0.000
Roughness
(CV FS %)RING 7.952 3.976 34.963 0.000
OE-ROTOR 12.773 6.386 236.281 0.000Table 7
Fig. 7. Cross-sectional images of ring and OE-rotor
yarns: a– cotton-ring; b – cotton-rotor; c – Modal-ring;
d– Modal-rotor; e – Acrylic-ring; f– Acrylic rotora b
c d
e f

machine such as opening roller, rotor groove, navel
etc. make fibres to rub either the metal surfaces oreach other excessively.
Yarn friction
The mean values of yarn friction coefficients for cot-
ton, Modal and acrylic yarns spun in ring and open-end systems are given in t
able 9 and figure 9. Results
of variance analysis of these values are shown intable 10. A general assessment of spinning systems showsthat the effect of spinning technologies is statisticallysignificant on frictional properties of yarns (p ≤ 0.05).
Friction coefficients of ring yarns are higher thanOE-rotor yarns for yarn-to-metal, yarn-to-ceramicand yarn-to-yarn friction and for all of the raw materi-als. The possible reason for this situation could bethe increasing surface area. The fibres are located ina helical path in ring spun yarns. In OE-rotor yarns,fibres are located randomly and hold together by theaid of wrapper fibres. When a contact occursbetween friction surface and yarns, in ring yarns allthe surface fibres contact with friction surface andthey will be subjected to the frictional forces, whereas
87 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 8. Yarn hairiness values of ring and OE-rotor yarns
Fig. 9. YM, YC and YY friction coefficient values of ring and OE-rotor yarnsANOVA RESULTS FOR YARN HAIRINESS
Parameters Spinning System Sum of Squares Mean Square F Sig.
S1+2RING 153508494.4 76754247.2 47.698 0.000
OE-ROTOR 118119434.1 59059717.04 119.918 0.000
S3RING 772605.068 386302.534 11.809 0.001
OE-ROTOR 7762760.083 3881380.042 55.487 0.000
HRING 0.398 0.199 3.633 0.052
OE-ROTOR 4.839 2.419 345.077 0.000Table 8

in OE-rotor yarns only the wrapper fibres. This situa-
tion will cause increasing asperities, real contact areaand friction force for ring spun yarns. In addition,higher hairiness values of ring yarns should be takeninto consideration as another factor increasing realcontact area and frictional forces.Upon a general evaluation of the friction measure-ment methods, it is seen that coefficient of yarn-to-yarn friction measured by twisted strand method, dif-ferences between the friction coefficients of ring andOE-rotor yarns are quite smaller than other surfaces.The main factor for this situation is thought to be thedifferences between measurements of yarn friction.Difference between the yarn-to-yarn friction coeffi-cients of ring and OE-rotor yarns are higher forCapstan method such as yarn-to-metal and yarn-to-ceramic friction.It is seen that the friction coefficients of Modal andacrylic yarns for both spinning systems and all frictionsurfaces are very close to each other and generallythe differences between the friction coefficients ofModal and acrylic yarns are not statistically signifi-cant (p > 0.05). Despite the fact that fibre-to-surfacefriction of acrylic is high, relatively lower values ofyarn-to-yarn and yarn-to-material frictions of acrylicyarns are remarkable. It can be due to the lowerroughness and higher shape factor of acrylic yarns.Although it is known that fibre friction is one of themost important parameter that effects yarn friction, itis also known that yarn friction is a complex phe-nomenon and unevenness and structural propertiesof yarns highly affect the friction. CONCLUSION
The effects of raw material and spinning technology
on physical properties of yarns were investigated inthe scope of this study . Natural (100% cotton), regen-
erated (100% Modal) and synthetic (100% acrylic)fibres were chosen as raw materials.
Yarns were pro-
duced systematically in both ring and OE-rotor spin-ning systems. Physical properties of yarns such asunevenness, imperfections, diameter, density, rough-ness, shape, hairiness and friction (yarn-to-metal,yarn-to-ceramic and yarn-to-yarn) were evaluated tocompare the effects of spinning system and rawmaterial. The results indicated that raw material andspinning system take important role on physical prop-erties of yarns. The effect of the spinning system was found statisti-cally significant on unevenness and imperfectionsvalues. Unevenness and imperfection values of OE-rotor yarns were found higher than ring yarns for allraw material types. Moreover, the results show thatOE-rotor yarns have higher diameter and roughness;on the other hand, they have lower density, shapefactor, hairiness and friction values for cotton, Modaland acrylic yarns. OE-rotor yarns have lower hairi-ness values than ring yarns for all types of materials.Therefore, it is possible to say that OE-rotor yarnsare more bulky. Permeability properties of fabricsproduced from OE-rotor yarns are better due to thehigh volume and low hairiness of these yarns.Friction coefficients of ring yarns are higher than OE-rotor yarns for yarn-to-metal, yarn-to-ceramic andyarn-to-yarn friction for cotton, Modal and acrylic
88 industria textila 2016, vol. 67, nr. 2 ˘FRICTION COEFFICIENT VALUES OF RING AND OE-ROTOR SPUN YARNS
Friction CoefficientRING OE-ROTOR
Cotton Modal Acrylic Cotton Modal Acrylic
Yarn-to-metal 0.284 0.272 0.270 0.219 0.137 0.136
Yarn-to-ceramic 0.294 0.287 0.286 0.240 0.167 0.165
Yarn-to-yarn (Capstan) 0.293 0.250 0.242 0.256 0.195 0.189
Yarn-to-yarn (Twisted Str.) 0.207 0.182 0.176 0.188 0.173 0.174Table 9
ANOVA RESULTS FOR YARN FRICTION
Parameters Spinning System Sum of Squares Mean Square F Sig.
Yarn-to-metalRING 0.001 0.000 74.494 0.000
OE-ROTOR 0.027 0.013 210.253 0.000
Yarn-to-ceramicRING 0.000 5.579E-0.05 13.913 0.000
OE-ROTOR 0.022 0.011 300.779 0.000
Yarn-to-yarn
(Capstan)RING 0.009 0.004 294.806 0.000
OE-ROTOR 0.017 0.008 156.266 0.000
Yarn-to-yarn(Twisted Str.)RING 0.003 0.002 458.371 0.000
OE-ROTOR 0.001 0.000 72.826 0.000Table 10

yarns. Ring yarns have higher friction coefficient val-
ues than OE-rotor yarns due to the higher real con-tact area. This situation is the similar for the fabricsthat were produced from these yarns.When the effect of raw material was investigated, itwas observed that cotton yarns have higher uneven-ness, imperfections, diameter, roughness, hairinessand friction due to having shorter fibre length andcoarser fibre fineness. Acrylic yarns have the lowestvalues for both ring and OE-rotor spinning systemsby considering the unevenness and optical uneven-ness. Many researchers state that the effect of rawmaterial on yarn properties is important. However,the results showed that unevenness, imperfections,hairiness and friction values of Modal and acrylicyarns which have the same fibre length (38 mm) and
the same fibre fineness (1.3 dtex) are very close toeach other, especially for ring yarns. In this case, itcan be concluded that the effect of fibre fineness andfibre length have higher importance than the effect ofraw material for Modal and acrylic yarns. The findings in this study emphasized the effects ofraw materials and spinning systems on yarn physicalproperties. Therefore, this will contribute to the pref-erence of manufacturers for a specific product orarea of usage.
Acknowledgements
Thanks to TÜBİTAK (2211 National Doctorate Scholarship
Program) and Kip
aș Holding A.Ș. for their contributions to
the study.
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Authors:
GONCA BALCI KILIC1
AYȘE OKUR1
Dokuz Eylül University
1Faculty of Engineering, Department of Textile Engineering
Tinaztepe Campus-35397
Buca-Izmir-TURKEY
e-mail: gonca.balci@deu.edu.tr, ayse.okur@deu.edu.tr
Corresponding author:
GONCA BALCI KILIC
gonca.balci@deu.edu.tr

INTRODUCTION
Yarn properties are defined with raw material compo-
sition and it
s structure. Yarn structure for an approxi-
mately equal twist factor greatly depends on thearrangement of fibers both in the cross section and inthe length direction. For a specific spinning process(carding, half-combing and combing) it is not alwayspossible to obtain a sufficiently uniform structure ofthe yarn. Therefore, spun yarns have a certainunevenness (total unevenness, thick and thin placesand neps), resulting in a different distribution of thesize pick-up in the yarn. It is therefore of great impor-tance to know yarn structure and propertied well inorder to optimize size pick-up in the sizing process[1–4]. The single yarn used in the warp should be sized toenhance strength, smoothness and abrasion resis-tance and to reduce static electricity, reducing the fre-quency of weak places. In the weaving process warpthreads are exposed to higher dynamic forces whichcan cause breaks reducing the efficiency of weavingmachines and fabric quality. To achieve high qualitysizing, it is necessary to keep the equal quality of sizepick-up constant from the beginning to the end of siz-ing, which is often a complicated task. By applying agreater amount of size the sizing process becomesuneconomical. Substance balance is used to defineseveral influential parameters of the sizing process.According to the previous investigations of substancebalance three parameters that can be monitored andcorrected continuously are important, and they directlyaffect size pick-up. These are: inlet and outlet warp
moisture and size concentration [5–8]. In order to reduce sizing costs, to achieve greaterenvironmental protection and to obtain optimum qual-ity of the sized warp, the sizing with warp prewettingwas investigated. It is known that in sizing withoutprewetting the size pick-up becomes thicker for tworeasons: the yarn absorbs water more easily than thesize and one part of the water from the size evapo-rates. By immersing the warp with prewetting into thesize one part of the water is released and the size isdiluted which affects the parameters of the sizedwarp. When sizing the wet warp the size remainslonger on the surface creating a surface film aroundthe yarn which protects the yarn sufficiently againstdynamic forces and abrasion in the weaving process[9–12]. Thick places have an opener structure and a lowertwist level than thin places so that the size penetratesthem more easily. Depending on own friction proper-ties and abrasion resistance as well as on surfacecharacteristics of friction elements, the yarn wearsmore or less, deforms and changes the surfacewhich can result in breaks. In case of testing abrasionresistance, as a measure of resistance the number ofyarn passages over the abrading element is used sothat the sizing effect can be evaluated by measuringabrasion resistance [13, 14]. The goal of sizing is toprotect the yarn in the weaving process againstdestruction, especially in weak places, which isachieved by sticking the fibers to the yarn body.
91 industria textila 2016, vol. 67, nr. 2 ˘Diversity of spun yarn properties sized with andwithout prewetting
STANA KOVAČEVIĆ IVANA GUDLIN SCHWARZ ZENUN SKENDERI
REZUMAT – ABSTRACT
Diversitatea proprietăților firelor încleiate cu și fără înmuiere prealabilă
Obiectivul lucrării a fost de a investiga proprietățile mecanice ale firelor cu finețe diferită și cu coeficienți similari de
torsiune din fibre T
encel, încleiate cu și fără înmuiere prealabilă, folosind concentrații diferite de încleiere. S-a constata t
că firul încleiat cu înmuiere prealabilă are întotdeauna un grad de stoarcere mai mic decât firul încleiat fără înmuiereprealabilă și proprietăți relevante mai bune (rezistență mai mare la abraziune și frecvență mai mică a pilozității). Acestlucru este de o importanță deosebită, datorită avantajelor exprimate în termeni ecologici și economici, deoarece aceleașiproprietăți sau proprietăți mai bune sunt obținute cu un grad de stoarcere mai mic.
Cuvinte-cheie: încleiere, înmuiere prealabilă, stoarcere, proprietățile firului
Diversity of spun yarn properties sized with and without prewetting
The goal of the paper was to investigate mechanical properties of yarns with various fineness and with similar twist
factors made of Tencel fibers, sized with and without prewetting sizing process, using different size concentrations. Itwas found that the yarn sized with prewetting has always a lower size pick-up than the yarn sized without prewetting,as well as better relevant properties ( greater abrasion resistance and lower frequency of protruding fibers). This is of
p
aramount importance because of the advantages in ecological and economical terms, since the same or better
properties are achieved with a lower size pick-up.
Keywords: sizing, prewetting, size pick-up, yarn properties

92 industria textila 2016, vol. 67, nr. 2 ˘EXPERIMENTAL
Yarns of counts 14, 16, 20, 28 and 35 tex spun from
100%
Tencel fibers were used for the purposes of
this research. The following parameters were tested:
•size pick-up
•breaking properties on the Statimat M (Textechno)
strength tester according to standard ISO 2062;
•yarn twist was tested on the MesdanLab Twisttester according to standard 17202;
•abrasion resistance was tested on a ZweigleG-551 abrasion tester; simultaneously 20 threads
were tested under a load of 20 g; the yarn wasabraded by moving the roller back and forth whichis coated with sand paper with a fineness of 800over the thread surface over 7 cm until threadbreakage;
•hairiness before and after sizing was tested on a
Zweigle G 565. The instrument measures the total
number of protruding fibers at specified distances,in our case of n
1 = 2 mm; n2 = 4 mm, n3 = 6 mm and
n4 = 8 mm from the yarn edge. The yarn speed
was 50 m/min and the length of yarn tested was25 m.
An increase in yarn strength caused by sizing wasdetermined according to the equation (1):
σ(sized yarn ) – σ (unsized yarn )I=
×100 (%) (1)
σ(unsized yarn )
where: I(%) is strength increase by sizing; σ (cN/tex)
– tensile strength.Sizing was performed on a specially designed sizingmachine (figure 1) without and with water prewetting. The laboratory sizing machine consists of a creel forcross-wound bobbins with possible yarn tension con-trol, a box for prewetting warp before sizing, a sizebox, a contact dryer and a winder of the sized yarn(figure 1). The prewetting box consists of an immer-sion roller and a pair of squeezing rollers with possi-ble water heating up to 100 °Cand control of squeez-
ing water from the warp. The size box consists of apre-box and a working box with two pairs of immer-sion rollers and two pairs of rollers for size squeez-ing. The role of the pre-box is to keep size levels inthe working box constant, namely continuous sizecirculation from the working box to the pre-box withnatural flow, and from the pre-box to the working box
using a pump. During the sizing process it is possibleto keep water temperature constant in the pre-wettingbox and size temperature in the size box with inte-grated heaters and thermostats, which indirectlywarm up the water and size through the walls of theboxes. Drying the sized yarn is performed by contact,by passing across the two heated cylinders of thecontact dryer. Sizing speed can be kept constantusing the winder and an additional speed controller. Concentrations, recipes and technological sizingconditions were as follows:
•concentration 5%, recipe: 1 l of water + 50 g
Tuboflex PVA80 + 4 g Tubowax 24,
•concentration 10%, recipe: 1 l of water + 100 gTuboflex PVA80 + 8 g Tubowax 24,
•concentration 15%, recipe: 1 l of water + 150 gTuboflex PVA80 + 12 g Tubowax 24,
•size temperature 75 –80 °C; sizing speed 2 m/min;
temperature of contact cylinder drying 135 °C,
•pressure on the back part of the pair of the rollers
at the exit of the working box 0.66 N/cm2,
•warp moisture before sizing 6.5%; warp moistureafter the exit of the prewetting box 72%; warpmoisture after the exit of the size box 80%; warpmoisture after drying 5%.
The applied sizing agents were made by Bezema
Company. Yarn tension was measured with a tensionmeter Schmidt Model ETM which had been recon-structed with the aim of measure and to save datacontinuously. A computer was used to record themeasurements of output yarn moisture after dryingand yarn tension after the creel. A Zeiss Jena hand-held refractometer was used to measure size con-centration. When sizing yarn without prewetting on the laborato-ry sizing machine, the prewetting box with hot waterwith a temperature 50 to 60 °C (mark 5 in figure 1) isremoved.The size pick-up in relation to the sized yarn wasdetermined according to equation (2):
m
s – muS= ×100 (%) (2)ms
where: S(%) is the size pick-up, ms(g) – mass of the
dry sized yarn, mu(g) – mass of the dry unsized yarn.
Twist factor atexwas determined according to
equation (3):
αtex= Tx √Tt (3)
where: T(twist/m) is the number of twists, Tt(tex) –
yarn count.
RESULTS AND DISCUSSION
Y
arn twist
The number of twists changed with changing yarn
count
s so that the finest yarn 14 tex had the highest
number of twists (871 twist/m), while the coarsestyarn 35 tex had the lowest number of twists (581twist/m) (table 1). Yarn twist factor was 3140.0 for theyarn of 16 tex to 3437.2 for the yarn of 35 tex.
Fig. 1. Laboratory sizing machine: 1 – creel for cross
wound bobbins, 2 – thread guide and brake, 3 – comb,
4 – tension meter, 5 – pre-wetting box with hot water,
6 – size box, 7 – dryer, 8 – humidity measuring instru-
ment, 9 – winder of the sized yarn, 10 – computer

93 industria textila 2016, vol. 67, nr. 2 ˘Size pick-up
The size pick-up increased with increasing yarn count
and size concentration (C) in both sizing processesfor all tested yarns (t
able 2, figure 2). Thus, the finest
yarn (14 tex) sized with and without prewetting hadthe lowest size pick-up for all concentrations. Theseresults suggest that despite similar twist factor, afterbeing subjected to sizing process under the sameconditions, finer yarns maintain a smaller percentageof size, i.e. size penetration into the spaces betweenfibers is much harder as well as retaintion of size onthe surface of the yarn with a smaller diameter. Sizepick-up of yarns sized with prewetting in relation to
yarns sized without prewetting are significantly lower.
That difference is particularly pronounced at smallsize concentration (5%) for all yarns and also at fineryarns (14 tex, 16 tex) sized with all size concentration(in average for almost 20%). All the above confirmsthat the sizing with prewetting is more economical.Parameters of breaking properties of all testedunsized and sized yarns are shown in tables 3–5.YARN TWIST PARAMETERS
ParametersTt(tex)
14 16 20 28 35
T (twist/m) 871 785 755 639 581
CV(T) (%) 2.8 3.3 2.7 3.6 6.6
atex– twist factor 3258.9 3140.0 3376.5 3381.3 3437.2Table 1
Table 2
Table 3SIZE PICK-UP WITHOUT AND WITH PREWETTING
Size pick-up C (%)Tt(tex)
14 16 20 28 35
Swo(%) – without
prewetting5 6.58 6.83 6.75 7.09 9.41
10 7.91 8.28 8.31 9.94 12.84
15 12.17 12.33 12.90 15.00 18.01
Sw(%) – with
prewetting5 5.21 5.32 5.44 7.03 8.22
10 6.11 7.41 8.17 9.83 12.40
15 10.09 11.99 12.47 14.77 17.05
PARAMETERS OF THE UNSIZED YARN
ParametersTt(tex)
14 16 20 28 35
F (cN) – breaking force 253.5 301.4 455.6 691.5 859.7
CV(F) (%) 12.5 10.1 7.2 6.2 5.0
ε(%) – elongation at break 6.1 6.4 6.9 8.1 8.3
CV(ε) (%) 9.2 9.0 8.2 5.9 5.6
W (cNxcm) – work to rupture 472.6 594.4 974.6 1647.6 2120.8
CV(W) (%) 20.0 17.9 13.9 11.6 10.0
σ(cN/tex) – tensile strength 18.1 18.8 22.8 24.7 24.6
Fig. 2. Dependence of size pick-up and breaking force
of the yarn on concentration and yarn count:
Fswo(%) – breaking force of the yarn sized without
prewetting, Fsw(cN) – breaking force of the yarn sized
with prewetting, Fu(cN) – breaking force of the unsized
yarn; C5, C10, C15 – size concentration of 5%, 10%
and 15%

Tensile strength
By reducing yarn count (increasing fiber number in
the cross section) in an narrower range of twist factor(3140.0 to 3437.2) the strength of the unsized yarnincreases for 27% (from 18.1 cN/tex to 24.7 cN/tex)(t
able 3). By sizing yarn strength and breaking force
increases as expected (tables 4 and 5). By reducingthe yarn count from 14 tex to 20 tex an increase instrength for all size concentrations of the sized yarnwithout prewetting was observable, by an average of3.1 %. By further reducing the yarn count from 20 texto 35 tex the strength of the sized yarn is reduced, byan average of 1.7%. According to the obtained resultsof tensile strength between yarns sized with two pro-cesses, a great similarity is observable. A strengthreduction in the sized yarn with prewetting does notstart at 20 tex as in the sized yarn without prewetting,but it starts at the yarn count of 28 tex to 35 tex.Therefore, it can be concluded that there are limits ofyarn fineness over which the strength of sized yarnsno longer increases and these are 20 tex yarn in siz-ing without prewetting and 28 tex yarn in sizing withprewetting. Strength increase of the yarn sized with both sizingprocess in relation to the unsized yarn indicates thatin case of rougher yarns (28 tex and 35 tex) strength
values amounts from 12.7% to 37.4%, while in caseof finer yarns (14 tex and 16 tex) it is much higherand ranges from 40.5% to 72.4%. A lower size pick-up of the yarn sized with prewetting at lower concen-trations reflected in a lower increase in yarn tensilestrength due to sizing, but only at lower concentra-tions (5% and 10%). At higher size concentration(15%) an increase in tensile strength of the yarnsized with prewetting is mainly higher. This indicatesthat an increase in the size concentration increasesstrength of the yarn sized with prewetting.
Elongation at break
Elongation at break of the unsized yarn increases
with reducing yarn count from 14 tex to 35 tex, inaverage for 27% (values range from 6.1 % to 8.3%)and follows the course of breaking forces. Generally
,
the sizing process reduces the elongation at breakfor all tested yarns. The yarns sized without prewet-ting have elongation at break in the range from 3.6%to 5.2%, while in case of sizing with prewetting itranges from 3.1% to 5.8%. Elongation at break of theyarn slightly increases by reducing yarn count at allconcentrations and with both sizing processes. It was
94 industria textila 2016, vol. 67, nr. 2 ˘Table 4
PARAMETERS OF THE YARN SIZED WITHOUT PREWETTING
Parameters C (%)Tt(tex)
14 16 20 28 35
F (cN)5 394.8 446.0 575.9 787.1 969.1
10 396.9 470.1 582.9 806.0 985.1
15 399.5 487.2 608.6 830.7 1024.0
CV(F) (%)5 6.4 6.1 5.7 11.6 7.1
10 8.4 7.6 7.5 8.5 7.4
15 11.5 8.9 5.4 21.9 5.2
ε(%)5 3.6 4.0 4.1 4.3 4.0
10 3.8 4.7 5.2 5.2 5.1
15 4.0 5.0 4.8 5.1 5.2
CV(ɛ) (%)5 8.7 9.9 8.5 16.6 11.8
10 12.0 11.5 15.1 13.2 8.8
15 22.5 17.9 7.6 27.2 8.9
W (cNxcm)5 486.1 758.6 889.7 1411.3 1948.0
10 507.2 746.7 1000.1 1386.8 1969.6
15 528.7 674.4 1041.5 1261.2 1655.2
CV(W) (%)5 14.8 14.9 14.1 24.2 18.4
10 18.4 19.9 17.4 20.5 14.3
15 31.4 25.5 12.5 35.4 14.2
σ(cN/tex)5 28.4 27.9 30.5 28.8 29.3
10 28.5 29.4 29.2 29.7 27.715 28.2 30.5 28.8 28.1 28.2
I (%) – strength
increase by sizing5 56.6 48.0 33.7 16.6 19.1
10 57.7 56.0 28.0 20.1 12.7
15 55.8 61.7 26.4 13.8 14.6

noted that yarn elongation by increasing size con-
centration from 5% to 15% decreases in case of siz-ing with prewetting, while in case of sizing withoutprewetting this occurrence was not observed. By siz-ing the fibers within the yarn structure are fixed to acertain extent, the yarn becomes more compact,stronger and stiffer, resulting in a reduction of elon-gation at break and representing a negative featureof the yarn after sizing.
Work to rupture
Changed structure of the sized yarns changes the
properties of work to rupture, being very import
ant
parameter in the production in terms of defining theweaving conditions. According to the obtainedresults, it is evident that sizing without prewetting ofrougher yarns (28 tex and 35 tex), with all size con-centrations, decreases the values of work to rupture.Also, that kind of work decrease of yarns sized withprewetting in regard to unsized yarns was evident forall yarn counts sized with a 15% size concentration;for yarn counts of 20 tex, 28 tex and 35 tex sizedwith a 10% size concentration; and for a yarn countof 35 tex sized with a 5% size concentration.Regardless of the increase in breaking force ofrougher yarns caused by the increase in the numberof fibers in the cross section and also caused by siz-ing procedure, lower breaking elongation of sizedyarns significantly affected on the reduction of thework of the above listed yarn counts and size con-centrations.
Abrasion resistance
It is known that higher yarn abrasion resistance
reduces the number of warp breakages in the weav-ing process. Rougher unsized yarns have subst
an-
tially higher abrasion resistance than finer yarns.Thus, a yarn of a count of 14 tex has abrasion resis-tance 36.6 cycles to breakage, while the yarn with acount of 35 tex has 197.5 cycles to breakage, whichis 440% more (table 6, figure 3). Sizing processresults in substantially higher yarn abrasion resis-tance, for both sizing process. By reducing yarncount abrasion resistance increases mainly in bothsizing processes and at all three size concentrationlevels. It was observed that in case of rougher yarncounts of 28 tex and 35 tex abrasion resistance is thehighest when applying 10% size concentration inboth sizing processes, regardless of a higher sizepick-up on the yarns sized with a 15% size concen-tration. It points to the fact that abrasion resistanceincreases with the size pick-up only to a certain limit.
95 industria textila 2016, vol. 67, nr. 2 ˘PARAMETERS OF THE YARN SIZED WITH PREWETTING
Parameters C (%)Tt(tex)
14 16 20 28 35
F (cN)5 378.5 423.2 560.3 883.7 1021.5
10 383.6 452.0 605.1 898.8 1016.6
15 390.4 519.5 632.15 900.6 1071.5
CV(F) (%)5 4.8 27.1 8.9 16.4 15.4
10 7.6 17.3 13.0 22.2 3.4
15 13.8 6.6 6.1 6.4 7.1
ε(%)5 4.9 4.9 5.2 5.7 5.8
10 4.6 4.6 4.8 5.3 5.4
15 3.2 3.1 3.7 3.8 4.3
CV(ɛ) (%)5 9.5 23.3 13.5 5.1 26.0
10 6.7 24.8 24.7 16.3 5.9
15 18.6 12.6 18.0 12.7 18.2
W (cNxcm)5 610.2 558.8 1035.4 1702.6 1942.7
10 575.6 713.7 885.7 1465.2 2048.8
15 414.9 510.5 744.1 1079.6 1643.4
CV(W) (%)5 13.0 40.1 21.5 43.8 29.9
10 13.0 32.7 30.6 26.2 8.5
15 29.1 19.0 22.6 18.9 21.9
σ(cN/tex)5 27.4 26.5 30.3 34.0 29.2
10 27.0 28.3 28.0 28.0 29.115 27.9 32.5 31.6 32.1 30.6
I (%) 5 51.4 40.5 32.8 37.4 18.7
10 49.4 50.0 23.0 13.3 18.3
15 54.1 72.4 38.7 30.0 24.6Table 5

An increase in yarn abrasion resistance by sizing is
mostly higher in a yarns sized with prewetting(k
2>k1). It is more significant in a finer yarn (14 tex
and 16 tex).
Yarn hairiness
Yarn hairiness greatly affects the number of yarn
breakages during the weaving process.
Appearance
of protruding fibers results in grip threads, removal oraccumulation on the contact points between threadsand weaving machine parts and thus to pinning andto breakage. The accumulation of short fibers in hed-dles and the reed has the effect of drawing the accu-mulated fibers into the shed and also into the finalwoven fabric, resulting in thickenings in the fabric.
The aim of sizing is to reduce yarn hairiness andaccording to the obtained results (figure 4, table 7)that is achieved. The frequency of protruding fibers was reduced,especially in the yarn sized with prewetting, whichwas expected because the yarn is smoothed duringprewetting and in this state it enters the size boxwhere the fibers are even more clung to the yarnbody. An exception is 35 tex yarn having a greaternumber of longer protruding fibers after sizing with
96 industria textila 2016, vol. 67, nr. 2 ˘ABRASION RESISTANCE OF THE YARN (AVERAGE NUMBER OF CYCLES TO BREAKAGE)
Tt
(tex)Abrasion
hu– average No.
of abrasion cycles
to breakage –
unsized yarnC (%)hswo– average
No. of abrasion
cycles to
breakage –
without
prewettingk1– quotient of
the increase in
abrasion resistance
of the yarn sized
without prewetting
in relation to the
unsized yarnhsw– average
No. of abrasion
cycles to
breakage –
with prewettingk2 – quotient of
the increase in
abrasion resistance
of the yarn sized
with prewetting in
relation to the
unsized yarn
14 36.65 193 4.3 384 9.5
10 292 7.0 416 10.4
15 237 5.5 577 14.8
16 46.55 335 6.2 354 6.6
10 392 7.5 496 9.7
15 531 10.4 516 10.1
20 92.25 261 1.8 428 3.6
10 460 4.0 730 6.9
15 473 4.1 486 4.3
28 160.95 407 1.5 617 2.8
10 779 3.8 1155 6.2
15 594 2.7 676 3.2
35 197.55 676 2.4 846 3.3
10 1085 4.6 1777 7.9
15 910 3.6 1698 7.6Table 6
Fig. 3. Abrasion resistance of the unsized
and sized yarns
Fig. 4. Yarn hairiness of the yarn after sizing over the
lengths of 2 mm (n1) and 4 mm (n2) (table 7):
n1swo, n2swo– number of protruding fibers on the sized
yarn without prewetting, n1sw, n2sw– number of
protruding fibers on the sized yarn with prewetting

5 % size concentration and with prewetting process
then the yarn sized without prewetting. This occur-rence can be related to the assumption that a lowersize concentration achieves a lower efficiency ofclinging shorter fibers to a wet and rougher yarn.The shortest length of protruding fibers (2 mm) is themost numerous before and after sizing, but thatlength of protruding fibers does not affect quality fea-tures of the yarn. The longer the protruding fibers, thegreater is the possibility to cause a more frequentstandstill of the weaving machine and lower qualityfabric.
CONCLUSIONS
By sizing the warp threads are protected from
destruction which might occur during the weavingprocess.
That is particularly important in order to pro-
tect the weak spots that are actually potential pointsof breakage. Yarn unevenness affects the frequencyof thick and thin places and despite the similar twistfactors it varies from parts of the yarn. Thick placeshave fewer twist and size more easily penetrate intothe interior of the yarn over the thin places. Findingthe amount of size pick-up that will be optimal,requires long and complex analysis of the sizing andweaving processes. By the obtained results it can beconcluded that the size pick-up changes as well asphysical-mechanical properties of the yarn by differ-ent counts and sizing processes (with and withoutprewetting) despite similar twist factors of the yarns.The reason for different amounts of size pick-up is inthe distribution and binding of size in the yarn.Prewetting allows filling the interspaces of the yarnwith water. During the immersion of such wet yarn insize leads to diffusion of water (retained in the yarn)with size and very rapid mutual bonding, allowingquicker and easier penetration of size into the yarn.
However, the concentration of size inside the yarn islower, because the retained water dilutes it.Therefore the amount of size pick-up is lower (thanon the yarn sized without prewetting process), butstill sufficient to protect the yarn from the dynamicforces and tears in the weaving process. Loweramount of size pick-up on the yarn also means a sig-nificant economic and ecologic advantage.The following conclusions can be obtained after siz-ing yarns with similar twist factors, under the samesizing conditions:
•Yarn size pick-up rises by increasing size concen-tration and by reducing yarn fineness.
•Size pick-up on the yarns sized with prewettingprocess is mainly lower in relation to yarns sizedwithout prewetting.
•By analyzing the obtained results, it can be con-cluded that there are limiting finenesses towardsthe rougher yarns whose tensile strength does notincrease after sizing.
•An increase in tensile strength by sizing yarnsoccurs, especially in finer yarns up to 72 % whilein rougher yarns only up to 37 %. Lower size pick-up on the yarn sized with prewetting at lower sizeconcentrations reflected also in a lower increase inbreaking force, while at higher concentrations theincrease is mainly greater. This means thatincreasing the size concentration increases thetensile strength of the yarn sized with prewetting.
•By sizing, elongation at break decreases for alltested yarn counts and sizing conditions. Byincreasing the size concentration from 5 % to15 %, elongation at break decreases for all yarnssized with prewetting, while this occurrence is notobservable for the yarns sized without prewetting.
97 industria textila 2016, vol. 67, nr. 2 ˘YARN HAIRINESS
Tt
(tex)Unsized yarn C
(%)Sized yarn without prewetting Sized yarn with prewetting
n1un2un3un4un1swon2swon3swon4swon1swn2swn3swn4sw
14 1307.6 323.6 38.6 5.45 198 13 4 3 201 21 2 2
10 116 16 1 1 107 16 1 2
15 262 20 2 3 114 3 3 7
16 1023.0 203.4 19.0 1.65 481 40 7 5 174 23 1 1
10 176 21 0 5 73 6 1 115 356 46 9 17 105 22 2 8
20 1254.8 258.8 28.2 6.25 132 17 6 3 164 21 0 1
10 129 12 2 0 57 12 1 315 281 38 1 21 106 7 3 5
28 1347.8 266.0 26.4 3.65 272 32 6 1 213 12 2 2
10 126 16 3 6 42 5 2 215 210 28 14 5 99 4 11 9
35 1547.4 331.2 47.0 3.45 118 11 1 0 165 24 1 6
10 137 5 0 0 34 7 3 215 368 30 7 6 42 0 2 5Table 7

•Regardless of increase in breaking force due to
sizing, a reduction of elongation at break substan-tially affected the reduction of work to rupture,especially in case of rougher yarns.
•Yarn abrasion resistance increases by sizing.Rougher yarns sized with a 10 % size concentra-tion have the highest yarn abrasion resistance forboth sizing processes, regardless of the fact thatsize pick-up is higher when sizing with 15% sizeconcentration. An increase of yarn abrasion resis-tance due to sizing is usually greater for the yarnsized with prewetting and it is more distinct for fineryarns.
•The frequency of protruding fibers is reduced bysizing, especially for the yarns sized with prewet-ting. The reason for this is that already duringprewetting in water the threads are smoothed and
by immersing in the size and squeezing an exces-sive size amount the protruding fibres cling to thethread even more.
The yarns sized with prewetting process have advan-tages in ecological and economical terms since thesame or better properties are achieved with a lowersize pick-up. Likewise, under the same sizing condi-tions the yarn sized with prewetting has greater yarnabrasion resistance and lower frequency of protrud-ing fibers. By exceeding certain limiting values of sizeconcentration and yarn count, tensile strength andelongation at break of sized yarn start changing non-linearly.
98 industria textila 2016, vol. 67, nr. 2 ˘Authors:
Chief of works Prof. dr. ST ANA KOVAČEVIĆ
Dr. IVANA GUDLIN SCHWARZ
Prof. dr. ZENUN SKENDERI
University of Zagreb
Faculty of Textile Technology, Department of Textile Design and Management
Prilaz baruna Filipovica 28a, 10000 Zagreb, Croatia
e-mail: stana.kovacevic@ttf.hr, ivana.schwarz@ttf.hr, zenzn.skenderi@ttf.hrBIBLIOGRAPHY
[1] Kovačević, S. Determining Size Coat in Yarn on the Basis of Substance Content , Ph.D. thesis, Faculty of Textile
Technology, University of Zagreb, 2000.
[2] Gudlin Schwarz, I. Technological Justification and Optimization of Pre-Wet Sizing , Ph.D. thesis, Faculty of Textile
Technology, University of Zagreb, 2012.
[3] Perković, V. Impact of Yarn count of the Same Twist Coefficient on Size Pick-up , Bs.C. thesis, Faculty of Textile
Technology, University of Zagreb, 2010.
[4] Kovačević, S. et al. Optimising Size Layer As Related to Input Humidity , In: Tekstil, 49 (2000) 12, pp. 689–697.
[5] Behera, B.K.; Hari, P.K. Woven textile structure, Published by Woodhead Publishing Limited in association with The
Textile Institute Woodhead Publishing Limited, Campridge, UK, 2010. www.woodheadpublishing.com
[6] Kovačević, S.; Grancarić, A. M., Stipančić, M. Determination of the Size Coat , In: Fibres & textiles in Eastern
Europe , 10 (2002) 3, pp. 63–67.
[7] Kovačević, S.; Dimitrovski, K.; Orešković, V. Optimization of Size Pick-up on Yarn , 2nd International Textile, Clothing
& Design Conference, Magic World of Textiles , October 03rdto 06th2004, Dubrovnik, Croatia.
[8] Gudlin Schwarz, I.; Kovacevic, S.; Dimitrovski, K.: Comparative Analysis of the Standard Sizing Process and the
Pre-wet Sizing Process , In: Fibres & Textiles in Eastern Europe, 19 (2011) 4 (87), pp. 135–141.
[9] Gudlin Schwarz, I.; Kovačević, S.; Dimitrovski, K.: Analysis Of Changes In Mechanical And Deformation Yarn
Properties by Sizing , In: Textile Research Journal ,81 (2011) 5, pp. 545–555.
[10] Kovačević, S.; Dimitrovski, K.; Hađina, J. The processes of weaving, University handbook , Faculty of Textile
Technology, University of Zagreb, Zagreb, 2008.
[11]Kovačević, S.: Priprema pređe , Faculty of Textile Technology, University of Zagreb, Zagreb 2002.
[12] Kovačević, S.; Gordoš, D.: Impact of the Level of Yarn Twist on Sized Yarn Properties , In: Fibres & Textiles in
Eastern Europe, 17 (2009) 6, pp. 44–49.
[13] Hađina, J.; Kovačević, S. Influence of Yarn Twist on the Texture of Fabric, In: Tekstil, 47 (1998) 9, pp. 447–452.
[14] Reumann, R.D.: Prüfen von Textilien , VEB Fachbuchverlag Leipzig, 1984.

INTRODUCTION
In recent years, influence of various factors and pre-
diction of transport of water through textiles andmoisture transmission behaviour of the clothing hasbeen recognized as a favorite research. In fact, liquidsorption behavior of fabrics plays an import
ant role in
maintaining thermo-physiological clothing comfort,especially in sweating conditions, in dyeing and fin-ishing of fabrics, in liquid filtration, and so forth [1, 2].In addition, textiles processing can require severaldozen gallons of water for each pound of clothing,especially during the dyeing process. All additionalproducts for dyeing are applied to fib mainly wateras vehicle. Most fabric preparation steps, includingdesizing, scouring, bleaching and mercerizing,require the use of water. Thus, it is necessary to opti-mize its consumption and control its sorption kineticsin textile materials. Also, business competitionbetween industrial leaders is based on minimizingconsumption of natural resources, notably water.To study the liquid-textile contact and to model thisproblem, optimization of various processes involvingliquid-fibre contact, penetration of liquids into capil-laries and textiles, and kinetic sorption of water ontotextile fabric have been studied for many years [ 3–9;10–13]. Among the extensive research in the field of
liquid transport and capillary rise, the fluid flowthrough porous media is modelled by the well-knownLucas and Washburn equation which allows deter-mining the diffusion coefficient [4, 5, 14, 15].Among the extensive researches in the field of liquidtransport, capillary flow through textile materials andliquid adsorption into textile fabrics, many techniqueswere used and developed to study experimentallythis phenomenon. Many researchers developed anelectrical method based on resistivity measurements[6, 7]. Others used a method based on the analysisof CCD images of a coloured liquid [14].The kinetics of the capillary rise in textiles is investi-gated, for short time spans when the effects of gravi-ty are neglected and the extent of the liquid flow inthe fabric is significantly less than the maximum equi-librium height, by fitting the experimental data to thewell-known Washburn equation. For long time, it hasbeen shown that equations derived from Washburnlaw lead to erroneous results. One other approachproposed by Hamdaoui and al., in order to interpret
the sorption kinetics of the vertical capillary rise of
water in woven fabrics. This approach, which has adouble exponential form, is valid for short and longEffect of knitted parameters on wicking behaviours
NESMA SAOUSSEN ACHOUR MOHAMED HAMDAOUI
AYDA BAFFOUN SASSI BEN NASRALLAH
REZUMAT – ABSTRACT
Efectul parametrilor de tricotare asupra capacității de absorbție a apei
În acest articol au fost propuse modele teoretice pentru a estima cap
acitatea de absorbție verticală a apei în funcție de
compoziția, tipul de fire și parametrii țesăturii. Se utilizează un dispozitiv experimental care efectuează suspendarea
verticală a suprafeței țesătură-lichid și care permite pătrunderea moleculelor de apă prin mostrele testate. Valorileexperimentale ale absorbției verticale au fost măsurate gravimetric cu ajutorul unei microbalanțe electronice și studiateteoretic, folosind un model dublu exponențial (DEM). Rezultatele au arătat că DEM se potrivește bine datelorexperimentale cu valori medii semnificative ale coeficientului de determinare. O simplificare a modelului DEM esteefectuată pentru a dezvolta un model liniar care descrie ascensiunea capilară în structurile tricotate. De asemenea, estedemonstrat faptul că cinetica de absorbție este influențată de caracteristicile tricoturilor, cum ar fi compoziția, structuratricotului, tipul de fir și înălțimea ochiurilor.
Cuvinte-cheie: model dublu exponențial, ascensiune capilară, tricoturi, modelare lineară, cinetica de absorbție a apei
Effect of knitted parameters on wicking behaviours
Theoretical models have been proposed in this article to predict the vertical wicking behaviour of fabrics depending upon
composition, yarns and fabric parameters. An experimental device performing the vertical suspension of fabric-liquidsurface and permitting the penetration of water molecules through these tested samples is used. Experimental valuesof vertical wicking were gravimetrically measured using an electronic microbalance and theoretically studied using thedouble-exponential model (DEM). The results showed that the DEM fit well the experimental data with significantaverage determination coefficient values. A simplification of the DEM model is carried out to develop a linear onedescribing the capillary rise into knitted structures. It is also demonstrated that wicking kinetics is influenced by knittedfabric features, such as composition, knit structure, type of yarn and of couliering depth value.
Keywords: double-exponential model, capillary rise, knitted fabrics, linear modelling, water sorption kinetics
99 industria textila 2016, vol. 67, nr. 2 ˘

time. It is found that the parallel double exponential
kinetics model (DEM) fit well the experimental data[10, 11].In this paper, attempts have been made to developand validate mathematical models based on the dou-ble-exponential function for predicting the completeprofile of the water sorption kinetics onto knitted fab-rics and the linear logarithmic function for determin-ing the water kinetic parameter, respectively.
EXPERIMENTAL PART
Materials and Method
The fabric samples used in this study were knitted
using the same machine.
The samples were knitted
by changing fabric structural parameters, such as thekind of yarn, the composition and the knit structure.Table 1 gives the knitting parameters and physicalproperties of each sample used in this study.The dimension of the dry sample used in experi-ments was 20 cm x 30 cm. We used the distilledwater which is used frequently in textile industry. Toremove the natural wax and paraffin oil that has beenapplied to yarns prior to knitting, a chemical treat-ment was used. The fabric was treated for 20 min-utes at 65°C with a solution containing 2 mL/L ofcaustic soda and 2.5 mL/L of wetting agent (LavotanTBU).Figure 1 shows a sketch of the experimental system.It is composed of a device permitting the vertical sus-pension of the fabric-surface on the liquid and a light-ing system. In order to measure the mass of liquidraised, the fabric is attached to a sensitive electronicbalance with the accuracy of 0.001 g. The balancehas the capability of recording the weight of theabsorbed water (g) versus time (s) with its specialsoftware [4–7].
RESULTS AND DISCUSSION
Experiment
al data
The knit fabric is maintained vertically in the warp
direction.
Then, the lab jack is used to hoist the liquid
reservoir containing the distilled water. The mass ofwater absorbed by the textile is automatically deter-mined every 20 seconds. The results of the experi-mental data are reported in figure 2, which shows theevolution of the water mass absorbed by the textileversus the time.Figure 2 also shows that the experimental curve ofthe capillary rise onto the knit fabric has a positiveslope which decreases with time and attains zero atfull saturation. In this case, the uptake process of thedistilled water capillary rise onto knitted fabric could
100 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 1. Experimental device
Fig. 1. Experimental data of water mass absorbed
by the sample 1 and 2 versus time
CHARACTERISTICS OF USED KNITTED FABRICS
Sample CompositionKnit
structureYarn
spinningCouliering
depthThikness
(10–3m)Weight
(g/m2)Porosity
1 100% Cotton Jersey Carded 14 1.99 359.5 0.883
2 80% Cotton – 20% PES Jersey Carded 14 2.13 378.1 0.879
3 100% Cotton Rib 1&1 Carded 14 2.85 419.2 0.869
4 100% Cotton Jersey Open-end 14 2.03 461.1 0.895
5 100% Cotton Jersey Carded 12 2.33 349.0 0.888Table 1

be divided into two phases: the rapid phase and the
slow phase, respectively.
Kinetic sorption study
Mathematical models
In order to interpret sorption kinetic dat
a of water
molecules in cotton fabric, the experimental values ofthe mass of water absorbed by fabric at each timewere curve fitted using MatLab to a double-exponen-tial function [10, 11, 16]. The double exponential formused in this study is given by the following equation:
m
t= me– m1 exp(–K1t) – m2exp(–K2t) (1)
As mentioned above, the uptake process of watersorption on knitted fabrics could be divided into twosteps. The first one is the rapid phase and the secondone is the slow phase.
So, in equation (1): K
1(min–1) and K2(min–1) are the
diffusion parameters of the rapid step and the slowstep, respectively; m
eis the quantity of water absorbed
at equilibrium (saturation of fabric).As shown in figure 3, the DEM curve presented bythe solid line fits well the experimental data with high-er determination coefficient ( R
2= 0.9957). The best
fit model parameters ( me, m1, m2, K1, and K2) corre-
sponding to the higher determination coefficient ( R2)
were given automatically by the MatLab software.Figure 3 displays the water mass absorbed onto thesample 2 curve fitted using MatLab, it can be seenthat the mass of water absorbed at equilibrium ( m
e)
was equal to 14.51 g, the diffusion parameters K1
(s–1) and K2(s–1) were equal to 0.9770 min–1and
0.00170 min–1, respectively. We observe that K1was
very larger than K2, which means that the first and
rapid process can be assumed to be negligible on theoverall vertical capillary kinetics into knitted fabrics[11]. Then, the DEM equation can be simplified to beas:
m
t= me– Cexp(–Kt) (2)
Where, “C” is a constant and “K” is the kinetic param-
eter of the capillary rise of water in knitted fabrics. Equation (2) can be rearranged to linear form:
Ln(m
e–mt) = Ln C – K*t (3)
Kand Ccan be determined by plotting of Ln( me–mt)
against “t”.
Influence of fabric structural parameters
The results of the linear fitting curves of experimental
data of capillary rise in five different knitted fabricsare listed in table 2.Because of its hydrophobic character and so it has aless absorbency ability, the water does not penetrateinto the polyester fibre pore and the capillary kineticof the distilled water in the cotton/polyester knit fabric(sample 2) is higher than in the 100% cotton knit fab-ric (sample 1).We observe also that the value of the capillary diffu-sion parameter “K” in the 100% cotton rib fabric(sample 3) is higher than in the 100% cotton jerseyfabric (sample 1). In fact, the rib fabrics contain morequantities of cotton materials per centimetre than the
jersey fabric.
As the couliering depth value increasers and thestitches number per centimetre are more important,the capillary kinetic coefficient “K” increases. As aconsequence, the quantity of water absorbed by theknit fabric and the capillary rise kinetic parameter arefound to be greater for samples 4 and 5 than for sam-ple 1.On the other hand, the carded yarn is more regularand the cohesion between fibers is greater than theopen-end yarn which is characterized by non regularorganisation of fibres at the section. This explains thedifference of the absorbed water quantity at equilibri-um between sample 1 and 4.Moreover, we note that the linear model equation hasthe same form of the pseudo-first-order equation ofLagergren whose equation is [17]:
k
1Ln (qe–qt) = Ln qe– t (4)2.303
In the study of Yalçin and al., qeand qtare the
amounts of the absorbed dye at an instant ‘t’ and at
the equilibrium and k1is the rate constant of the
pseudo-first-order sorption process. Plots of Ln ( qe–qt)
versus “t” can gives a straight line for pseudo-first-order kinetics, which allows computation of the sorp-tion rate constant k
1, and equilibrium capacity qe.
101 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 3. Water mass absorbed by sample 2 over time
with DEM fitting
INFLUENCE OF FABRIC STRUCTURAL
CHARACTERISTICS ON THE LINEAR MODEL
Sample N° me K (min–1) CR ²
1 18.81 0.0006 16.6182 0.9474
2 14.66 0.0013 12.1667 0.96613 31.04 0.0008 36.8332 0.93384 19.88 0.0288 25.3937 0.92325 20.75 0.0292 28.1009 0.9579Table 2

CONCLUSION
From the present work, mathematical models were
est
ablished and have been demonstrated to be satis-
factory describing the kinetic of water sorptionthrough various knitted fabrics. In fact, the experi-mental data have been interpreted using double-exponential model (DEM) and the simulation curvesshowed good fits with the experimental data. Then,the DEM was simplified to be linear to make easy the
determination of the kinetic coefficient of the capillaryrise of the distilled water in knitted fabric.Along this study, we conclude that the kinetic of watersorption is influenced by a large number of parame-ters like the construction parameters (the knit struc-ture and the couliering depth values) and the compo-sition of fabrics materials (100% natural fiber or ablend of natural and synthetic fiber).
102 industria textila 2016, vol. 67, nr. 2 ˘BIBLIOGRAPHY
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J. Colloid and interface sci., 1977, vol. 60, Issue 3, pp. 497–506
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Indian J Fibre Text Res, 2015, vol. 40, Issue 2
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1988, vol. 58, Issue 10, pp. 581–592
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Authors:
Nesma Sawssen ACHOUR1,2
Ayda BAFFOUN1,2
Mohamed HAMDAOUI1,2
Sassi Ben NASRALLAH1
Monastir University
1National School of Engineers, Department of Textile Engineering
2Laboratoire d’Etudes des Systèmes Thermiques et Energétiques (LESTE Laboratory)
Avenue Ibn Eljazzar-5019
Monastir-TUNISIA
Corresponding author:
M. HAMDAOUI
hamdaouimohamed@yahoo.fr

INTRODUCTION
Knitted rib is a thick fabric made up of coarse yarns.
It
s weight ranges from 200 to 400 grams for every
square meter. In most of the cases, it is used to makeundergarments. It provides better thermal comfortduring cold weather and under wet conditions(sweating). Its surface profile is quite different ascompared to the surface profile of normal knitted fab-rics. Surface was made uneven using different knit-ting techniques, normally denoted by 1 ×1, 1×2, and
2×1 etc. Two types of knitting machines were used to
make rib; the first was circular double knit machine
and the second was flat double knit machine. In mostof the cases, circular knitting machine is used to pro-duce bulk quantity. Knitted rib made on circular knit-ting machine is used to make undergarments forexample vests, underwears, and body warmers etc.Knitted rib, which is manufactured using flat knittingmachines, is used to make waist and wrist bands andit is also attached with knitted shirts. This study is an effort to analyse the impact of surfaceprofile of knitted rib on thermal parameters (thermalconductivity, thermal resistance, and thermal absorp-
tivity). For this purpose, we developed 18 samples ofknitted rib using 100% polyester yarn and a flat knit-ting machine. There is no significant differencebetween the thicknesses of samples while major dif-ferences exist between their surface profile and pla-nar weight. Surface of knitted rib is divided into twomain categories (figure 1). Figure 1 shows that thereImpact of surface profile of polyester knitted rib structure
on its thermal properties
ASIF MANGAT LUBOS HES
VLADIMIR BAJZIK FUNDA BUYUK
REZUMAT – ABSTRACT
Impactul aspectului de suprafață al structurii de tricot patent din poliester asupra proprietăților termice
Scopul acestui studiu este de a evidenția efectul aspectului de
suprafață al structurii unui tricot patent asupra
conductivității, rezistenței și absorbției termice în condiții uscate. Epruvetele de tricot patent au fost realizate utilizând
fire de poliester 100%, având mase și grosimi distincte. În plus, a existat o mare varietate a aspectului de suprafață atricotului glat. Acest lucru a fost realizat prin utilizarea de reglaje diferite ale acelor la mașina de tricotat. Parametriitermici au fost testați utilizând un aparat de tip Alambeta. Epruvetele au fost păstrate în mod corespunzător într-un mediucontrolat timp de 24 ore. Rezultatele demonstrează că aspectul de suprafață al tricotului patent are un efect importantasupra parametrilor termici. Pe măsură ce scade distanța de contact, conductivitatea termică efectivă și absorbțiatermică scad, de asemenea, ceea ce este indicat pentru un confort termofiziologic mai bun. Acest studiu oferă o analizăprecisă a aspectului de suprafață al parametrilor termici, care este extrem de valoros pentru designerii de lenjerie decorp.
Cuvinte-cheie: patent, conductivitate, absorbție termică, parametri termici
Impact of surface profile of polyester knitted rib structure on its thermal properties
The reason for this venture is to recognize the effect of surface profile of knitted rib on thermal conductivity, thermal
resistance and thermal absorptivity under dry condition. Knitted rib specimens were made utilizing 100% polyester yarnhaving distinctive planar weight and thickness. In addition, there was a huge variety in surface profile of the rib. This wasaccomplished utilizing distinctive settings of needles on knitting machine. We tested thermal parameters utilizingAlambeta. Specimens were properly kept in a controlled environment for 24 hours. Results demonstrate that surfaceprofile of knitted rib has a noteworthy effect on thermal parameters. As the contact territory diminishes, effective thermalconductivity and thermal absorptivity diminishes as well, which is required for better thermo physiological comfort. Thisstudy gives a precise examination of surface profile of thermal parameters, which is highly valuable for internal articlesof clothing designers.
Keywords: rib, conductivity, thermal absorptivity, thermal parameters
103 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 1. Surface profile of knitted rib

are fins on the surface of knitted rib. These fins are
called vertical stripes (columns), also called wales.Rest of the area is called base of knitted rib fabric.Vertical columns are separated by missed stitches.On other side of knitted rib, the same pattern isrepeated but wales are alternatively arranged ascompared to front side. Knitted rib has no face andback because both sides are similar and either sidecan be used.
Knitted rib and thermal parameters
Thermal parameters (conductivity, resistance, absorp-
tivity) are very import
ant for better thermal comfort.
Thermal resistance is a vital property of material fab-rics and it is a subject of various studies. It relies onthe thermal conductivity of strands, thickness ofmaterial and course of action of yarn and filaments.Thermal conductivity shows the capacity of a materi-al to transfer heat. Thermal conductivity is anisotrop-ic in nature and to a great extent; it relies on thestructure of the material. The thickness of a materialprevents high temperature from passing through.
Thermal conductivity of knitted rib
Many studies have been conducted for various hypo-
thetical examinations of heat transfer through fabrics[1–7].
Their outcomes demonstrate that the proce-
dure of high temperature exchange through fabricsessentially happens by conduction, which is rep-resented by:
λΔTq=
(1)
h
Where qindicates heat flux [Wm–2], Tis temperature
[K], λshows thermal conductivity [Wm–1K–1] and h
represents thickness [m]. This was also affirmed in afar-reaching exploratory investigation of high temper-ature exchange through woven and nonwoven fab-rics, directed by Hes and Stanek, in which, theGrasshoff number (Gr) depicts the impact of free con-vection and it was found lower than 1,000 [8]. Theyfurther communicated that the extent of high temper-ature exchanged by radiation does not exceed 20%of the aggregate heat transfer. Heat transfer throughradiation also depends upon the temperature. At lowtemperature, heat transfer through radiation is quitelow because heat transfer through radiation dependsupon the fourth power of temperature. Thermal conductivity of dry fabrics needs to rely uponthe structure and properties of the yarns or filaments.Crow explains that two components, which play avery critical role in this context, are thickness of thefabric and fibre arrangements [6]. Parallel strandsbring about three times higher thermal resistance inconnection to filaments, which are perpendicular tothe fabric surface.
Thermal resistance
Thermal resistance R[m
2KW–1] is calculated using
the following equation:
hR= (2)
λWhere Rspeaks to the thermal resistance [m2KW–1],
his the fabric thickness [m], and λ is its thermal con-
ductivity [Wm–1K–1]. Equation 2 demonstrates that
thickness has a direct connection with thermal resis-
tance. Any change in thickness can change the ther-mal resistance of a fabric. The estimation of fabricthickness is very delicate, especially because of thecompressibility of the fabric. A minor change inweight will change the thickness of the fabric. Suchchange takes place because of high porosity and jut-ting strands on the surface of the fabric. Similarly,thick fabric having a smooth surface won't be essen-tially influenced by pressure.
Thermal absorptivity
Thermal absorptivity ( b) of fabrics was acquainted by
Hes, which provides warm feelings (heat transfer)
through limited cont
act of human skin with the fabric
surface [9]. Giving that the time of high temperaturecontact τbetween the human skin and the material is
shorter than a few seconds, the measured fabric canbe disentangled into semi-unbounded homogenousmass ρc [Jm
–3] and starting temperature t2. Unstable
temperature field between the human skin (withsteady temperature t
1) and fabric offers a relation-
ship, which focuses the heat transfer q[Wm–2]
through the fabric:
b(t1– t2)
q= (3)
π τ0.5
b= √λρc (4)
Where ρc [Jm–3] is the thermal capacity of the fabric
and the term b represents thermal absorptivity of fab-
rics. The higher the thermal absorptivity of the fabric,the cooler will be its inclination. In the material prax-
is, this parameter ranges from 20 Ws
0.5m–2K–1(for
fine nonwoven networks) to 600 Ws1/2m–2K–1 (for wet
fabrics).
Surface profile and thermal parameters
Xu et al. conducted a study to examine impact of
supercritical-pressure fluid flows and heat transfer ofmethane in ribbed cooling tubes [10]. His study wasfocused on regenerative engine cooling. For this pur-pose, he examined turbulent fluid flows and heattransfer of cryogenic methane in ribbed cooling tubesat a supercritical pressure of 8
MPa. The conclusion
of their study tells that a ribbed tube surface profileincreases significantly during the heat transfer pro-cess. The study revealed another fact that height ofrib should be suitable enough to facilitate heat trans-fer. Work of Xu et al. tells that the height of rib waleshelps in increasing heat transfer. But at the sametime, we cannot ignore the air trapped on the surfaceof rib. In case of rib, which is commonly used to make cloth-ing, fin height can increase surface area for moreheat transfer. In this case, the purpose of making ribis not fulfilled. We use rib to increase thermal resis-tance and maintain the human body temperature. It isonly possible if we enable rib to trap air, which helps
104 industria textila 2016, vol. 67, nr. 2 ˘

in increasing thermal resistance due to low thermal
conductivity of air. If air is not trapped, surface areawill increase, which will enhance heat flow from thehuman body. Özdil et al. studied the impact of yarn properties onthermal comfort of knitted fabrics [11]. Özdil et al.developed 1 ×1 knitted rib and identified the thermal
properties using various yarn varieties with distinctproperties. They took yarn count, yarn twist andcombing process as independent variables and ther-mal resistance, thermal absorptivity, thermal conduc-tivity, and water vapour permeability of samples asdependent variables. They used Alambeta andPermetest devices developed by Sensora CzechRepublic for testing. Their findings reveal that yarncount, yarn twist and combing process have signifi-cant impact on thermal absorptivity, thermal conduc-tivity, and water vapour permeability of 1 ×1 knitted rib
whereas yarn twist and yarn count decrease thermalresistance values and increase water vapour perme-ability values. Moreover, combing process has thesame effect on the thermal properties. Study of Özdilet al. does not include the surface profile of the rib.We can deduct from this study that better combingand high twist have a significant impact on thermalparameters only due to smooth profile of knitted rib.Although, there is no significant impact of theseparameters on the surface profile but still there is asubstantial influence on thermal parameters, whichshows that change in surface profile has a significantimpact on thermal parameters. Study of Taslim provides many new avenues of heattransfer and rib profile of any surface [12]. Taslimconducted a research to find out the fin effects on theoverall heat transfer coefficient in a rib-roughenedcooling channel. Rib structure is not only popular infabric; it is also widely used in heat exchangers usedin engines and hot bodies. The primary purpose is toincrease the heat flow and keep the engine body atrequired temperature. But in textile, rib structure,which is quite similar to fins on the heat exchangerbodies, is not used to increase heat flow from humanbody to the environment. Rather rib structure is usedto protect human body from heat loss and provide alayer of air to increase thermal resistance of the fabric.Taslim further describes the role of geometry of rib(fin) in heat transfer and calculation of heat transfercoefficient. In case of knitted rib, the geometry ofthe knitted rib is quite flexible and highly prone tochanges due to any pressure and stretch. Thischange does not allow developing heat transfer coef-ficient. Moreover, the height of fin is more important.According to Taslim, height plays a crucial role. Itcontributes to increasing the area that regulates theamount of heat transferred in a certain unit of time. Itis important to note that commonly used ribs havemaximum 2.5 mm thickness and their fin height isnormally in the range of 1–1.5 mm. From the work of Taslim, it is quite important to dealwith the question of air trapping in such a tiny gapbetween two rib wales. It may help transferring heat
instead of trapping air to increase thermal resistanceof knitted rib. A researcher can infer from figure 2 that
rib has three areas, base (space between two con-secutive fins), area of fin (height*width) and top of thefin [12]. Moreover, when airflow will move on the sur-face of the rib, there are chances of angled view. Taslim derived an equation to find out heat transfercoefficient. When it is applied on the base surface ofthe rib (projection surface), it will have the same ther-mal effects as that of the actual heat transfer coeffi-cient applied on total exposed area of the rib. Taslimconcludes that there is 20% possible error in calcu-lating the heat transfer coefficient using geometry ofthe rib. All the above discussion reveals that fins areused to increase the heat flow not to trap the air toimprove heat transfer area. Another aspect of knitted rib is the number of contactpoints between the human body and surface of thefabric. Pac et al. conducted a study on the process ofhuman hand touching the surface of a fabric whilethe skin had different temperature as compared tothe fabric [13]. During this process, heat transfersbetween the hand and the fabric. The first feeling iswarm-cool feeling. Pac et al. say that the significanceof warm-cool feeling depends on the contact pointsbetween the skin and the fabric. Fabric surface pro-file has strong dependency on structural parametersof fabric, which include physical and chemical prop-erties of fibre, knitting or weaving pattern, fabric thick-ness and porosity of the fabric. This study can belinked with the matter under discussion. Surface areaof knitted rib largely differs from a fully knitted fabric.Contact area between human hand and knitted ribranges from 20% to 80% depending upon the surfaceprofile of the knitted rib. As proved by Pac et al. num-ber of contact points provides a heat transfer chan-nel. In case of rib, these contact points are quite afew. Based on this point, knitted rib is considered asa useful fabric for wearing as under garment to con-trol the heat loss of human body [14].Work of Tarhan and Sarisik does not have any directlink with contact points between the human hand andsurface profile of the knitted rib [15]. It is about denim.Denim fabric produced from weaving machine hasa rough surface. But during washing, surface is
105 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 2. Rib Geometry

smoothened, which increases the contact points.
Higher contact points for trousers provide higher heattransfer, which is required during manual physicallabour. Thermal comfort depends upon the heat and mois-ture balance between human body and the environ-ment through our clothing. Various aspects of fabrichave a significant impact on thermal parameters.One of the most significant impacts is structure ofthe fabric [8, 16–20]. Knitted rib has a significant sur-face profile as compared to other plain fabrics.Considering this fact, it is obvious that knitted rib pro-vides a different kind of thermal comfort. Research by Hollies et al. on water transport mecha-nisms in textile materials reveals very unique results[21]. According to Hollies et al., the movement ofwater along fabrics depends on the laws of capillaryaction. They further say that water moves mainly inthe capillaries formed by the fibres in individualyarns. Their ultimate conclusion is: the speed of trav-el of water in these capillaries significantly dependson arrangements of fibres rather than depending onthe nature of fibres. Bogaty et al. have elaborated that thermal parame-ters also depend upon the arrangements [22]. Rib hasquite distinct fibre arrangements and as compared toa fully knit jersey fabric. This arrangement has a sig-nificant correlation with the thermal conductivity ofthe fabric. Keeping this factor in view, we can derivethat the rib has a different thermal conductivity andchanged thermal resistance, which a wearer needs.All the above discussion depicts that arrangement offibre and yarn has a significant impact on thermalparameters. As discussed in previous pages, thereare two main issues linked with knitted rib and ther-mal parameters. First is surface profile of knitted rib,which does not have enough height of fins to trap airunder even minor pressure to provide thermal resis-tance due to presence of air while in the secondcase, heat flow can be quite low due to the less num-ber of contact points between human body and knit-ted rib.
EXPERIMENTAL PART
Sample description
Weft-knitted rib, knitted on a flat knitting machine,
was used for this study in order to verify the imp
act of
distinct rib structures on thermal parameters (thermalconductivity, thermal resistance, thermal absorptivity)in a dry state. Knitted rib consists of one type of yarn.It has similar surface profiles on both sides. It is com-monly used to make collars, cuffs or waistbands. Insome cases, undergarments are made using rib.Most common is vest, which provides better thermalfeeling. Attires made up of rib are also called thermaldresses due to their capability to maintain body heatin cold climate. Most common materials for knitted ribare cotton, polyester and polypropylene in some cases.Eighteen types of knitted rib having diverse struc-tures and surface profiles were used for testing pur-poses. See table 1.Testing procedure
The determination of thermal parameters (thermal
conductivity
, thermal resistance, thermal absorptivity)
requires the use of a special testing instrument thatenables a researcher to record a measurement.Many studies have used Alambeta (Sensora CzechRepublic), which gives results in less than three min-utes. The Alambeta is computer-controlled, semiau-tomatic, non-destructive thermal parameters testingdevice along with thickness tester for testing textilefabrics. The biggest advantage of the Alambeta test-ing is that the instrument immediately displays thethermal parameters along with the thickness levels ofthe tested fabrics. Selection of Alambeta is based onits efficient and effective use along with its applicationin many studies [3, 24–26]. All the samples were put openly in a flat position inthe testing lab. In testing lab, the temperature rangedbetween 25–26°C and relative humidity was in therange of 20–22. It was done to give a uniform treat-ment to all the samples for more accurate results.
RESULTS AND DISCUSSION
The primary objective of this study is to find out the
correlation among cont
act area, porosity, planar
weight and thermal parameters.
Contact points and thermal parameters
Contact points of rib define the area which touches
the human hand in the absence of pressure. It is cal-culated using the following equation:
FC=
×100 (5)F+ B
where Cis the contact area (%), F – the area of fin
on top (elevated course s) and B– the area between
106 industria textila 2016, vol. 67, nr. 2 ˘BASIC CHARACTERISTICS OF KNITTED RIB
Sample No. Rib types Planar weight
(gm2)
1 1.1 481
2 1.2 400
3 2.1 541
4 2.2 560
5 2.3 462
6 3.1 523
7 3.3 477
8 3.4 471
9 4.1 485
10 4.2 548
11 4.3 540
12 4.4 540
13 1.1 378
14 2.1 422
15 3.1 447
16 4.1 474
17 5.1 501
18 6.1 470Table 1

two adjacent rows of courses. This area was calcu-
lated with the help of a computer-controlled camera.Area of contact ( C) depends upon the type of rib
structure. Normally, notations used for rib are 1 ×1,
1×2, and 2 ×1 etc. Figure 2 shows that on knitted rib,
surface is divided into two portions; base and wale(or fin). Thickness of base is almost half of the thick-ness at the point of fin. When someone touches theknitted rib, only fin touches the s kin. This is a tech-
nique to reduce the contact points between thehuman skin and the fabric.
Figure 3 tells that there is a significant correlationbetween thermal conductivity and contact area (R
2
0.58). It proves the observation of Tarhan and Sarisik[15]. Moreover, it shows that more contact pointsmean that there is less area for air between thehuman skin and knitted rib. Thermal conductivity ofpolyester is between 0.3–0.4 [Wm
–1K–1] and thermal
conductivity of air is 0.026 [Wm–1K–1] [27]. It also
proves that less contact area shows that there is morespace for air between human skin and knitted rib sur-face. From these results, we can conclude that lesscontact area will maintain human body temperature. Figure 4 shows a weak relationship between thermalresistance and contact area (R
20.42). It may be due
to the intervening variable, which is thickness. OnAlambeta, we exert a pressure of 1000 Pa. It isrequired to make a solid contact between the plateand the fabric. Knitted rib is quite flexible and easy tocompress. Due to this compressibility, error in mea-suring the exact thickness is possible. Figure 5 depicts a strong correlation between thermalabsorptivity and contact area (R
20.96). Thermal
absorptivity indicates the warm-cool feeling. Figure 5shows that as the contact point’s increase, thermalabsorptivity also increases or we can say that there isa direct relation between the number of contactpoints and thermal absorptivity. Its significance isobvious from R square value. Higher thermal absorp-tivity value is an indicator of coolness, which resultsin heat flow from human skin, whereas low thermalabsorptivity values indicate a warm feeling.
CONCLUSION
Results demonstrate that there is a nonstop incre-
ment in thermal conductivity with the increment incont
act focus. Contact focus is a point where human
skin and fabric surface touches. Thermal conductivi-
ty of polyester is much higher than the thermal con-ductivity of air. Viable thermal conductivity of a fabricis not the same as thermal conductivity of polyesterand air. It is not the aggregate of the individual ther-mal conductivity. Fabric contains polymer, dampnessand air. Thermal conductivity of fabric is a conse-quence of consolidated impact of air, dampness andpolymer. This is a vital result of the study, which willguide dress architects to plan internal apparels hav-ing least contact focuses to maintain the human bodytemperature. Second result of the study expresses afact that there is limited connection between thermalsafety and contact focus. It is essentially limitedbecause thickness values vary in different varietiesof the fabric and there was no variety in knittingmachine set up. In any case, it is evident that there isa change in thermal safety because of progress inthermal conductivity. We additionally found out thatthere is a significant and noteworthy relationshipbetween contact region and the thermal absorptivity.Higher thermal absorptivity allows skin to feel coolvibes. Rib structure gives less contact territory. It isprimary reason of choice of knitted rib fabric for man-ufacturing undergarments.
ACKNOWLEDGEMENT
This research work is financially funded by project SGS
21098 Czech Republic.
107 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 3. Thermal conductivity and contact area
Fig. 4. Thermal resistance and contact area
Fig. 5. Thermal absorptivity and contact area

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Authors:
ASIF ELAHI MANGAT1
LUBOS HES1
VLADIMIR BAZIKH1
FUNDA BUYUK2
Technical University of Liberec, Faculty of Textile Engineering,
1Department of Textile Evaluation,
2Department of Textile Clothing,
Studentska 2, Liberec, 461 17, Czech Republic
Corresponding author:
ASIF MANGAT
e-mail: asifmangat@gmail.com

INTRODUCTION
Cotton is the most used natural fiber in the textile
industry globally because it is inexpensive, absor-bent, breathable and sof t. However
, different chemi-
cal modifications have been studied for improvementof the wettability, dyeability, chemical affinity, creaserecovery, hydrophilicity, and functional properties ofcotton textiles. Cotton fibers can be dyed using anio-nic dyes easily, but usually the common processes ofcotton dyeing require large amounts of salt and alkaliwhich mostly remain in the dye bath after the dyeingand may harm the environment [1–2]. The reason for using the electrolytes in the dyeingprocess is to overcome the repulsion forces occurringbetween the negatively charged cotton fibers and theanionic dye molecules [2]. Improving the substantivi-ty of cotton toward anionic dyes by surface modifica-tion techniques, it is possible to reduce the need forelectrolyte in the dyebath, and increase the dyebathexhaustion [3].Salt free dyeing of cotton has been an interestingsubject for many researchers. In this regard, the mostcommon method used in the literature has been theintroduction of cationic moieties to cotton fiber (catio-nization) to interact with anionic dye molecules in thedyeing process and increase the dyeing colorstrength and improve the wash fastness [4–6].Tutak and Ozdemir applied four different commercial
quaternary ammonium salts on cotton using a simplepad-dry method. The untreated and cationized cottonsamples were dyed with a reactive dye. Their resultsshowed that in comparison with the untreated cottondyed with traditional method, the exhaustion and fixa-tion values of the cationized cotton fabrics were bet-ter having higher degree of wash fastness [2].In another study, Patino et al investigated the singleand combined effects of corona treatment and catio-nization of cotton using an epihalohydrin on reactivedyeing of the modified fibers. Cationization of cottonincreased the color strength of the dyed sample by80% while this increase was only 14% for the coronatreated fabric. Plasma treatment previous to cationi-zation caused no significant improvement in the colorstrength of the dyed sample [7].Montazer et al studied the salt free dyeing of cationi-zed cotton using three different reactive dyes. Thecationization was performed using 2,3-epoxypropyl-trimethylammonium chloride by a pad-batch methodand the cationized cotton samples were dyed withmonochloro triazine, dichloro triazine and vinyl sul-phone reactive dyes. The dyeability of the cottonsamples with all reactive dyes was significantlyimproved without using salt. The light fastness of thecationized samples was improved while the washand rub fastness properties remained unchanged [8].Salt free neutral dyeing of cotton with anionic dyes using plasma
and chitosan treatments
AMINODDIN HAJI SAYYED SADRODDIN QAVAMNIA FARHAD KHOSRAVI BIZHAEM
REZUMAT – ABSTRACT
Vopsirea fără săruri a bumbacului cu coloranți anionici utilizând tratamentele cu plasmă și chitosan
Modificarea ecologică a fibrelor de bumbac, în scopul îmbunătățirii cap acității de vop
sire cu coloranți anionici, a fost
scopul principal al acestui studiu. Biopolimerul chitosan a fost selectat pentru introducerea radicalilor cationici în fibrele
de bumbac. Tratamentul cu plasmă a fost utilizat pentru a produce zonele funcționale în scopul atașării chitosanului desuprafața fibrelor. În acest studiu, chitosanul a fost aplicat pe țesătura de bumbac folosind pre-tratamentul cu plasmă cuoxigen. Prezența chitosanului pe suprafața fibrelor de bumbac a fost evidențiată pe baza imaginilor SEM. Mostrele debumbac netratate și tratate cu chitosan au fost vopsite cu coloranți acizi și direcți. Au fost studiate efectele sării (sulfatu lui
de sodiu), timpului de vopsire și concentrației inițiale de colorant asupra rezistenței vopsirii probelor netratate și tratatecu chitosan.
Cuvinte-cheie: plasmă, chitosan, bumbac, fără conținut de sare
Salt free neutral dyeing of cotton with anionic dyes using plasma and chitosan treatments
Environmentally friendly modification of cotton fibers with the aim of improvement of its dyeability with anionic dyes was
the main purpose of the current study. Chitosan biopolymer was selected for introduction of cationic moieties to cottonfibers. Plasma treatment was employed to produce the functional sites for attachment of the chitosan to the surface ofthe fibers. In this study, chitosan was applied on cotton fabric using oxygen plasma pre-treatment. The presence ofchitosan on the surface of cotton fibers was approved by SEM images. Untreated and chitosan treated cotton sampleswere dyed with acid and direct dyes. The effects of salt (sodium sulfate), dyeing time, and initial dye concentration onthe color strength of raw and chitosan treated samples were studied.
Keywords: plasma, chitosan, cotton, dyeing, salt free
109 industria textila 2016, vol. 67, nr. 2 ˘

Cationization can improve the natural dyeing of cot-
ton fibers as well. In a recently published study, it wasfound that the cationization of cotton fabrics byexhaustion method, significantly improved the dyea-bility and fastness properties of cotton fabrics dyedwith the aqueous extract of Vitis Vinifera L. leaves [5].
Haddar et al investigated the salt free dyeing of catio-nized cotton fabrics with leaves of fennel (Foeniculumvulgare ) and Hibiscus mutabilis (Gulzuba) as two
sources of natural dyes and optimized the dyeingprocess using response surface methodology [9–10].Application of other chemicals like dendrimers andhyperbranched polymers has enhanced the dyeabili-ty of cotton using direct and reactive dyes leading tosalt free dyeing [4, 11–13]. Chitosan as a natural bio-polymer can be applied on cotton by different techni-ques and enhance its dyeability with anionic dyes[14]. Coating of cotton fiber with chitosan can intro-duce amine groups to the fiber leading to the possi-bility to dye the cotton fibers with acid dyes [15].Grafting of acrylic acid on cotton fibers using plasmapre-treatment improved the dyeability of the modifiedfabric with natural cationic dye, berberine [16].Grafting of ethylenediamine and triethylenetetramineon cotton fibers pretreated with air and argon plasmaenhanced the dyeability of cotton fabric with aciddyes [17]. In this paper, cotton fibers are first activated usingoxygen plasma and then grafted with chitosan. Themain objective is to explore the effects of plasma andchitosan treatments on the dyeability of modified cot-ton fabric without using salt and in neutral medium.
EXPERIMENTAL WORK
Materials and Methods
Plain weave 100% cotton fabric (100 g/m², yarn
count Nm = 40) was obt
ained from Mazandaran
Textile Co., Iran. Medium molecular weight chitosan(75-85% deacetylated), Triton X-100 (nonionic sur-factant) and sodium sulfate were purchased fromSigma Aldrich (USA). C.I. Acid red 88 and C.I. Directorange 26 dyes were obtained from Alvan SabetCompany, Hamedan, Iran. The chemical structures ofthe dyes are shown in figure 1.
Plasma treatment: Cotton samples were pretreatedusing radio frequency (13.56 MHz) low pressure plas-ma equipment (model: Junior plasma, Europlasma,Belgium) with oxygen gas. The sample chamber wasevacuated to 100 mTor and maintained at this pres-
sure during the treatment. Oxygen with a flow rate of100 sccm (Standard Cubic Centimeters per Minute)was used in the plasma treatment process. Plasmawas generated at 150 W for five minutes. Then,atmospheric air was introduced into the chamber andthe plasma treated sample was removed.Chitosan treatment: Plasma treated samples wereimmediately impregnated in 0.5% w/v solution of chi-tosan containing 1% v/v acetic acid for 30 min. Thenthe samples were padded with 100% wet pick up anddried at 80 °C for 30 min. The dried samples werethoroughly washed with a solution containing 1% w/vTriton X-100 at 50 °C for 15 min to remove non-reac-ted chitosan from the surface of the fabric samples.Dyeing: Dyeing of the raw and chitosan treated sam-ples was performed using different amounts of directand acid dyes (0.5–2 % owf) in the presence ofvarying amounts (0–10 % owf) of glauber’s salt (L:G= 40:1) at the natural pH of the solution (around 7).
The dyeing was started at 30°C and the temperaturewas raised to 50°C) at the rate of 2°C per minute.Then the samples remained in that condition with stir-ring for different times (30–120 min), and then rinsedand air dried.Color strength measurements: The reflectance ofdyed samples were measured on a Color-eye 7000Aspectrophotometer using illuminant D65 and 10° stan-dard observer. Color strength (K/S) of each dyedsample was calculated using kubelka-munk equation:
K/S= (1–R)
2/ 2R (1)
Where Ris the observed reflectance at wavelength
of maximum absorbance, K– the absorption coeffi-
cient and S – the light scattering coefficient.
Color fastness test: Color fastness to washing wasmeasured according to ISO 105-C01:1989(E) standard.Scanning electron microscopy (SEM): Scanning elec-tron micrographs were taken on an AIS2100 scan-
ning electron microscope (Seron Technology, SouthKorea) to study the effect of plasma and chitosantreatments on the surface morphology of cotton fibers.
RESULTS AND DISCUSSION
SEM investigations
Figure 2 shows the SEM images of raw, plasma trea-
ted and chitosan coated cotton fibers respectively
.
Comparing the micrographs of raw and plasma trea-ted fibers it is evident that serious etching has beendone on the cotton fibers by oxygen plasma.Comparing these two samples with chitosan treatedfibers, it can be seen easily that chitosan has beensuccessfully grafted on cotton fibers.
Effect of dye concentration on color strength
To study the color build-up of both direct and acid
dyes on raw and chitosan treated cotton fabrics,samples were dyed with four dif
ferent concentrations
of each dye. Figures 3 and 4 show the effect of con-centration of direct and acid dyes on the colorstrength of raw and chitosan treated samples res-pectively. It can be seen that the concentration of
110 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 1. The chemical structures of the C.I. Direct
orange 26 (top) and C.I. Acid red 88 (bottom)

111 industria textila 2016, vol. 67, nr. 2 ˘both dyes in the dyebath has an increasing effect on
the color strength of the dyed samples. Using thesame concentration of the dye in the dyebath, thesamples dyed with the direct dye produced a muchhigher color strength comparing with the samplesdyed with the acid dye.The color strengths of chitosan treated samples arehigher than the raw samples for both dyes and allconcentrations. This improvement in dye absorptionis due to the fact that chitosan treatment on cottonfabric provided more dye sites for absorption of theanionic dyes than the raw fabric. The application ofchitosan improved the absorption of the dye molecu-les thanks to its cationic characteristic. Chitosan fixedon the surface of the cotton fibers makes the cottoncellulose positively charged. As a result, chitosantreated cotton is able to absorb anionic dyes throughthe ionic interaction between dye-anions and fiber-cations mechanism [18].
Effect of salt concentration on color strength
Figures 5 and 6 show the effect of salt concentration
on the color strength of raw and chitosan treatedsamples dyed with direct and acid dyes respectively
.
As expected, the addition of salt increased the dyeuptake for both raw and chitosan treated samples.However, the chitosan treated samples absorbedmuch higher amount of direct and acid dyes compa-red to raw fabrics. It is well-known that celluloseacquires negative charge when dipped in water anddirect and acid dyes acquire anion in bath resultingrepulsion between dye and cellulose. As a result,addition of electrolyte promotes dye uptake throughreduction in zeta potential and promotes substantivi-ty of dye. All direct dyes require salt at varying con-centrations for better exhaustion on cellulosic fibers[19]. The presence of chitosan on the surface of thefibers makes the fiber’s surface cationic and reducesthe need for electrolyte in dyeing. For both dyes,addition of only 2% owf of salt in the dyebath of chi-tosan treated samples produced the same or highercolor strength as the raw cotton dyed in the presen-ce of 10% owf salt. So, it can be concluded that plas-ma and chitosan treatment can enable the cottonfabric to be dyed with direct and acid dyes without theneed for electrolyte at low temperature.
Effect of dyeing time on color strength
Raw and chitosan treated samples were dyed with
both dyes in the presence of 5% owf salt and withoutit. Figure 7 shows the ef
fect of dyeing time on the
color strength of raw and chitosan treated sampleswhen dyed with the direct dye. As expected, the color strength increased with pro-longed time up to 90 min for all samples dyed withthe direct dye. It seems that the optimum time fordyeing with C.I. Direct Orange 26 is 90 min and morecontact with water molecules may cause the hydroly-sis of the dye molecules resulting in reduced dyeabsorption.As shown in figure 8, the optimum time for dyeing ofboth raw and chitosan treated cotton fabrics with theacid dye is 30 min. In this case, increasing the dyeingtime caused considerable decrease in the colorstrength of the dyed samples. However this sensitivi-ty is more pronounced for the raw samples and the
Fig. 2. SEM images of raw (left), plasma treated (middle) and chitosan coated (right) cotton fibers
Fig. 3. The effect of direct dye concentration on color
strength of raw and plasma treated samples
(without salt, 30 min, 50 °C)
Fig. 4. The effect of acid dye concentration on color
strength of raw and plasma treated samples
(without salt, 30 min, 50 °C)

112 industria textila 2016, vol. 67, nr. 2 ˘chitosan treated samples were dyed with higher color
strength at longer dyeing times when the direct dyewas applied.
Washing fastness
Since the most important problem associated with
the application of direct dyes on cellulosic fabrics isthe poor wash fastness, the possibility to increase thewash fastness of the selected dyes was one of thegoals of this study
. Table 1 shows the wash fastness
properties of different dyed samples. The fastness towashing was increased for both dyes when chitosanwas applied on cotton samples. The ionic attractionbetween the cationic chitosan coated cotton and theanionic dye molecule increased the fastness of thecolor for this samples in comparison with the raw cot-ton samples which possess negative charge in con-tact with water causing the repulsion of the dye mole-cules and low wash fastness. CONCLUSION
Cotton fabric was successfully coated with chitosan
using oxygen plasma as a pretreatment.
The chito-
san treated samples showed better dyeability besi-des good build up with direct and acid dyes used inthis study. The application of chitosan on cotton fabricreduced the need for electrolyte in the dyebath mar-kedly. The optimum dyeing time for the direct and
Fig. 5. The effect of salt on the color strength of raw
and chitosan treated samples dyed with direct dye
(1% owf dye, 30 min, 50 °C)
Fig. 6. The effect of salt on the color strength of raw
and chitosan treated samples dyed with acid dye
(1% owf dye, 30 min, 50 °C)
Fig. 7. The effect of dyeing time on the color strength
of raw and chitosan treated samples dyed with the direct
dye without (top) and with 5% owf salt (bottom)
Fig. 8. The effect of dyeing time on the color strength
of raw and chitosan treated samples dyed with the acid
dye without (top) and with 5% owf salt (bottom)
WASH FASTNESS OF RAW AND CHITOSAN TREATED
SAMPLES DYED WITH 1% OWF DIRECT AND ACID
DYES (WITHOUT SALT, 30 MIN, 50 °C)
SampleWash fastness
Direct dye Acid dye
Raw cotton 3 2–3
Chitosan treated cotton 44Table 1

acid dye was 90 and 30 min respectively. The wash
fastness of both dyes was significantly higher in caseof chitosan treated samples. The method used in thisstudy, can increase the dye uptake and wash fas-tness of direct and acid dyes on cotton fabric withoutthe use of salt, alkali or acid. Plasma treatment is anenvironmentally friendly process and chitosan is abiodegradable and safe biopolymer with antibacterialactivity. So this method can be considered as anenvironmentally friendly process for modification ofcotton fabrics to enhance their dyeing, fastness andfunctional properties.
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Author:
AMINODDIN HAJI1
SAYYED SADRODDIN QAVAMNIA1
FARHAD KHOSRAVI BIZHAEM2
1Department of Textile Engineering, Birjand Branch, Islamic Azad University
2Department of Art, Birjand Branch, Islamic Azad University
Birjand, IRAN
e-mail: ahaji@iaubir.ac.ir, qavamnia@gmail.com, farhadkhosravi121@yahoo.com
Corresponding author:
AMINODDIN HAJI
ahaji@iaubir
.ac.ir

INTRODUCTION
Polyamides are polymers which contain recurring
amide group
s as integral parts of the main polymer
chain [1]. The most common synthetic polyamidesare polyamide 6 (Nylon 6) and polyamide 66 (Nylon66). The annual world production of polyamide is 4million tons [2]. Nylons are fairly resistant to chemicalattack. They are attacked by acids, bases, and byreducing and oxidizing agents only under extremeconditions. They are unaffected by biological agents,but at elevated temperatures or in the presence ofsunlight they will undergo oxidative degradation withyellowing and loss of strength [3]. Nylon fibers arewidely used in apparel such as hosiery, blouses,dresses, foundation garments, lingerie, underwear,raincoats, ski apparel, windbreakers, swimwear, andcycle wear. They have also been used for house fur-
nishings such as bedspreads, carpets, curtains, andupholstery [4]. They should be scoured with mild agi-tation at a moderate temperature of 50–60 °C toremove any impurities containing certain oils andgreases. Nylon is a white fiber as produced by themanufacturer and so seldom requires bleaching [1].
A great disadvantage of some synthetic fibers is theirlow surface energy. This causes poor wettability anddyeability so different surface modification tech-niques have been studied [5]. Among these surfacemodification techniques, enzymatic modification ofpolyamide fibers has also been studied scientifically.For example, Silva et al. (2007) studied the modifica-tion ability of cutinase and protease enzymes. Theyalso tested the effect of mechanical agitation. Theyreported that protease enzymes as well as cutinaseDyeing of enzymatically modified polyamide fabrics with natural dyes
M. İBRAHIM BAHTIYARI HÜSEYIN BENLI
REZUMAT – ABSTRACT
Vopsirea țesăturilor din poliamidă modificate enzimatic cu coloranți naturali
Fibrele sintetice au o cerere tot mai ridicată, determinată de creșterea populației la nivel global. Datorită acestui fapt,
studiile referitoare la fibrele sintetice au devenit populare.
Aceste studii abordează în special modificarea fibrelor
sintetice pentru a obține proprietăți asemănătoare fibrelor naturale și pentru a îmbunătăți capacitatea de vopsire afibrelor. Scopul acestui studiu a fost de a investiga oportunitățile de modificare a fibrelor de poliamidă cu enzime de tippepsină și tripsină și a capacității de vopsire cu surse naturale de vopsire. În prezent, există multe metode diferite de amodifica fibrele de poliamidă, cu toate acestea, modificarea enzimatică a fost examinată în acest studiu. Estebinecunoscut faptul că procesele enzimatice sunt, în general, ecologice, ceea ce a determinat ca la finisarea țesăturilorde poliamidă să se utilizeze în operația de vopsire tot surse naturale. Având în vedere aceste argumente, în acest studiuau fost folosite diferite enzime de protează pentru modificarea mostrelor de poliamidă. Țesăturile modificate au fostvopsite cu diferiți coloranți naturali pentru a investiga modificarea capacității de vopsire. În acest scop au fost analizateeficiența vopsirii și valorile CIE L*a*b*. Mai mult, modificarea suprafeței și modificările structurale au fost, de asemenea,investigate cu ajutorul SEM și FTIR. S-a constatat că enzimele testate nu au afectat semnificativ capacitatea de vopsirea probelor de poliamidă cu surse naturale de vopsire, totuși aceste surse de vopsire naturale reprezintă o alternativăpentru vopsirea probelor de poliamidă deoarece, cu excepția rezistenței la lumină, celelalte tipuri de rezistență s-audovedit a fi satisfăcătoare.
Cuvinte-cheie: poliamidă, enzimă, protează, coloranți naturali, eficiența vopsirii
Dyeing of enzymatically modified polyamide fabrics with natural dyes
Synthetic fibers are in increasing demand because of the increasing world population. As a result of this, studies on
synthetic fibers have become popular. These studies are especially focused on the modification of synthetic fibers togain natural fiber like properties and to improve the dyeability of the fibers. The aim of this paper was to investigate themodification opportunities of polyamide fibers with pepsin and trypsin enzymes and the dyeability with natural dyesources. At present there are many different methods to modify the polyamide fibers, however enzymatic modificationwas examined in this study. As well known, enzymatic processes are generally environmentally friendly so it wasplanned to complete the finishing of polyamide fabrics by dyeing them via natural dye sources. In the light of thesearguments different protease enzymes were used for the modification of polyamide samples in this study. The modifiedfabrics were dyed with different natural dyes to investigate the change in dyeability. For this aim color efficiencies andCIE L*a*b* color values were analyzed. Moreover, the surface modification and structural changes were alsoinvestigated by the help of SEM and FTIR. It was found that the tested enzymes did not significantly affect the dyeabilityof the polyamide samples with selected natural dye sources however these natural dye sources was found as analternative for the coloration of polyamide samples and except light fastnesses, the fastnesses of the dyed fabrics werefound sufficient.
Keywords: Polyamide, enzyme, protease, natural dyes, color efficiency
114 industria textila 2016, vol. 67, nr. 2 ˘

enzymes have the capacity to modify polyamide fab-
rics [6]. In another study, the usability of cutinaseenzyme was introduced for polyethylene terephtha-late and polyamide 6,6 fibers [7]. El-Bendary et al.(2012) studied the enzymatic surface hydrolysis ofpolyamide fabric by using protease enzymes. Firstly,they isolated different bacillus strains to produce pro-tease enzymes. They then showed that by enzymat-ic modification of polyamide the hydrophilicity andcationic dye affinity can be improved [8]. The modifi-cation of polyamide 6.6 fabrics by a mixture of prote-olytic and lipolytic enzymes was also studied and theefficiency of lipase and protease enzymes was alsoreported [9]. Differently, in this study, we tried to com-bine the enzymatic modification of polyamide fabricswith natural dyeing. Growing awareness of theorganic value of eco-friendly products has increasedinterest in the use of textiles dyed with eco-friendlynatural dyes [10]. In this study, it was planned tointroduce an environmentally friendly process for themodification and dyeing of polyamide fabrics. For thisaim two different natural dye sources, namelypomegranate peels and walnut barks, were used.Pomegranate is native to Western Asia, and is morecommonly grown in Iran, Northeastern Turkey andthe region of the South Caspian Sea. It has been cul-tivated science early antiquity [11]. The major color-ing component in pomegranate is tannin and ellagicacid which are extracted from the fresh and driedpeels [12]. The walnut is one of the oldest cultivatedfruits in the world. It was brought to Europe in the16th century and to America in the 17th century.Walnut belongs to the Juglandaceae family, juglansvariety Juglans regia L. [13]. Extracts of walnutleaves and the dried shells of green walnut can beused for dyeing textiles such as wool, silk, nylon, andpolyester and cellulose fibers [14].
EXPERIMENTAL
Materials
In this study, 100% polyamide 6.6 fabrics with a
weight of 150 g/m
2were used for the experiments.
For the modification of the polyamide samples trypsin(Mp Biomedicals) from Porcine Pancreas and pepsin
(Merck) from Porcine Gastric Mucosa were used. As
natural dye sources Pomegranate peels and walnut
barks which were cultivated in the Anatolian region
were used. The walnuts’ fresh green barks andpomegranate peels were collected and dried in theshade, then these barks were ground and useddirectly in the dyeing of polyamide as a natural dye.
Methods
The polyamide samples were firstly washed with a
nonionic washing agent at 60 
°C for 30 minutes prior
to the enzymatic modification. In this way it wasplanned to clean the fabrics and prepare them for theapplication of the enzymes. Enzymatic Modification: The modification ofpolyamide samples was managed with the use of twodifferent protease enzymes (trypsin and pepsin) indifferent concentrations (0-1-3-5%). The duration ofthe modification was set to 60 or 120 minutes. The
details of the modification process are given in figure1. For the selected samples, the FTIR analysis withPerkin Elmer Spectrum 400 and scanning electronmicroscopy (SEM) analysis with LEO 440 instrumenthave been conducted to see the effect of the pro-tease enzymes on polyamide samples. Moreover, thesamples modified with the same enzyme for thesame duration and the unmodified (blank) one weredyed with natural dye sources in the same bath.Natural Dyeing procedure: The modified and
unmodified (blank) fabrics were dyed with two differ-ent natural dye sources. During the study, dried andground pomegranate peels and the green barks ofwalnuts were used as natural dye sources. For thedyeing of polyamides, the concentration of naturaldye sources (pomegranate peels and walnut barks)to the fabric was set to 100% (w/w) in the dye bath.Dyeing was managed by using these natural dyesource powders without any mordanting process.First, the fabrics modified with the same enzyme forthe same duration and the blank sample (treated inthe same conditions but without enzymes) weresoaked in the same dye bath at pH 6 with the dye
plants. Then the samples were heated in a dye bathratio of 1:30 to 100 °C and at this temperature theprocess was carried out for 60 minutes. After dyeing,the bath has been cooled and the fabrics were rinsedand washed. Subsequently, the natural dyedpolyamide samples were dried at room temperature.The dyed fabrics were evaluated in terms of colorefficiencies (K⁄S) and CIE L*a*b* color space values
by using a Konica Minolta 3600d spectrophotometer(D65/10°). The color efficiencies of the modified fab-rics were then converted to relative color strength tosee the change simply by equation 1.
Relative Color Strength (K/S%) =
= K/S
modified * 100 / K/Sunmodified (blank)(1)
The dyed samples were also investigated in terms ofcolor differences. For this aim color differences (DE)between the enzymatically modified and blank pro-cessed fabrics have been investigated by the use ofequation 2.
Delta E (DE) =
=
[ (Delta L)2+ (Delta a)2+ (Delta b)2 ]0,5(2)
115 industria textila 2016, vol. 67, nr. 2 ˘Fig. 1. Enzymatic modification process for:
(a) trypsin and (b) pepsin
a
b

Moreover, the washing fastness (ISO 105-C10 test
condition of Test A (1), 2006) and light fastness (ISO105-B02, 1994) of the dyed samples were also test-ed [15, 16]. RESULTS AND DISCUSSION
Effect of Enzymes on Polyamide Fibers
In the first step of the study the effect of enzymes on
polyamide fibers was tested. For this purpose theSEM photographs and FTIRs of the modified fabricswere comp
ared with the untreated fabric.
Figure 2 shows the SEM views of the untreated andenzymatically treated fabrics. It was observed that nosignificant surface modification is present due to theprotease enzymes; however, a somewhat peelingabrasion resulted from the enzymatic modification. Inaddition to this limited surface modification in order tosee the chemical structure changes the FTIRs of thesame samples were also collected (figure 3).In general the FTIRs of the tested samples wereseen to be similar and no significant differences,except for the band at 1635 cm
–1, were observed. On
the other hand in terms of the enzymatic modificationby proteases it is expected that the peptide bonds willbe hydrolyzed and accordingly the amide bands willbe changed. It was reported that the presence of theamide carbonyl group (Amide-I band) and N-H bend-ing vibration (Amide-II band) are indicated by astrong band in the region of 1675–1620 cm
–1 and the
band at 1560–1520 cm–1respectively [17]. In this
respect it was found that T% at 1635 cm–1, which is
thought to be related with Amide-I, was increased
after enzymatic modification. It was thought that thischange could be related with the hydrolyzing of thepeptide bands by the enzymes. As a result of this
hydrolysis, free amino groups which are responsiblefor the dyeability of polyamide, especially with aciddyes, can be come out. To see the effect of thischange on the dyeability of the polyamide fibers withnatural dyes, the fabrics were dyed with walnut barks
116 industria textila 2016, vol. 67, nr. 2 ˘Mag. = 800X Untreated Fabric
Mag.= 4.00KX
Mag. = 2.00KX Fabric treated with 5% Pepsin
Mag. = 5.00KX
Mag. = 5.00KX Fabric treated with 5% Trypsin
Mag. = 3.00KX
Fig. 2. SEM photographs of untreated and enzymatically
modified fabrics
Fig. 3. FTIRs of untreated and enzymatically modified fabrics

and pomegranate peels. As a result it can be
said that enzymes can modify the polyamidefibers somewhat as has been previouslyreported by different authors.
Effect of enzymes on dyeability of
polyamide fabrics with natural dyes
•Dyeing with walnut barks
In this part of the study the fabrics modified
with different enzymes at different concentra-tions and durations were dyed directly withdried and ground walnut barks at pH 6. It was
observed that polyamide samples can be col-ored with walnut barks and very dark desatu-rated orange colors and brown shades can beobtained (table 1).Table 1 also shows the extent to which thecolor shades were changed depending on theenzymatic process conditions. To see thesechanges the CIE L*a*b* color values of thesamples were also collected and given intable 2.Table 2 shows that depending on the enzy-matic process conditions the color values canbe changed but this change was found to belimited. In other words, the main colorsobtained were the same but the shade can be alteredby the enzymes. One of the most significant colorshade changes was observed in the fabrics modifiedfor 60 minutes with 5% pepsin enzyme. The color dif-ference (Delta E) according to the blank process (60minutes modified with 0% pepsin enzyme) was foundto be 0.88. In modification with trypsin enzymes themost significant color shade difference was observedin the fabrics modified for 120 minutes with 5%trypsin. In that case the color difference according tothe blank process (120 minutes modified with 0%trypsin enzyme) was found to be 1.84.
Additions to the color values of the dyed samples, thecolor efficiencies of the fabrics were also collected.The obtained color efficiencies were converted to therelative color efficiency as explained in equation 1. Inother words, each dyed sample was compared withits blank condition (fabric modified in the same con-ditions but without the use of any enzyme) and in thisway the relative color efficiency was obtained.Figure 4 shows that pepsin based enzymatic modifi-cation of polyamide samples did not have a signifi-cant effect on the color efficiencies and in somecases the color efficiency of the dyed samples waslower when compared with their blank counterparts.On the other hand, with the use of trypsin enzyme thecolor efficiencies were increased when compared
117 industria textila 2016, vol. 67, nr. 2 ˘CIE L*a*b* COLOR VALUES OF FABRICS DYED
WITH WALNUT BARK
Pepsin Trypsin
60 min 60 min
0% 1% 3% 5% 0% 1% 3% 5%
L*36.89 36.53 36.33 37.73 L*36.19 36.15 35.83 34.93
a* 8.65 8.56 8.61 8.72 a* 8.24 8.28 8.22 8.07
b*18.07 17.61 17.87 18.33 b*16.85 17.14 16.79 16.53
C*20.03 19.58 19.84 20.3 C*18.76 19.03 18.7 18.4
ho64.44 64.08 64.28 64.56 ho63.95 64.24 63.91 63.99
DE 0.00 0.59 0.60 0.88 DE 0.00 0.30 0.37 1.31
120 min 120 min
0% 1% 3% 5% 0% 1% 3% 5%
L*36.95 36.48 36.83 36.76 L*36.18 36.32 35.99 34.38
a* 8.86 8.78 8.72 8.57 a* 8.29 8.32 8.26 8.14
b*18.33 18.19 18.2 17.72 b*16.89 17.01 16.98 16.54
C*20.36 20.2 20.19 19.68 C*18.82 18.94 18.89 18.43
ho64.21 64.24 64.4 64.19 ho63.87 63.92 64.06 63.8
DE 0.00 0.50 0.23 0.70 DE 0.00 0.19 0.21 1.84Table 2PICTURES OF THE FABRICS DYED WITH WALNUT BARKS
Pepsin Trypsin
0% 1% 3% 5% 0% 1% 3% 5%60 min 120 minTable 1
Fig. 4. Relative color strength (K/S%) of the fabrics dyed
with walnut barks

with their blank process. In particular, in the process
that used 5% trypsin, the color efficiencies usedincreased nearly 10% compared to their blank pro-cess. For example if the fabric was modified with 5%trypsin for 120 min., the color efficiency was 11.6 %higher than that of the fabric dyed after the treatmentwith 0% trypsin for 120 minutes.The other important parameter in the coloration oftextile materials is the fastness properties of the col-ored fabrics. For this reason the fabrics colored withwalnut barks were tested in terms of washing andlight fastnesses.The fastnesses of the fabrics dyed with walnut barksshowed the usability of walnut barks in the colorationof polyamide samples. Dyeing with walnut barksexhibited excellent washing fastnesses but limitedlight fastnesses. Meanwhile, it was observed that theenzymatic processes prior to dyeing did not causeany change in the fastnesses of the fabrics.
•Dyeing with pomegranate peels
Pomegranate peels were also investigated for thecoloration of the polyamide samples. It was observedthat coloration of the polyamide samples could beachieved with the use of pomegranate peels. Whenusing pomegranate peels slightly desaturated orangecolors and yellow shades were obtained (table 4).In addition to the dyeability of pomegranate peels,the effect of enzymes on the obtained colors was alsotested by the use of CIE L*a*b* values. It was observed that, depending on the enzymaticapplication, some differences according to the blankprocessed fabrics can occur. With the use of pepsinenzyme it was observed that the highest color differ-ence (Delta E) according to the blank processed fab-ric was found to be 1.38. This difference wasobserved between the fabrics modified for 120 min-utes with 0% pepsin enzyme and those modified for120 minutes with 3% pepsin enzyme. On the otherhand, with the use of trypsin enzyme the obtainedcolors were generally redder and the yellow shadewas slightly reduced (table 5). As a result, the colordifferences (Delta E) according to the blank process-es become dominant. For example, the fabrics mod-ified with 5% trypsin for 60 and 120 minutes present-ed a 3.93 and 3.35 color difference according to theirblank processed fabrics respectively.The other important parameter for the evaluation ofthe colors was the color efficiencies after dyeing. Itwas found that pepsin based enzymatic modificationdid not cause a significant positive effect when theblank process for each enzymatic process was takeninto account. In fact, in some cases, the use of pepsinenzyme also caused a reduction in color efficiencies.Likewise, the use of trypsin enzyme did not cause asignificant improvement in the color efficiencies of the
118 industria textila 2016, vol. 67, nr. 2 ˘PICTURES OF THE FABRICS DYED WITH POMEGRANATE PEELS
Pepsin Trypsin
0% 1% 3% 5% 0% 1% 3% 5%60 min 120 min
Table 4FASTNESSES OF THE FABRICS DYED
WITH WALNUT BARKS
Washing fastness Light
fastness Sta. Alt.Pepsin
60 min0% 5 5 2/3
1% 5 5 2/3
3% 5 5 2/3
5% 5 5 2/3120 min0% 5 5 2/3
1% 5 5 2/3
3% 5 5 2/3
5% 5 5 2/3Trypsin
60 min0% 5 4/5 2/3
1% 5 4/5 2/33% 5 4/5 2/35% 5 4/5 2/3120 min0% 5 5 2/3
1% 5 5 2/3
3% 5 5 2/3
5% 5 5 2/3Table 3
Fig. 5. Relative color strength (K/S%) of the fabrics dyed
with pomegranate peels

fabrics. None of the process conditions ensured a 5%
or higher improvement in color efficiencies accordingto the blank processes.The fastnesses of the fabrics dyed with pomegranatepeels were also tested and are shown in table 6. Asin the dyeing with walnut barks, after dyeing withpomegranate peels the washing fastnesses of thefabrics were found to be excellent. No significanteffect due to the enzymatic process was observed.On the other hand, the light fastnesses of the sam-ples were found to be worse and, as in washing fast-nesses, the enzymatic processes did not have anyeffect on the light fastnesses.
CONCLUSION
Man made fibers have become increasingly popular.
This increase in the popularity of these fibers is ofcourse related with the increase in population of theworld. These fibers are generally clean, so no
det
ailed pretreatment is necessary; however some
modification prior to use can be applied for theimprovement of their dyeability, comfort and function-ality. There are a lot of studies on this issue. Thisstudy focused on the modification of polyamide fibersand their dyeability with natural dye sources. There are studies on the modification of thepolyamide with enzymes but information about dye-ing after this modification with natural dyes is inade-quate. Two different natural dye sources were select-ed because of widespread cultivation of them in
Turkey. Walnut barks are typically alphanaphtho-quinones based and can be considered as dispersedyes [10]. The dyeing principle in extracts from greenwalnut shells is 5-hydroxy-1,4-naphthoquinone [18].The other tested natural dye source was thepomegranate peels which can be considered as akind of direct dyes [10]. The major coloring compo-nent is tannin and ellagic acid [12]. It was observedthat the selected natural dye sources could be usedfor the coloration of polyamide samples with low lightfastnesses. Therefore in future studies, it will be inter-esting to determine if alternative natural dye sourcescan ensure higher light fastnesses. Moreover it wasobserved that protease enzymes can be used for themodification of polyamide fibers but this modificationdid not generally or significantly increase the dyeabil-ity of the polyamide samples with the selected natu-ral dye sources because of their dyeing mechanism.So for the environmentally finishing of polyamide fab-rics different natural dyes which behave like aciddyes can also be tested. Finally, it is hoped that thefindings reported in the paper will be useful for theevaluation of alternative enzymatic processes andnatural dyes in future studies.
ACKNOWLEDGMENT
This work was supported by the Research Fund of Erciyes
University . Project Number: FBA-1
1-3777.
119 industria textila 2016, vol. 67, nr. 2 ˘BIBLIOGRAPHY
[1] Cook, J. G., Handbook of T extile Fibres: II. Man-Made Fibres, Merrow Publishing Co. Lt d., 5th edn. repr., Durham
England, 1993, pp. 194, 221–223.FASTNESSES OF THE FABRICS DYED
WITH POMEGRANATE PEELS
Washing fastness Light
fastness Sta. Alt.Pepsin
60 min0 % 552
1 % 5523 % 5525 % 552120 min0 % 5521 % 5523 % 5525 % 552Trypsin
60 min0% 4/5 5 21% 4/5 5 23% 4/5 5 25% 4/5 5 2120 min0 % 5521 % 5523 % 5525 % 552Table 6
CIE L*a*b* COLOR VALUES OF FABRICS DYED
WITH POMEGRANATE PEELS
Pepsin Trypsin
60 min 60 min
0% 1% 3% 5% 0% 1% 3% 5%
L*67.00 67.07 67.11 67.69 L*69.03 68.91 67.02 65.65
a* 2.10 2.01 2.03 1.93 a* 0.68 0.62 1.43 2.29
b*26.77 26.69 26.90 27.33 b*30.86 30.86 29.48 29.66
C*26.85 26.77 26.97 27.39 C*30.87 30.86 29.51 29.75
ho85.53 85.70 85.69 85.96 ho88.75 88.85 87.22 85.60
DE 0.00 0.14 0.18 0.90 DE 0.00 0.13 2.55 3.93
120 min 120 min
0% 1% 3% 5% 0% 1% 3% 5%
L*68.60 68.06 67.56 68.67 L*68.24 68.42 66.24 65.54
a* 1.44 1.63 1.59 1.26 a* 0.96 0.90 1.89 2.40
b*27.86 27.42 26.96 27.27 b*30.44 30.16 28.56 29.08
C*27.90 27.47 27.01 27.29 C*30.46 30.17 28.62 29.18
ho87.04 86.60 86.62 87.36 ho88.20 88.29 86.22 85.30
DE 0.00 0.72 1.38 0.62 DE 0.00 0.34 2.90 3.35Table 5

120 industria textila 2016, vol. 67, nr. 2 ˘Authors:
M. İbrahim Bahtiyari1
Hüseyin Benli2
1Erciyes University Textile Engineering Department, Kayseri, Turkey
2Erciyes University Mustafa Çıkrıkçıoğlu Vocational School, Kayseri, Turkey
e-mail: bahtiyari@erciyes.edu.tr, hbenli@erciyes.edu.tr
Corresponding author:
M. İbrahim Bahtiyari
bahtiyari@erciyes.edu.tr[2] El-Ola, S. M. A, Moharam, M. E., Eladwi, M. M., El-Bendary, M. A., Optimum conditions for polyamide fabric modi-
fication by protease enzyme produced by Bacillus sp . In: Indian Journal of Fibre & Textile Research, 2014, vol. 39,
no. 1, pp. 65–71.
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Francis Group, Boca Raton, USA, 2007, pp. 124–125.
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Edited by P.J. Hauser, InTech, Croatia. 2011, p. 33.
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protease activity towards polyamide substrates . In: Enzyme and Microbial Technology, 2007, vol. 40, no. 1,
pp. 1678–1685.
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nase activity towards polyethylene terephthalate and polyamide 6,6 fibers . In: Journal of Biotechnology, 2007,
vol. 128, no. 4, pp. 849–857.
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pp. 798–814.
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Kumbasar, InTech, Croatia, 2011, pp. 29–56 (ISBN 978-953-307-783-3).
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Nahrung/Food, 2003, vol. 47, no. 1, pp. 28–32.
[14] Bechtold, T., Natural Colorants – Quinoid, Naphthoquinoid and Anthraquinoid Dyes . In: Hand Book of Natural
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INTRODUCTION
Self-cleaning fabrics have gained extensive attention
for it
s unique properties, having great potential on the
hygienic, self-disinfecting and contamination freeapplications. In the textile field, two approaches couldbe used to produce self-cleaning surface, namely:hydrophobic and hydrophilic. The former approach isinspired by the Lotus effect, which mimics themicrostructure of the surface of lotus leaf to get superhydrophobic surface. The later approach takesadvantage of the photocatalytic effect, using pho-toactive materials such as titanium dioxide (TiO
2) to
induce oxidation reactions on the surface, whichcould decompose organic dirt or contaminantsattached on the surface [1]. However, the processused to produce hydrophobic surface has its draw-backs because the fluorocarbons used are harmful tothe environment and human beings. Besides, theself-cleaning function disappears gradually over thenumber of laundering cycles and also the time [1].Compared with the hydrophobic method, the
hydrophilic approach provides a good alternative, aswell as the self-cleaning function, it also imparts thetextile surface with deodorizing, antimicrobial and UVprotection functions.Over the past few decades, the nano-sized TiO
2has
been widely investigated and used in the textile fieldas photocatalyst for self-cleaning applications [2, 3].The mechanism of photoreaction induced by TiO
2
lies in: when TiO2surface is irradiated by the ultravi-
olet light (UV), with energy equal or higher than itsband gap (> 3.0 eV), electrons on the surface will beexcited and escaped from the valence band to theconduction band, resulting in the formation of nega-tively charged electrons in the conduction band aswell as the positively charged holes in the valenceband. The electron-hole pairs on the surface willreact with the oxygen or water to form highly activeoxygen species. The organic compounds will be final-ly oxidized by the active species to carbon dioxidePreparation and evaluation of the self-cleaning poly (lactic acid) (PLA) film
blended with Titanium dioxide (TiO2) nano particles
CHENGJIAO ZHANG XIN CAI FAMING WANG
REZUMAT – ABSTRACT
Prepararea și evaluarea peliculelor de acid poli (lactic) (PLA) cu funcție de autocurățare în amestec
cu
nanoparticule de dioxid de titan (TiO2)
În această lucrare, un material fotocatalitic (nano dioxid de titan) a fost introdus în acid poli (lactic) (PLA) pentru a
produce pelicule cu funcție de autocurățare. Prototipurile conținând 0, 5, 10, 15 și 20 wt% nanomateriale au fostpregătite și corodate cu proteinază K pentru a depune nanoparticulele pe suprafață. Proprietățile termice ale matriceipolimerice au fost evaluate prin calorimetrie cu scanare diferențială (DSC) și analiza termogravimetrică (TGA). Funcțiade autocurățare a fost evaluată prin decolorarea albastrului de metilen (MB) în stare apoasă, prin intermediul unuispectrofotometru UV-VIS. S-a constatat că nanoparticulele au avut un efect minim asupra proprietății termice a matriciipolimerice. Probele cu conținut de 15 wt% nanomaterial ar putea degrada în totalitate albastrul de metilen după iradiereacu UV timp de 24 de ore. Cercetările ar putea furniza recomandări utile în ceea ce privește dezvoltarea de textile cufuncție de autocurățare pe bază de nanoparticule de TiO
2.
Cuvinte-cheie: dioxid de titan (P25), acid poli (lactic) (PLA), suprafață cu funcție de autocurățare, fotocatalitic, corodareenzimatică, fotodegradarea albastrului de metilen
Preparation and evaluation of the self-cleaning poly (lactic acid) (PLA) film blended with
Titanium dioxide (TiO
2) nano particles
In this study, a photocatalytic material (the nano-sized titanium dioxide) was introduced into poly (lactic acid) (PLA) toproduce films with self-cleaning function. Prototypes containing 0, 5, 10, 15 and 20 wt% nano filler were prepared andthen etched with proteinase K to expose the nano particles on the surface. Thermal properties of the polymer matrixwere evaluated by the differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). Theself-cleaning function was assessed by the discoloration of methylene blue (MB) in aqueous condition via a UV-visspectrophotometer. It was found that the nano particle had a minimal effect on the thermal property of the polymermatrix. The samples containing 15 wt% nano filler could totally degrade the methylene blue after 24h UV irradiation. Theresearch findings might provide useful suggestions on the development of self-cleaning textiles based on TiO
2 nano
particles.
Keywords : Titanium dioxide (P25), poly (lactic acid) (PLA), self-cleaning surface, photocatalytic, enzymatic etching,
methylene blue photo-degradation
121 industria textila 2016, vol. 67, nr. 2 ˘

and water [3, 4].The sol-gel method is one of the
most common methods to apply nano-sized TiO2par-
ticles onto textile substances, with the typical dip-pad-dry-cure process [5]. However, textile sub-stances produced by this method tend to delaminatebecause of the relatively weak adhesion between thenano particles and its support fabrics, which limits thedurability of the self-cleaning function [6]. In additionto functional coating, intrinsic self-cleaning textilesubstances could be produced by adding nano TiO
2
particles into the polymer matrix during the meltblending process [7]. Cho found that PET yarns con-taining low TiO
2concentrations (no more than 1100
ppm) had no significant effects on the mechanicalproperties compared with that of the pure PET yarn[8]. By incorporating the nano-sized photocatalyticTiO
2into textiles, it is possible to engineer textiles
with a multifunctional antibacterial and self-cleaningsurface [9]. In textile fields, both commercially avail-able titanium dioxide nano powder (i.e., DegussaP25) and titanium dioxide particles synthesized froma precursor via the sol-gel method were applied tomaterials such as cellulose , cotton , wool , and syn-thesized materials [10, 11, 12, 13–15]. The poly (lac-tic acid) (PLA) is a low cost biodegradable materialand the PLA fibres have good mechanical properties.The unique properties of PLA make it to have greatpotential to replace conventional fibres synthesizedfrom the fossil fuel [16]. However, the PLA is a newemerged material and few studies have investigatedthe functional performance of the PLA fibre or filmblended with the nano-sized TiO
2.
In this study, films with self-cleaning function wereprepared by PLA with different concentration of TiO
2
via melt blending method. Enzymatic surface erosionwas introduced to remove surface of the PLA poly-mer to expose nano filler to the environment. Theeffects of concentration of nano filler and the enzy-matic surface erosion on the thermal properties of thefilms were investigated. The self-cleaning functionwas evaluated by the decolouration of Methyleneblue in aqueous conditions.
METHODOLOGY
Materials
The PLA Polymer 6201D (NatureWorks, Blair, NE;
melt flow index: 10–30 g/10min);
P25 (the nano-sized
Titanium (IV) oxide) (ALDEICH SIGMA, St. Louis,MO; diameter: 21 nm; surface area: 35–65 m
2/g);
Proteinase K (P2308, SIGMA ALDEICH, St. Louis,MO) was applied to the enzymatic etching process,the protein content is > 90% and its specific activity is> 30 units/mg. In addition, the 30 mM Tris-HCl bufferwas prepared by the following method: 3.634 g (i.e.,0.03 mol) Trizma base (Sigma) was first dissolved inthe 800 ml MilliQ water, the pH value was adjusted to
8.6 with HCl, and finally 1 L MilliQ water was added.
Preparation of films
Five film batches, with contents of 0, 5, 10, 15, and
20wt% nano filler were prep
ared via a two-step
procedure: 1) preparation of the master batch containing 20 wt%
nanofiller by mechanical mixing the nano powder
with dried PLA pellet;2) extrusion blending of the master batch and thepure PLA pellet according to the target nanofiller con-centration and then extrusion with a 0.4 mm film spin-neret.The master batch was produced by Coperion com-pounder (ZSK 26K, Stuttgart, Germany), and thefeeding of the PLA pellet and the nano filler was per-formed. The screw speed was 230 r/min. Beforecompounding, the titanium dioxide was dried at100°C for 12 h and the PLA was dried at 80 °C for
12
h. After compounding, the master batch was
cooled by water and chopped into granule by Scheer(Reduction Engineering GmbH, Korntal-Muenchingen,Germany).The films were produced by a Micro 15 cc TwinScrew Compounder (DSM Research Netherlands)with a 0.4 mm film spinneret. Prior to production, themaster batch and the pure PLA pellet were dried in avacuum oven (MMM Einrichtungen GmbH, Planegg,Germany) at 80°C for 12 h. The screw speed was100 r/min, the compounding temperature was con-trolled by three temperature zones on the com-pounder. The feeding temperature was 190°C, andthe mixing temperature was 230°C. After the extru-sion, the thickness of the obtained films was withinthe range of 100–400 µm. The films were named asPure PLA, 5% TiO
2, 10% TiO2, 15% TiO2and 20%
TiO2respectively, according to the nano filler con-
centration.
Enzymatic surface erosion
During the enzymatic etching process, all experi-
ment
s followed the method described by MacDonald
et al. [17]. Four pieces of films, of the same batch(size: 1 cm × 3 cm) were placed in the conical flask
containing 5 ml of the 30 mM Tris-HCl buffer, 1 mgproteinase K and 1 mg sodium azide. The flask wascovered with a cotton ball and was put in water bath.The temperature of the water bath was maintained at37°C and the flasks were shaken slowly at 80 r/min.throughout the whole incubating process. Before andafter the incubation, samples were dried at an ambi-ent temperature of 20°C. Different incubating timeperiods of 2, 4 and 6 h were introduced. The weightloss of per unit surface area was calculated accord-ing to eq. 1. Because the thickness of the film wasbetween 100–400 µm, the surface area contributedby the thickness on the total surface area was mini-mal and thus could be neglected.
W
b– WaWloss (mg/μm2) = (1)
Sbefore
where, Wbis the mean weight before erosion; Wa–
the mean weight after erosion; Sbefore– the surface
area before erosion.
Differential scanning calorimeter (DSC)
The DSC analysis was performed with a DSC Q1000
instrument (T
A Instruments, New Castle, USA).
Samples were heated to 200°C twice at a heating
122 industria textila 2016, vol. 67, nr. 2 ˘

rate of 10°C/min. In order to eliminate the previous
heat history, the sample was held isothermally at200°C for 2 min after the first heating process, andthen was cooled down to –10°C at a cooling rate of10°C/min before the second heating cycle. The cool-ing and second heating processes were used to eval-uate the thermal property of the sample.
Thermogravimetric analysis (TGA)
The TGA experiments were performed with a TGA
Q500 instrument (T
A Instruments, New Castle, USA).
Sample was heated to 600°C at a heating rate of10°C/min, and was held at 600°C for 2 min. The plat-inum plate was cleaned by the alcohol burner beforeeach test.
Degradation of methylene blue (MB)
The photocatalytic behaviour of the prototypes was
determined by the decolouration of the methyleneblue (MB) (GFS Chemicals,
Powell, OH) in aqueous
condition under the irradiation of two 6 W UV tubes(VL-206SLS) with the predominate wavelength of365 nm. During the test, 2 pieces of films were put ina glass bottle containing 5 ml methylene blue solutionand the bottle was then covered and placed underthe UV tubes. The distance between the testing sam-ple and UV tubes was 20 cm. The initial concentra-tion of the methylene blue was 2 mg/l. The absorptionspectrum was measured before UV irradiation, after3, 7 and 24 h UV irradiation by a UV-Vis spectropho-tometer (LIBRA S60, Cambridge, UK). By measuringchanges in the absorption spectra and theabsorbance at specific wavelengths, the degradationcontent of methylene blue could be calculated. Theabsorption spectra of the methylene blue solutionwithout UV irradiation and the tap water was consid-ered as the reference.
RESULTS AND DISCUSSION
Enzymatic surface erosion
The surface area of each sample film is 600 mm
2.
The non-normalized mean weight loss after enzy-
matic surface erosion is displayed in table 1. Theweight loss is caused by the hydrolysed PLA andreleased TiO
2 particles. After the 2 h enzymatic etch-
ing, the pure PLA showed the greatest per unit weightloss of 2.83 μg/mm
2, which is almost 1.8 μg/mm2
higher than that of the 5% TiO2. The per unit weight
loss of 10% TiO2, 15% TiO2and 20% TiO2was 1.75
μg/mm2, 1.08 μg/mm2and 2.13 μg/mm2, respectively. For those samples with 4 h enzymatic treatments, it
was observed that the TiO2-containing samples,
compared with the pure PLA, had a more significantincrease in the per unit weight loss. The 5% TiO
2, for
example, lost 7.79 μg/mm2after 4 h surface erosion.
If it is assumed that the 5% TiO2had the same weight
loss during the first 2 h with that of the group had 2 htreatment, then, it had lost around 6.75 μg/mm
2
during the second 2 h. Similar trends were also foundin other TiO
2-containing samples. This interesting
finding might be attributed to the increase in activa-tion of proteinase K or the deviation of pH which facil-itated the PLA hydrolysis process. Another possibilitywas that for the TiO
2-containing samples, compared
with the pure PLA, more enzyme molecules could beattached onto the PLA per unit area, and thus a high-er etching speed was triggered. Besides, the releaseof nano TiO
2may also contributed to the difference in
weight loss.After the 6 h treatment, the 20% TiO
2lost more
weight than the other samples, i.e., 9.79 μg/mm2. It
should be noticed that for TiO2-containing samples,
the weight loss after the 6 h treatment was almostequal to the sum of weight loss of samples after the2 and 4 h treatments. For the pure PLA samples, theweight lost 8.13 μg/mm
2after the 6 h treatment,
which was approximately 1 μg/mm2smaller than that
of TiO2-containing samples. This finding was in line
with the study of Fukuda and Tsuji [18], who alsofound the composite film of PLA/TiO
2had a higher
weight loss, compared to pure PLA, when treatedwith enzyme. This difference in weight loss might bedue to the hydrophilic TiO
2particle permitting facile
permeation of the enzyme into interfaces, resulting inthe enzymatic hydrolysis at interfaces as well as onthe film surface. Such enzymatic hydrolysis at PLAand additive material interfaces has also been report-ed by other researcher [19].
Thermal properties
The typical DSC heating scans presented in figure 1,  a
showed
that the nano titanium dioxide filler had limit-
ed effect on the thermal behaviour of the polymer
matrix. For all samples, the introduction of the titani-um dioxide did not affect the glass transition temper-ature (i.e., T
g = 62 °C), and the melting temperature
(Tm = 165 °C). This indicated that the nano particles
do not affect the mobility of the bulk polymer macro-molecular chain. The introduction of TiO
2in PLA did
not result in noticeable change in Tgand Tmwas also
reported by Luo et al. [20]. However, nano particlesaffected the cold crystallization temperature.
123 industria textila 2016, vol. 67, nr. 2 ˘MEAN WEIGHT LOSS AFTER THE ENZYMATIC TREATMENT
SampleProcessing time
(h)Pure PLA 5% TiO210% TiO215% TiO220% TiO2
Per unit area
weight loss
(μg/mm2)2 2.83 1.04 1.75 1.08 2.13
4 3.13 7.79 8.21 8.17 8.67
6 8.13 9.25 9.54 9.04 9.79Table 1

Generally, compared to the pure PLA, the addition of
TiO2in PLA led to a lower cold crystallization tem-
perature, and the higher the TiO2filler, the lower the
cold crystallization with the exception of 20% TiO2.
This was contrary to the finding of Luo et al. [20], whofound no evident change in cold crystallization tem-perature of PLA matrix when the content of TiO
2was
8 wt%. This difference might be caused by the varia-tion in TiO
2 content.
Figure 1,  bpresents the typical effect of enzymatic
treatment on the thermal property of the PLA con-taining 10% TiO
2. The enzymatic surface erosion had
no significant impact on Tgand Tm. This was mainly
because the enzymatic surface erosion only occurredon the surface and it had minor effect on the bulkproperty. However, enzymatic surface erosion affect-ed the cold crystallization temperature, whichdecreased from 110°C to around 100°C. For all sam-ples, it seemed that the processing time affected thecold crystallization temperature randomly.Figure 2,  ashows the thermal degradation of different
samples in the TGA analysis. Generally, the introduc-tion of the nano filler increased the thermal degrada-tion temperature. The pure PLA started to degrade atabout 300°C, approximately 20°C lower than that ofthe TiO
2-containing samples. It was evident that the
added nano particles, instead of accelerating the
thermal degradation of the PLA, made the polymermore thermal stabilized. The post-experiment weightpercentage of the degraded samples was close to 0,5, 10, 15 and 20%, which were the remaining TiO
2
particles.Figure 2,  bshows the effect of enzymatic treatment
on the thermal degradation behaviour. Comparedwith samples without the enzymatic treatment, theenzymatic treated samples tended to degrade at alower temperature. This might due to the degradationof the surface PLA during the enzymatic treatment.
Discoloration of methylene blue (MB)
In order to guarantee the maximum photocatalytic
activity
, samples with the maximum amount of the
nano filler exposed onto the film surface (i.e., sam-ples with greatest per unit area weight loss in eachbatch), were used to assess the degradation perfor-mance of methylene blue (MB). In order to examinewhether the surface erosion was essential to makethe film photocatalytic, the 20% TiO
2without enzy-
matic treatment was used as a reference.
124 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 1. DSC curves of different prototypes:
a– prototypes without enzymatic treatment; b – samples with 10% TiO2 before and after enzymatic treatmenta b
Fig. 2. TGA curves of different prototypes:
a– samples without the enzymatic treatment; b– the pure PLA before and after the enzymatic treatmenta b

Figure 3 shows the typical tendency in absorbance
peak shift of the surface treated samples. With theincreasing UV irradiation time, the absorption curvesshifted towards to that of the water. After the 24 h irra-diation, the absorbance curves were close to or over-lapped with that of the water, which indicated the MBhad almost or totally degraded. It was also found thatfor the 20% TiO
2without enzymatic treatment, there
was no change in the absorption spectra curve after24 h UV irradiation, which indicated no photo-degra-dation of the methylene blue occurred. Hence it couldbe concluded that the enzymatic surface erosion wasessential to make the sample photocatalytic.During the experiment, it was found that all samplesdisplayed significantly absorption changes at a wave-length of about 664 nm. Hence, the methylene bluesolution had the maximum absorption at this wave-length. This was in good agreement with previousstudies [21, 22]. Therefore, such a wavelength maybe used as a sign to judge the MB concentrationlevel. By measuring the absorbance changes at664nm after UV irradiation and comparing that withthe value of water, it is possible to quantitatively eval-uate the degradation ratio of the methylene blue. Itcan be seen from table 2 that all samples had adegradation of over 84% MB after the 24 h UV irradi-ation. Among all samples, the 15% TiO
2showed the
same absorbance with that of the water, i.e., themethylene blue has totally degraded during the 24 hperiod, followed by the 10% TiO
2with 98% methy-
lene blue degradation. For the 20% TiO2, the
decrease in the discoloration performance may be an
indication of unevenly dispersion of the nano filler inthe polymer matrix. The registered decrement mayalso due to the aggregation of the inorganic nanofiller occurred at such a high percentage of TiO
2par-
ticles.
CONCLUSIONS
This study has demonstrated that it was possible to
produce the photocat
alytic film based on the nano-
sized titanium dioxide and the poly (lactic acid) (PLA)via blending method. The enzymatic surface erosionwas essential to make the product photocatalytic,and the proteinase K was capable of removing thesurface PLA to expose the nano filler. The introduc-tion of the nano filler and surface erosion processhad minor effect on the thermal behaviour of the poly-mer matrix. All samples showed more than 84%degradation of MB after 24 h UV irradiation, and thefilm containing 15 wt% nano filler proved propertiesof oxygen and argon RF plasma-activated polyesterfabrics loaded with TiO
2nanoparticles. However, the
dispersion of the nano filler in the polymer matrix wasnot addressed in this study. It is necessary to investi-gate this in further studies to find the most suitableapproach to combine textile substances with nanoTiO
2 particles.
125 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 3. The absorbance character in MB solution:
a – the 5% TiO2samples after 6 h enzymatic treatment; b – the 10%TiO2samples after 6 h enzymatic treatmenta b
CHANGES IN THE ABSORBANCE OF SAMPLES AFTER 0, 3, 7 AND 24 H UV IRRADIATION
Irradiation time (h) 5%TiO210%TiO215%TiO220%TiO2water
0 0000
–0.3373 –0.079 –0.130 –0.185 –0.110
7 –0.133 –0.233 –0.264 –0.266
24 –0.282 –0.331 –0.337 –0.305
Degradation ratio of MB after 24 h
irradiation (%)83.7 98.2 100.0 90.5 100.0Table 2

Acknowledgements
The authors would like to express their appreciation for the
support from the Swedish School of
Textiles, University of
Borås and the work was financially supported by ‘The OpenFoundation of Key Laboratory of Advanced Textile
Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education’ (Project No:2014002).
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Authors:
CHENGJIAO ZHANG1, 2
XIN CAI3
FAMING WANG1
1 Laboratory for Clothing Physiology and Ergonomics (LCPE), the National Engineering Laboratory for Modern Silk,
Soochow University, Suzhou 215123, China
2 The Swedish School of Textiles, University of Borås, Borås 50190, Sweden
3 Key laboratory of Advanced Textile Material and Manufacturing Technology of Ministry of Education, College of
Materials and Textiles, Zhejiang Sci-Tech University, Hangzhou 30018, China
e-mail: chengjiaozhang@gmail.com, 507054163@qq.com, dr.famingwang@gmail.com
Corresponding author:
F
AMING WANG
dr.famingwang@gmail.com

INTRODUCTION
Textile structural composites have been used in vari-
ous industrial, ballistic and medical areas due to theirhigh stif
fness to weight ratio, delamination free and
damage tolerance properties [1]. Stitching in layeredtwo dimensional (2D) woven preform improved thetensile and flexural properties of the compositethrough the distribution of the stress among the lay-ers by stitching yarn [2]. It was reported that stitchingfiber base composites in the out-of-plane directionenhanced the Mode-I and Mode-II interlaminar frac-ture toughness which was experimentally determinedby using double cantilever beam and an end notchedflexure test, respectively [3–6]. The delaminationcrack propagation was suppressed when the 2Dstitched woven composites were under repeatedimpact loading at an energy level close to the delam-ination threshold. It was also claimed that high lineardensity stitching yarns offered a better delaminationresistance [7]. Another study showed that threedimensional (3D) orthogonal woven composite hadthe greatest resistance to penetration under low
velocity impact and dissipated more total energy than2D plain woven composites. This is due to the Z-fiberin the structure [8]. Absorbed energy for the densestitch spacing composite was high compared to theloose stitch spacing composite and the dense stitchcomposite showed less damage size compared tothe loose stitch composite [9–11]. The mechanical properties of carbon fiber/phenolicmulti-walled carbon nanotube (MWCNT) compositesare better compared to carbon fiber/phenolic com-posites [12]. In addition, it was reported that the car-bon nanotubes enhanced the interface properties ofcomposite structure through a toughening effect,fiber-bridging mechanism and the direct reinforce-ment of the matrix [13, 14]. Carbon nanotubes (CNT)-modified composites had an increase in glass transi-tion temperature, coefficient of thermal expansionand fracture toughness due to the modification of theinterfacial properties and the increased matrix rigidity[15, 16]. It was reported that grafting of CNT ontoa carbon fiber surface caused a three dimensionalREZUMAT – ABSTRACT
Proprietățile de rezistență la forfecare interlaminară a nanocompozitelor cu cusături multiple
Au fost studiate proprietățile de rezistență la forfecare interlaminară în direcția urzelii și bătăturii ale nanocompozitelor
țesute bidimensionale din E-glass/poliester multistratificate cu cusături multiple. Când conținutul de nanomaterial dindioxid de siliciu din structura compozitului fără cusătură E-glass/poliester crește, forțele de forfecare interlaminarădirecționale specifice ale nanostructurilor fără cusătură cresc. Pe de altă p
arte, forțele de forfecare interlaminară
direcționale specifice ale structurilor fără cusătură au fost mai mici decât cele ale nanostructurilor cu cusături multiple.Toate structurile compozite au înregistrat o scădere a forței de forfecare interlaminară între straturi, în secțiuniletransversale. Dar, scăderea forței de forfecare interlaminară în nanostructurile cu cusături multiple nu s-a propagat înzone mai mari. Direcția de coasere, densitatea de coasere, firul de cusut, tipul de cusătură și cantitatea de nano –
materiale din structurile compozite au fost identificate ca parametri importanți.
Cuvinte-cheie: țesătură preformată cu multiple cusături, rezistență la forfecare interlaminară urzeală-bătătură,
insuficiența forței de forfecare interlaminară, nanocompozit, delaminare
Interlaminar shear strength properties of multistitched preform nano composites
Warp and weft directional interlaminar shear strength properties of the developed two dimensional multistitched
multilayer E-glass/polyester woven nano composites were studied. When the nano silica material in the unstitchedE-glass/polyester composite structure increased, the directional specific interlaminar shear strengths of theunstitched/nano structures increased. On the other hand, the directional specific interlaminar shear strengths ofunstitched structures were lower than those of the multistitched/nano structures. All composite structures hadinterlaminar shear failure between layers in their cross-sections. But, the interlaminar shear failure in multistitched andmultistitched/nano structures did not propagate to the large areas. The stitching direction, stitching density, stitchingyarn, stitching type and the amount of nano materials in the composite structures were identified as importantparameters.
Keywords: m ultistitched woven preform, warp-weft interlaminar shear strength, interlaminar shear failure, nano composite,
delamination
127 industria textila 2016, vol. 67, nr. 2 ˘Interlaminar shear strength properties of multistitched preform
nano composites
KADIR BILISIK HUSEYIN OZDEMIR GAYE YOLACAN KAYA

128 industria textila 2016, vol. 67, nr. 2 ˘network around the carbon fibers [17, 18]. The fiber
was coated using the CNTS in order to enhance thefiber/matrix interfacial properties. It was claimed thatCNTS coated fiber/matrix composite showed the bet-ter interfacial shear strength due to tougher andstiffer interfacial regions [19, 20]. Another study wasalso claimed that 2D woven composite aligned withCNTs to the out-of-plane direction provided improve-ments on Mode-I interlaminar fracture toughness dueto the pull-out of nanotubes which was occurredbetween fiber and epoxy via bridging [21–23]. It was reported that the silane functionalizedMWCNTs in the composites generally enhances theirmechanical, thermal and electrical conductivity prop-erties compared to the untreated CNTs composites[24–28]. Another study showed that the flexural andfracture properties of basalt fiber/epoxy silane-treat-ed CNTs composites were improved partly due to thedecreased agglomeration and partly interfacial bond-ing between the CNTs and epoxy resin, and support-ed the homogeneous load transfer capacity of basaltfibers [29, 30]. It was also stated that the fluorinefunctionalized carbon nanotubes (f-CNTs) in the fiberreinforced epoxy composite increased the interlami-nar shear fracture toughness [31]. Recently, it was shown that the interlaminar shearfailure in multistitched and multistitched/nano struc-tures did not propagate to the large areas. The spe-cific interlaminar shear strengths of the unstitched/
nano structures increased by increasing the nano sil-ica material [32, 33]. As seen in literature, there is alittle study on stitched and nano composite struc-tures. Therefore, the objective of this study was toexperimentally understand the interlaminar shearstrength properties of the developed 2D multistitchedE-glass/polyester nano structures.
EXPERIMENTAL PART
2D unstitched and multistitched woven
E-glass/polyester preform and composite
E-glass woven fabric (Cam Elyaf A.S., Turkey) was
used to make unstitched and multistitched multilayerwoven structures.
The fiber (Cam Elyaf Inc., TR),
matrix (Crystic 703PA, Scott Bader, UK) and nanomaterial (nano sphere, Sigma-Aldrich, Germany)specifications are presented in table 1. Fabric speci-fications are presented in table 2. Four types ofE-glass preform structures were mainly developed:unstitched (U1-U3), unstitched/nano (N1-N4), multi-stitched (M1-M12) and multistitched/nano (NM).Figure 1 shows the schematic top views of one direc-tional stitching (a1), two directional stitching (a2), fourdirectional stitching (a3), and schematic cross sec-tional views of multistitching at 0°–90°, ±45° direc-tions (a4, a5). Figure 2 shows actual multistitchedwoven E-glass/polyester nano composite structures.
SPECIFICATIONS OF FIBER, MATRIX AND NANO USED FOR MAKING COMPOSITE
E-glass
fiberPolyester
ResinNano Silica
(SiO2)Nano Carbon
(C)
Fiber diameter (μ) 17 –
Density (g/cm3) 2.56 1.20 2.2-2.6 2.1-2.3
Tensile strength (GPa) 3.5 0.05 0.11 0.2
Tensile modulus (GPa) 76 2.8 73 1000
Elongation at break (%) 4.8 2.1 – –
Melting point (Cș) 841 – >1600 3550
Measured average particle size (nm) – – 30.80±8.6 40.71±7.4
Molecular weight (g/mol) – – 60.1 12.01
Purity (%) – – 99.5 >99
Surface area (m2/g) – – 140-180 >100Table 1
Fig. 1. Schematic views of stitching directions of E-glass preforms:
(a1) top view of one direction; (a2) top view of two direction; (a3) top view of four direction stitching;
(a4, a5) cross-sectional view of multistitching at 0° and 90°, and at ±45° [32]a1 a2 a3 a4 a5

129 industria textila 2016, vol. 67, nr. 2 ˘The developed unstitched performs included a lay-
ered fabric [(0°/90°)]4 (U1) and oriented layered fab-rics as [0°/90°/±45°/±45°/0°/90°] (U2), and [±45°/0°/90°/0°/90°/±45°] (U3). The developed unstitched pre-forms included a layered fabric [(0°/90°)]4 having2.5% nano silica (N1), 5% nano silica (N2), 7.5%nano silica (N3) and 5% nano carbon (N4). Thedeveloped multistitched preforms were divided intothree subgroups. The first was a layered fabric[(0°/90°)]4 one-directionally lightly Nylon 6.6 (M1),Kevlar 129 (M7) and densely Nylon 6.6 (M4), Kevlar129 (M10) stitched in the warp (0°) direction. Thesecond was a layered fabric [(0°/90°)]4 two-direction-ally lightly Nylon 6.6 (M2), Kevlar 129 (M8) anddensely Nylon 6.6 (M5), Kevlar 129 (M11) stitched inthe warp (0°) and weft (90°) directions. The third wasa layered fabric [(0°/90°)]4 four-directionally lightlyNylon 6.6 (M3), Kevlar 129 (M9) and densely Nylon6.6 (M6), Kevlar 129 (M12) stitched in the warp (0°),weft (90°) and ±bias directions in where these pre-
form structures were called “multistiched structure”.Although, the previosly conducted studies on thesestructures were only one-dimensional stitched or onlytwo-dimensional stitched at 0°/90° or ±45°, the cur-rently developed structure was four-directionalstitched at 0°/90° or ±45° all together. In stitching,lock stitching was used and the stitching density wasvaried at 2 step/cm (light stitching) and 6 step/cm(dense stitching). The distance between the adjacentstitching lines was 1 cm. The stitching yarns werealso varied using fully nylon 6.6 (bobbin and needleyarn) and, Kevlar® 129 (DuPont, USA) as the bobbinstitching yarn and nylon 6.6 as the needle stitchingyarn. The tensile strength and modulus of Kevlar®and Nylon 6.6 were 3400 and 600 MPa; 99 and2.46 GPa, respectively. The breaking elongation ofKevlar® 129 and Nylon 6.6 were 3.3 and 41%,respectively. The yarn linear density of Kevlar® 129and Nylon 6.6 were 110 tex and 44 tex, respectively.The stitching machine was made by BrotherIndustries Ltd. DB2-B736-3TR, Japan. 2D unstitched and multistitched multilayer wovenE-glass/polyester preforms were consolidated to makecomposites by using vacuum assisted resin transfermolding (VaRTM) technique. Dicyclopenta diene
based unsaturated polyester resin (Crystic 703PA,Scott Bader, UK) was used. Methyl ethyl ketone per-oxide (MEKP) was used as hardener, 2% by weightof resin to produce neat E-glass/polyester compos-ites. The polyester resin and hardener were mixedhomogenously and applied to the preforms undervacuum at 20°C. However, catalyst (Cobalt Naftalat-CoNAP) was also used to produce nano compositestructures. Amounts of MEKP and CoNAP by weightof resin and mixing conditions are given in table 3.
Table 2
Table 3SPECIFICATIONS OF E-GLASS WOVEN FABRIC
USED FOR MAKING COMPOSITE
E-glass fabric
(Cam Elyaf Inc., TR)
Weave type Plain
Yarn linear
density (tex)warp 2400
weft 2400
Density (per 10 cm)warp 16
weft 18
Weight (g/m
2) 800
Crimp (%)warp 1.24
weft 1.20
Thickness (mm) 1.01Fig. 2. Multistitched woven E-glass/polyester nano composite structures for short beam test [32]:
(a) unstitched (U1), (b) unstitched/nano (N1, N4); (c) multistitched (M10, M1
1); (d) multistitched/nano (NM)a b c d
MIXING CONDITIONS OF NANO MATERIALS IN POLYESTER RESIN FOR VARTM [32, 33]
Nano materials Amount of
nano
materials
(% wt.)Hardener
(MEKP)
(%)Catalyzer
(CoNAP)
(%)Mixing conditions Gelling time
(min)Mechanical
mixing
(min, rpm)Ultrasonic
mixing
(min, °C)
Silica (SiO2)
(nano sphere)%2.5
%4 %0.32 min.
20.000 rpm5 min.
25°C40 min.
%5 60 min.
%7.5 90 min.
Carbon (C)
(nano sphere)%5 %4 %0.32 min.
20.000 rpm5 min.
25°C40 min

130 industria textila 2016, vol. 67, nr. 2 ˘Nano materials were mixed first by a mechanical stir-
rer (IKA-T25 Digital Ultra Turrax, IKA® Werke GmbH& Co. KG) in which mixing was gradually carried outstarting from 3000 rpm to 20000 rpm, stayed for2 min, then from 20000 rpm to 3000 rpm. Later on,mixing was continued in ultrasonic bath, for 5 min at25°C, to get homogeneous distribution of nano parti-cles in polyester resin. After that, matrix was vacu-umed to get rid of the air bubble, and finally harden-er and catalyst were added. This matrix was appliedto the preforms under vacuum at 20°C. The densityof the composite was determined by ASTM D792-91.The composite volume fraction and void contentwere determined by ASTM D3171-99 and ASTMD2734-91, respectively. Before the short beam test,the stitching area of the composite sample wasexamined by a scanning electron microscope-SEM(LEO 440® model, UK).
Short beam test
The short beam test of the composite structures was
performed on a Shimadzu
AG-XD 50 (Japan) tester
equipped with Trapezium® software based on ASTMD2344-00. The short beam testing speed was 1.0mm/min. The test dimensions were considered as25 (width) × 20 (length) mm. The L/d (support spanlength/thickness) ratio was 4/1. The short beam loadapplied to each sample was the warp (0˚) and weft
(90ș) directions, respectively. The cross section of thestructures was examined by an optical microscope(Olympus SZ61, Japan). Based on this examination,the failure modes under the short beam load for eachstructure were identified.
RESULTS AND DISCUSSION
Density and fiber volume fraction result
s
The density and fiber volume fraction results of 2D
unstitched, unstitiched/nano, multistitched and multi-stitched/nano multilayer E-glass/polyester compos-ites are presented in t
able 4. As seen in table 4, the
density, total fiber volume fraction and the void con-tent results indicated that partly stitching and partlyVaRTM process caused a local misalignment anduneven fiber-matrix-nano placement in the structureas shown in figure 3. The stitching caused a localmisalignment and uneven fiber placement duringneedle piercing to the preform structure. In addition,when the stitching directions in the structureincreased, the stitching yarn volume fraction (Vsfw)increased depending on the stitching density andyarn types. However, the total volume fraction (Vtfw)of the structures did not increase proportionally dueto the stitching. It can be considered that the stitchingparameters in the developed composite structures
DENSITY AND FIBER VOLUME FRACTION RESULTS OF VARIOUS DEVELOPED
COMPOSITE STRUCTURES [32, 33]
Label Density
(g/cm3)Total fiber volume
fraction
weight (volume)
(%)Fiber volume
fraction
weight (volume)
(%)Stitching yarn
volume fraction
weight (volume)
(%)Void content
(%)
U1 1.99 78.7 (61.2) 78.6 (61.2) – 3.34
U2 1.95 78.2 (59.4) 78.2 (59.4) – 5.11
U3 2.01 78.3 (61.1) 78.1 (61.1) – 2.60
N1 1.95 74.2 (56.2) – – 2.36
N2 1.81 74.7 (52.4) – – 10.27
N3 1.87 76.0 (55.3) – – 8.73
N4 1.91 77.5 (57.7) – – 7.30
M1 2.02 79.8 (62.7) 79.43 (62.4) 0.40 (0.31) 3.08
M2 1.98 79.0 (60.8) 78.2 (60.2) 0.78 (0.60) 3.84
M3 1.97 77.5 (59.6) 76.2 (58.6) 1.30 (1.00) 2.35
M4 2.00 79.8 (62.1) 79.1 (61.6) 0.63 (0.50) 3.62
M5 1.95 77.9 (59.1) 76.7 (58.2) 1.24 (0.94) 3.92
M6 1.95 76.8 (58.3) 74.8 (56.7) 2.05 (1.55) 2.28
M7 1.91 79.3 (59.1) 78.7 (58.5) 0.69 (0.52) 7.44
M8 1.92 78.2 (58.4) 76.9 (57.4) 1.34 (1.00) 5.63
M9 1.89 76.0 (56.0) 73.8 (54.3) 2.18 (1.61) 4.31
M10 1.92 77.7 (58.1) 76.7 (57.3) 1.09 (0.81) 5.29
M11 1.89 75.4 (55.3) 73.3 (53.8) 2.05 (1.51) 4.26
M12 1.87 77.3 (56.4) 73.9 (53.9) 3.46 (2.53) 5.30
NM 1.82 68.9 (48.3) 65.8 (47.2) 3.08 (1.02) 2.65Table 4

were stitching direction, stitching density and stitch-
ing yarn type.
Short beam results
Figure 4 shows the short beam strength and the spe-
cific short beam strength of 2D woven E-glass/polyester unstitched, unstitched/nano, multistitched/nano composite structures. Figure 5 shows the shortbeam strength and the specific short beam strengthof 2D woven E-glass/polyester multistitched compos-ite structures.
As seen in figure 4, the warp and weft
directional short beam strengths of the 2D unstitched(U1-U3) woven E-glass/polyester composite struc-tures varied from 23.60 to 17.47 MPa and from 20.51to 15.67 MPa, respectively. The warp and weft direc-tional short beam strengths of the 2D unstitched/nano (N1-N4) woven E-glass/polyester compositestructures varied from 23.05 to 16.94 MPa and from20.05 to 15.59 MPa, respectively. The warp and weftdirectional short beam strengths of the 2D multi-stitched/nano (NM) woven E-glass/polyester com-posite structure was 23.21 MPa and 19.54 MPa,respectively. It was found that the specific short beamstrengths of all unstitched, unstitched/nano and mul-tistitched/nano structures were proportional to theirwarp and weft directional short beam strengths. Thewarp and weft directional specific short beam
strengths of unstitched structures (U1-U3) werelower than those of the multistitched/nano structures(NM) but they were higher than those of unstitched/nano (N1-N4) except N3. In addition, the short beamstrength of U1 was higher than those of U2 and U3.When the nano silica material in the unstitchedE-glass/polyester composite structure increasedfrom 2.5 wt. % to 7.5 wt. %, the warp and weft direc-tional specific short beam strengths of the N1-N3structures increased. Also, it was found that therewas a slight difference between the warp and weftdirectional specific short beam strengths. Generally,the warp directional specific short beam strengths ofthe composite structures were higher than those ofthe weft. As seen in figure 5, the warp and weft directionalshort beam strengths of the 2D multistitched (M1-M12) woven E-glass/polyester composite structuresvaried from 19.91 to 17.16 MPa and from 20.79 to14.87 MPa, respectively. It was found that the specif-ic short beam strengths of all multistitched structureswere proportional to their warp and weft directionalshort beam strengths. In low modulus (stitching yarnNylon 6.6) lightly and densely stitched structures, thewarp and weft directional short beam strengths of the
131 industria textila 2016, vol. 67, nr. 2 ˘Fig. 3. SEM photos of 2D woven E-glass/polyester composite structures at 0°(warp direction):
(a) unstitched structure (U1); (b) unstitched/nano structure (N2); (c) multistitched structure (M12);
(d) multistitched/nano structure (NM)a b c d
Fig. 4. Short beam strength and specific short beam
strength of 2D woven E-glass/polyester unstitched,
unstitched/nano and multistitched/nano
composite
structures
Fig. 5. Short beam strength and specific short beam
strength of 2D woven E-glass/polyester multistitched
composite
structures

M4-M6 were slightly higher than those of the M1-M3.
In high modulus (stitching yarn Kevlar® 129) lightlyand densely stitched structures, the warp and weftdirectional short beam strengths of the M7-M9 werealmost the same with those of the M10-M12. It wasfound that the warp and weft directional short beamstrengths of densely stitched structures (M4-M6)were slightly higher than those of the lightly stitchedstructures (M1-M3). In addition, the warp and weftdirectional short beam strengths of high modulus(stitching yarn Kevlar® 129) lightly and denselystitched structures were slightly higher than those ofthe low modulus (stitching yarn Nylon 6.6) lightly anddensely stitched structures. When the stitching direc-tions increased, the warp and weft directional shortbeam strengths of low (stitching yarn Nylon 6.6) andhigh modulus (stitching yarn Kevlar® 129) lightly anddensely stitched structures slightly decreased due tosome filament breakages during stitching. Also, itwas found that there was a slight difference betweenwarp and weft directional short beam strengths.
Failure results after short beam test
Some of the failure results on various developed 2D
woven E-glass/polyester unstitched, unstitched/nano,multistitched and multistitched/nano composite struc-tures af
ter warp and weft directional short beam test
were investigated. Figure 6 shows the cross section-al views of unstitched and unstitched/nano 2D E-glass/polyester woven composites after warp andweft directional short beam load was applied. Figure7 shows the cross sectional views of multi stitchedand multistitched/nano 2D E-glass/polyester wovencomposites after warp and weft directional shortbeam load were applied. As seen in figure 6, thefailures of warp and weft directional 2D unstitched(U1-U3) and unstitched/nano (N1-N4) woven E-glass/polyester composite structures were observed as aform of major matrix breakages, and partial or totalfiber breakages on their top and bottom surfaces.The failures of warp and weft directional 2Dunstitched/nano silica woven E-glass/polyester com-posite structures showed more brittle behavior com-pared to the unstitched structures. In addition, theunstitched and unstitched/nano composites had
interlaminar shear failure between layers in theircross-sections and the failure was propagated to thelarge areas. Also, it was observed that there was aflexure failure in the top surface of structure as a formof compression and in the bottom surface as a formof tension. As seen in figure 7, the failures of warpand weft directional 2D multistitched (M1-M12) andmultistitched/nano (NM) woven E-glass/polyestercomposite structures were observed as a form ofmajor matrix breakages, and partial and complete fil-aments and yarn (tow) breakages on their surfaces.In addition, the multistitched and multistitched/nanocomposites had interlaminar shear failure betweenlayers in their cross-sections but the failure did notpropagate to the large areas. The interlaminar shearfailure occurred around the stitching yarn regions ata small area. Also, there was a flexure failure on thetop surface of structure as a form of compression andat the bottom surface as a form of tension in wherethe intra-yarn openings were observed.
CONCLUSIONS
The warp and weft directional specific short beam
strengths of unstitched structures were lower thanthose of the multistitched/nano structures. When thenano silica material in the unstitched E-glass/polyester composite structure increased, the warpand wef
t directional specific short beam strengths of
the unstitched/nano structures increased. When thestitching directions increased, the warp and weftdirectional short beam strengths of low (stitching yarnNylon 6.6) and high modulus (stitching yarn Kevlar®129) lightly and densely multistitched structuresslightly decreased due to stitching. In addition, thewarp and weft directional short beam strengths ofhigh modulus (stitching yarn Kevlar® 129) lightly and
132 industria textila 2016, vol. 67, nr. 2 ˘Fig. 6. Cross sectional (microscopic photos
at
×6.7 magnification) views of unstitched and
unstitched/nano 2D E-glass/polyester woven composites
after short beam strength test at warp and weft directions
Fig. 7. Cross sectional (microscopic photos at
×6.7
magnification) views of multistitched and multi-
stitched/nano 2D E-glass/polyester woven composites
after short beam strength test at warp and weft directions

densely multistitched structures were slightly higher
than those of the low modulus (stitching yarn Nylon6.6) lightly and densely multistitched structures. Theresults indicated that the stitching direction, stitchingdensity, stitching yarn, stitching type and the amountof nano materials in the composite structures wereimportant parameters. The failures of warp and weft directional two dimen-sional unstitched, unstitched/nano and multistitchedwoven E-glass/polyester composite structures wereobserved as a form of major matrix breakages, andpartial or total fiber breakages on their top and bot-tom surfaces. In addition, all composite structureshad interlaminar shear failure between layers in theircross-sections. But, the interlaminar shear failure inmultistitched and multistitched/nano structures did
not propagate to the large areas.
ACKNOWLEDGEMENTS
This work was partly supported by Erciyes University
Scientific Research Unit (EUBAP) under contract numberEUBAPFBD-10-3383.
The authors would like to thank the
Scientific Research Department of Erciyes University forthis invaluable support. The authors also would like tothank Erciyes University Technology Research andApplication Center (TAUM) for the mechanical testing ofthe composite materials. In addition, the authors would liketo thank Prof. Dr. Mustafa Guden for allowing the use ofcomposite lab facilities in İzmir Institute of Technology(IYTE) for this project.
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134 industria textila 2016, vol. 67, nr. 2 ˘Authors:
KADIR BILISIK*1
HUSEYIN OZDEMIR2
GAYE YOLACAN KAYA3
1Department of Textile Engineering, Faculty of Engineering
Erciyes University
38039 Talas-Kayseri, Turkey
2Vocational School of Technical Sciences
Gaziantep University
27310 Sehitkamil-Gaziantep, Turkey
3Department of Textile Engineering, Faculty of Engineering and Architecture
Kahramanmaras Sutcu Imam University
46100 Kahramanmaras, Turkey
Corresponding author:
KADİR BİLİȘİK
e-mail: kadirbilisik@gmail.com; kbilisik@erciyes.edu.tr[19] Godara, A., Gorbatikh, L., Kalinka, G., Warrier, A., Rochez, O., Mezzo, L., Luizi, F., Vuure, A.W., Lomov, S.V.,
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INTRODUCTION
The current trend to use natural fibers as reinforce-
ment material is explained by the fact that they pre-sent good mechanical properties comp ared to fiber
glass, have a low density
, a low cost and a high
spreading degree [1–3]. Also, the natural reinforce-ment fibers confer to the composite materials withsynthetic matrix a biodegradable character, whichmotivates the concerns in the field.Cotton represents a type of reinforcement fibers, veryoften used in engineering. The mechanical strengthof a composite increases with the percentage of cot-ton fibers if they are under the form of fabric [4–5].Pamuk and Ceken studied the variation of tensile,compression and impact strength, of an epoxy resinreinforced with flax or cotton fibers as knitted pre-forms and showed that this type of materials havemechanical properties superior to resin [6]. This isexplained by the fact that the natural fibers used forreinforcement have mechanical properties much bet-ter than the composite matrix [7]. Alomayri et al. stud-ied the influence of the short cotton fiber percentageon the flexural and tensile strength in a compositeand established that the optimum value for it is 2.1%[8]. They investigated the impact strength and frac-ture toughness of the same material with differentcotton fiber percentages (3.6% up to 8.3%), examin-ing also the fracture surface of the composite materialusing scanning electron microscopy, [9]. The authors
showed that the higher the cotton fiber percentage,the higher the fracture toughness, due to the uniqueproperties of cotton fibers in withstanding greaterbending and fracture forces than the more brittlegeopolymer. Wu et al., prepared composite materialshaving polypropylene matrix reinforced with cottonstalk bast fibers (CSBF) and tested their mechanicalproperties (flexural strength, tensile strength andimpact strength) [10]. Properties of the same compos-ite material were also investigated by Qu et al. [11].Their results revealed that the incorporation of CSBFdecreased the tensile and impact strength, while sig-nificantly enhanced the flexural strength, flexural mod-ulus and tensile modulus. The influence of water con-tent in CSBF during the explosion and fiber contenton the mechanical properties was also studied, theauthors concluding that biocomposites reinforced byfibers with 40 and 50 wt% water contents during theexplosion had the best mechanical properties.The properties of reinforced materials with naturalfibers motivate the fact that their practical applica-tions are numerous, from packages to car industrycomponents [12–13]. This work presents a compos-ite material obtained from polyester resin reinforcedwith cotton fabric with a mass percentage of 35%.Three point bending tests were performed to inves –
tigate the mechanical properties. A finite elementREZUMAT – ABSTRACT
Studiu privind utilizarea unui compozit armat cu fibre de bumbac pentru obținerea căștilor de protecție
Scopul acestei lucrări este de a evalua proprietățile mecanice ale unei rășini poliesterice armate cu fibre de bumbac și
de a prezent a o aplicație practică pentru acest material.
Au fost efectuate încercări mecanice de încovoiere în trei
puncte, în scopul determinării caracteristicilor mecanice ale materialului studiat. Valorile obținute au fost utilizate înanaliza cu metoda 3D a elementelor finite. Rezultatele obținute în urma analizei numerice au evidențiat faptul cămaterialul studiat poate fi utilizat cu succes pentru realizarea căștilor de protecție. Studiul se poate extinde pentru altetipuri de elemente de protecție utilizate în activități sportive sau industriale.
Cuvinte-cheie: biodegradabil, bumbac, element finit, analiză dinamică, teste mecanice
Study regarding the use of a cotton fiber reinforced composite for obtaining protection helmets
The objectives of this work are to evaluate the mechanical properties of an unsaturated polyesteric resin reinforced with
cotton fibers and to present a practical application of this material. Three point bending tests have been performed inorder to determine the mechanical characteristics of the studied material. The obtained values were further used in a3D finite element analysis. The numerical results revealed the fact that the studied material can be successfully usedfor manufacturing protection helmets. The study may be extended to other types of protection elements used in sportsor industrial activities.
Keywords: biodegradable, cotton, finite element, dynamic analysis, mechanical tests
135 industria textila 2016, vol. 67, nr. 2 ˘Study regarding the use of a cotton fiber reinforced composite
for obtaining protection helmets
VIRGIL TUDOSE HORIA GHEORGHIU
RADU FRANCISC COTERLICI STEFAN DAN PASTRAMA
DANIELA TUDOSEGE

calculation model of a protection helmet was further
realized, using the mechanical characteristicsobtained following the bending tests. The calculationresults showed that, from the point of view of themechanical strength, this material can be used formanufacturing protection helmets, since the maxi-mum dynamic stresses obtained from the numericalanalysis are much smaller than the ultimate strengthof the material.Following the study presented herein, a subsequentresearch direction could involve the study of the influ-ence of this material upon the helmet placed on thehead, during the impact. Also, another importantaspect is represented by the choice of appropriateinterior jacketing (foams or other types of elastic ele-ments). There are several studies in the literaturewhich show the importance of the helmet materialregarding its influence over the head during theimpact and the effect of various types of internal jack-eting [14–17].The analysis of such composite materials can also beextended for other types of industrial protection ele-
ments.
EXPERIMENTAL WORK
Materials and method
For the experimental research, commercial cotton
and an unsaturated polyester resin were purchased.The unsaturated polyester resin is a thermoset.Thermosetting polyesters are commonly used infiber-reinforced plastics, epoxies being the mainunsaturated polyester used in the current market foradvanced composites resins. Initially
, the viscosity of
these resins is low; however, thermoset resins under-go chemical reactions that crosslink the polymerchains and thus connect the entire matrix together ina three-dimensional network. This process is calledcuring. Thermosets, because of their three-dimen-sional cross-linked structure, tend to have highdimensional stability, high-temperature resistance,and good resistance to solvents. It is usual to refer tounsaturated polyester resins as “polyester resins”, orsimply as “polyesters”. On the other hand, saturatedresins are thermoplastic. Unlike the curing process ofthermosetting resins, the processing of thermoplasticsis reversible, and, by simply reheating to the process
temperature, the resin can be formed into anothershape if desired. Thermoplastics, although generallyinferior to thermosets in high-temperature strengthand chemical stability, are more resistant to crackingand impact damage [18–19]. Due to the better chem-ical and thermal resistance, an unsaturated resin waschosen as matrix of the studied green compositematerial. Figure 1 presents the Hand Lay-up method, appliedto obtaining cotton fabric/unsaturated polyester resincomposite plate with five layers.For the composite matrix, Nestrapol 450-66 unsatu-rated polyester resin was used and, for reinforce-ment, a cotton fabric with a mass percentage of 35%was considered. By the hand lay-up process, resinwas cast alternatively between five layers of cottonfabric, the total thickness being 2.75 mm. The mate-rial thus obtained was left seven days for hardening,at a temperature of 20șC.
Three point bending test results
Five samples for three point bending were manufac-
tured, according to SR EN ISO 14125, and presentedin figure 2 [20].
The samples dimensions were: length
– 80 mm, width – 15 mm and thickness – 2.5 mm.The three point bending tests were performed with aLR5K Plus machine from Lloyd Instruments (figure 3)
136 industria textila 2016, vol. 67, nr. 2 ˘Fig. 1. Hand Lay-up method
Fig. 2. Composite samples
Fig. 3. LR5K Plus machine and three point bending test

at a temperature of 20 șC. The loading rate was 5
mm/min. Figure 4 shows the characteristic curve ofmaterial, obtained by the average of the valuesresulted following the five sample tests and the linetangent to the curve in the origin, whose slope is theinitial Young’s modulus E. A value of 1200 MPa wasobtained for this elastic constant.We notice that the average tensile strength for thismaterial is about 50 MPa. The failure is suddenbecause the cotton fabric takes the load after thepolyester resin creeping. The percent elongation isabout 20%, which is not relevant for this research. Ifone considers that the material has a linear behaviorand Young’s modulus is 1200 MPa, the characteristiccurve would be represented by the red line in figure4. We can notice that, for a certain specific deforma-tion, the stress is always higher if the material behav-ior is considered as linear and thus, the analysis in
this case is conservative.NUMERICAL ANALYSIS
Numerical model
The numerical analysis, performed with the finite ele-
ment sof
tware ANSYS LS-DYNA, simulated the
impact on a protection helmet, using a 5 kg sphericalbody, left to fall free from one meter height, accordingto the standard EN 397 [21–22]. For the simplificationof the numerical model, the helmet material was con-sidered to be isotropic and linear. The obtainedresults confirm that this hypothesis is reasonable,since the maximum stresses obtained from the finiteelement analysis is less than 23 MPa, value up towhich the differences between the real curve and thelinear approximation are small. Thus, an analysisusing the real curve is not justified in this case, sav-ing computing time and resources. The geometry of the protection helmet is shown infigure 5,  a. The impacting body was modeled as a
steel sphere, having a diameter of 107 mm. Figure 5,  b
presents the helmet’s dimensional parameters.Table 1 presents the characteristics of the materialsof the two bodies and their dimensions. Figure 6gives the mesh of the helmet, the imposed boundaryconditions (movement constrained on the impactdirection) and the mesh of the impactor.The mesh was built using SHELL 163 elements, forthe helmet mesh, and SOLID 164 elements, for theimpacting body [21]. The thickness of the SHELL ele-ment was 4 mm, equal to the thickness of the mate-rial used in the manufacturing of the helmet. The
imposed load was an acceleration of 9.81 mm/s
2for
137 industria textila 2016, vol. 67, nr. 2 ˘Fig. 4. Stress-strain curve of composite and initial slope
of Young’s modulus
Fig. 5. Geometry (a) and dimensions (b) of helmet
a b
Table 1
Characteristics Helmet Sphere
Young’s modulus [MPa] 1200 21·104
Poisson ratio 0.28 0.3
Mass density [kg/m3] 1500 7800
Dimensions [mm]L = 230
L = 200
h = 110Diameter = 107

the sphere. The results were obtained following 50
integration steps.
RESULTS AND DISCUSSIONS
In order to verify the accuracy of the parameters
introduced in the numerical calculation, the evolutionin time of the imp
acting body velocity was plotted
from the numerical results in figure 7. One can noticethat the sphere falls free from a height of one meterin around 0.44 s and reaches, at the moment ofimpact, a velocity of (– 4.32 m/s). After 0.02 s, thevelocity decreases to zero (moment when the defor-mation of the helmet is maximum) and then reboundoccurs in 0.02 s with a velocity of 2.2 m/s. Thus, aloss of energy of the impactor occurs, which shouldbe recovered in the residual deformation of the hel-met, presented further in this paper. The 4.32 m/simpact velocity obtained from the numerical analysiscan be verified using the kinematics equations:
2h 2 × 1t=
√ = √ = 0.452 s ;g 9.81
v= g× t= –9.81 × 0.452 = –4.43 m/s.
The very small differences between the results ( about
2.7%) show that the parameters were correctlyintroduced and can be diminished considerably if the
number of integration steps increases.Figure 8,  apresents the equivalent von Mises stress
at the moment t = 0.46 s, when the maximum stress
value is recorded in the structure. This value wasobtained in node 1393 (figure 8,  b). Figure 9 presents
the evolution in time of the equivalent von Misesstress in this node. One can notice the maximum ofthe obtained curve, corresponding to the impactmoment and the range within which the stressdecreases and is stabilized, corresponding to the
138 industria textila 2016, vol. 67, nr. 2 ˘Fig. 6. Mesh structure and constraints of helmet
Fig. 8. Von Mises stress field at t = 0.46 s (a) and node number 1393 position (b)
Fig. 7. Rate evolution in time of the impacted
body velocity
a b

period after the rejection of the sphere. The stress
does not reach the value zero after the impact, as itshould happen for an elastic structure, because thehelmet is deformed in such a manner as it cannotreturn to its initial form (is clogged) and remainsstrained, as one can see in figure 10, which revealsthe structure deformation.
CONCLUSIONS
From the point of view of mechanical strength, the
material proposed for manufacturing a protection hel-met meet
s the requirements. From the numerical
analysis, a maximum equivalent stress was obtainedat the simulated impact test of the helmet, muchbelow the material’s ultimate strength.In figure 4, we can notice that the von Mises stress
obtained from the calculation is higher than the realones, as, in the finite elements analysis, the materialwas considered to be linear elastic. Thus, theobtained results can be considered as conservative.Since the mechanical properties obtained for thestudied biocomposite material are comparable withthose of composites reinforced with glass or carbonfibers, the cotton fiber reinforced material representsan ecological alternative in engineering applicationsof classic composites. In some practical applications,flexibility or a low stiffness may be required. In suchcases, the low Young’s modulus of this material is anargument for its practical use. The food industry is afield where the researches regarding the ecologicaland biodegradable materials are motivated not onlyby the mechanical characteristics, but also by thehealth norms imposed.In a future study, the effects of the impact on the hel-met placed on the head will be analyzed, for differentelastic elements or foam jacketing used inside it. Thisaspect is important as the impact energy is absorbedin different ways, depending on the elements insidethe helmet. A complex finite element model will bealso developed, to take into account the anisotropicand non-linear character of the helmet material, aswell as the internal elements of the helmet and itsclamping on the head.
Acknowledgements
The work of Virgil Tudose has been funded by the Sectoral
Operational Programme Human Resources Development2007-2013 of the Ministry of European Funds through theFinancial Agreement
POSDRU/159/1.5/S/134398.
Radu Francisc Coterlici wishes to acknowledge theStructural Funds Project, Sectoral Operational ProgrammeHuman Resources Development (SOP HRD), ID137516and the Structural Founds Project PRO-DD (POS-CCE,O.2.2.1., ID 123, SMIS 2637, ctr. No 11/2009) financedfrom the European Social Fund and by the RomanianGovernment respectively for providing the infrastructureused in this research work.
139 industria textila 2016, vol. 67, nr. 2 ˘Fig. 9. Evolution in time of von Mises stress field
for node 1393
Fig. 10. Helmet deformed shape after impact moment
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Authors:
VIRGIL TUDOSE
DANIELA
TUDOSE
HORIA GHEORGHIU
STEFAN DAN PASTRAMA
University Politehnica of Bucharest
Faculty of Engineering and Management of Technological Systems
Splaiul Independentei nr. 313, Sector 6, 060042 Bucharest, Romania
e-mail: virgil.tudose@upb.ro, daniela.tudor@upb.ro,
hgheorghiu@yahoo.com , stefan.pastrama@upb.ro
RADU FRANCISC COTERLICI
Transilvania University, Department of Materials Science,
Bulevardul Eroilor nr. 29, 500036, Brasov, Romania
e-mail: coterliciradufrancisc@yahoo.com
Corresponding author:
STEFAN DAN PASTRAMA
stefan.p
astrama@upb.ro

INTRODUCTION
This article presents a study on design and construc-
tion of adapted p
atterns for people suffering from
scoliosis. Scoliosis can be understood as a medicalcondition represented as a three-dimensional devia-tion of the spinal axis [1]. It is defined as a spinalcurvature of more than 10 degrees to the right or leftas the examiner faces the patient (in the coronalplane). Deformity may also exist to the front or back(in the sagittal plane) [2]. Within this study we haveinvestigated the possibilities of virtual prototypingof garments and CASP (Curvature, Acceleration,Symmetry, Proportionality) methodology for evalua-tion of the shape of surfaces. The methodologyproved to have a significant potential for constructionof adapted pattern designs in order to produce gar-ments for people suffering from scoliosis or otherbody deformations. CASP has been developed by a
group of researchers at the University of Maribor andrepresents a new attempt to describe the shape ofdifferent surfaces using four classification properties[3]. The methodology is described in more detailsbelow
GARMENTS FOR PEOPLE SUFFERING FROMSCOLIOSIS
It is not easy to find appropriate, well-designed and
well-fitted garment
s for people with scoliosis. They
are often faced with a problem how to dress nicelyand comfortable. Different advices can be found in lit-erature and lately on specialized webpages or blogs,such as [4–6]. Approximately 4% of the populationhas scoliosis. Scoliosis can cause visible symptoms:uneven shoulders, head not centered, ribs different
141 industria textila 2016, vol. 67, nr. 2 ˘REZUMAT – ABSTRACT
Construcția articolelor de îmbrăcăminte adaptate persoanelor cu scolioză
utilizând
prototiparea virtuală și metoda CASP
Obiectivul studiului prezentat în acest articol este de a explora o nouă modalitate de proiectare și realizare de prototipuri
virtuale ale articolelor de îmbrăcăminte, adaptate persoanelor cu scolioză. Persoanele cu scolioză se confruntă cuprobleme zilnice legate de achiziționarea și utilizarea de articole de îmbrăcăminte adecvate, ajustate pe corp șiconfortabile. Considerăm că putem îmbunătăți aspectul și ajustarea pe corp a îmbrăcămintei purtate de persoanele cuscolioză prin construirea unui model de îmbrăcăminte adaptat, ținând seama de zonele deformate ale corpului. Dinacest motiv, s-au aplicat instrumente și metode virtuale avansate, cum ar fi CASP (Curbură, Accelerare, Simetrie,Proporționalitate), pentru construirea tiparului de îmbrăcăminte adaptat la modelul 3D al corpului deformat din cauzascoliozei. În acest fel, este posibil să se îmbunătățească aspectul optic al articolului de îmbrăcăminte și ajustareaacestuia pe corp. Cu un design adaptat al articolului de îmbrăcăminte, s-a proiectat o rochie cu un aspect mai bun alcusăturii pe partea din spate, precum și ajustarea în zona omoplaților. Rezultatele studiului au confirmat faptul căprocesul de reconstrucție a modelului de bază al rochiei îmbunătățește aspectul și ajustarea acesteia pe un corpdeformat.
Cuvinte-cheie: construcția articolului de îmbrăcăminte, modele adaptate, scolioză, metodă CASP, analiza suprafeței
Construction of adapted garments for people with scoliosis using virtual prototyping and CASP method
The goal of the study presented in this article is to explore the new way to design and produce virtual prototypes of
garments, adapted for people with scoliosis. People with scoliosis are faced with everyday problem related to purchaseand use of suitable, well-fitted and comfortable garments. Our assumption was that we can improve the appearance andfit of the garment to the person with scoliosis by constructing the adapted garment pattern design ,taking into account
the deformed areas of the body. For this reason we have applied advanced virtual tools and methods, such as CASP(Curvature, Acceleration, Symmetry, Proportionality), for constructing the garment pattern designs adapted to the 3Dbody model deformed as a consequence of scoliosis. In this way, it is possible to improve the optical appearance of thegarment and its fit to the body. With adapted dress pattern design, we succeeded to design a dress with betterappearance of the seams on the back as well as the fit in the area of shoulder blades. The results of the study confirmedthat reconstruction process of the basic dress pattern design improves the appearance and fit of the dress to a deformedbody.
Keywords: garment construction, adapted patterns, scoliosis, CASP method, surface analysisConstruction of adapted garments for people with scoliosis using virtual
prototyping and CASP method
ZORAN STJEPANOVIČ TANJA KOCJAN STJEPANOVIČ
ANDREJ CUPAR ANDREJA RUDOLF
SIMONA JEVŠNIK

heights, a shoulder blade that sticks out more than
the other, uneven hips, one leg appearing shorterthan the other, the body leaning to one side. Moresevere cases will present with more severe outwardappearance of these symptoms [7–9]. Because scol-iosis causes this asymmetry in the body, imperfectly-fitting clothing can become an everyday problem.The waist on pants or skirts may appear uneven orshirts and dresses may not fit or hang on the bodyproperly. Dressing in a way that makes the individualfeel best and secure with their scoliosis can becomea challenge [4–5]. One of the easiest ways to maskscoliosis is avoid tightly fitting clothing. Individualswith scoliosis tend to be small framed, and longwaisted, so their bones are very pronounced. Tightshirts can reveal the asymmetry more obviously. Notonly can clothing like tight t-shirts and blousesemphasize scoliosis more, but because there is anasymmetry one side might feel much tighter than theother making these types of clothing uncomfortable[6]. A scoliotic and a normal spine are presented infigure 1 [10].
EXPERIMENTAL PART
3D body models
In our study, we focused on design and construction
of garment
s, adapted for people with scoliosis. Our
assumption was that we can improve the appearanceand fitting of the garment on the person with scoliosisby constructing the adapted garment pattern designtaking into account the deformed areas of the body.For this reason, we have prepared a synthetic 3Dbody model using Makehuman software, figure 2[11]. As it can be seen from the figure, the gray modelrepresents a normal body and the green one a modelwith scoliosis. The spine is curved, which causes theleaning of the body model in the area of the shoulderblade to the left. Consequently, left shoulder blade isprotruding from the normal plane. 3D body modelwas finally improved using Blender software, figure 3[12]. Idealized human body is symmetric. The producersof ready-made garments cannot consider the defor-mations of the body, caused by scoliosis, becausethey are specific and differ from case to case.
Therefore, the only solution to improve the appear-ance and fit of the garment seems to be an individu-al approach to this problem. This means that it is nec-essary to study the deformation areas of the bodyand construct adapted garment pattern designs foreach case individually.
Introduction of CASP method
For the purpose of analysis of the deformed areas of
a human’
s body, we have applied in this study a new
method called CASP (Curvature, Acceleration,Symmetry, Proportionality). CASP was originallydeveloped as a method for classification of perceptu-al surfaces and for analyzing digital geometry [3,13–14]. Methodology of surface evaluation wasdeveloped to establish the meta-language in design
142 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 1. Scoliotic and a normal spine
Fig. 3. Improvement of a 3D body model using
Blender software
Fig. 2. Normal (gray) and scoliotic synthetic
female body (green)

communication, which was perceived as necessary
part of styling. The first step was analysis of existinggeometry and the second a synthesis of newly creat-ed geometry considering desired property. There arefour properties ,which characterize surfaces similar to
colors in color space [15], where each color is repre-
sented as a mix of values L*, a* and b*.
The surface’s geometrical space consists of thesefour properties:
●Curvature – C,
●Acceleration – A,
●Symmetry – S and
●Proportionality – P.
A surface is indicated as (C, A, S, P). Curvature goesfrom – to + sign. Zero determinates a neutral curva-ture and represents a plane. Negative values mean aconcave surface and positive values are for convexsurfaces, figure 4 [3, 13–14]. They are evaluated withsign and values of entities in n×n
10matrix. Value is
calculated as arithmetic average of normalized n×n
distances including a preposition sign. The n×n
matrix follows natural directions and is not the sameas in mathematical writing. It has swapped rows overmiddle row. Therefore, the matrix starts with entry(0,0) at bottom left corner as shown in expression (1).
a
n–1,0… an–1,n–1
[⋮⋮](1)
a0,0… a0,n–1
Starting point marked with (0,0) is at the bottom leftside on analyzed surface, same as in n×n matrix.
This enables to locate position of same point in 3Dspace and in n×nmatrix.
Acceleration is a characteristic of an elementary sur-face, which is observed in a longitudinal direction,
figure 5 [3, 13–14]. Figures 4–7 have been originally
created by the authors from the University of Maribor,Slovenia, within the research related to the CASP
methodology development [3, 13–14].Symmetry takes just positive values. Zero meansperfect symmetry of a surface observed over middlecolumn of n×n matrix, figure 6 [3, 13–14]. Symmetry
can be detected as differences between entities pairscompared over the middle column. The first and lastcolumn are compared and second and the last butone. The middle one stays untouched in this case.Symmetry is calculated as arithmetical average of allentity pairs. Proportionality, figure 7, is the fourthproperty to indicate the size or width of the surface [3,13–14]. It is calculated as a ratio between the lengthand width of the observed surface, projected on atriangular plane.The whole n×nprocedure is based on the use of a
graphical algorithm Grasshopper® (GH), which istightly integrated with 3D modelling tool Rhinoceros(RH) [16–17]. Grasshopper is an add-on and runswithin the RH application. Procedures are created bydragging components onto a canvas. Outputs ofthese components are then connected to the inputsof subsequent components. Grasshopper is mainlyused to build generative algorithms and it acts like aprogramming tool. Many of Grasshopper’s compo-nents create 3D geometry. Procedures may also pro-cess other types of algorithms including numeric, tex-tual, audio-visual or haptic applications. GH is usedbecause of complex algorithms that can be used out
143 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 4. Curvature
Fig. 5. Accelerated surface
Fig. 6. Symmetry
Fig. 7. Proportionality

of the box and can be easily connected and com-
bined. The whole procedure for analyzing digitizedsurface geometries is based on 10 steps, describedin [3, 14].
RESULTS AND DISCUSSION
Both body models, presented in figure 2, were ana-
lyzed using the CASP
method in the shoulder area,
figure 8. Scoliotic deformation in the left shoulderarea is represented in figure 9. The blue line followsthe curve of the normal body. Deformation in the leftshoulder area is seen in the form of a black curve,following the shape of a scoliotic shoulder blade,figure 9.For the normal model we got the following CASP val-ues, measured in the observed shoulder area:
CASP: (–0.12 ; –0.64 ; 10.30 ; 1.11)
The analysis of the deformed model resulted withthese values:
CASP: (–3.06 ; 15.30 ; 185.31 ; 1.17)
Differences in CASP properties are primarily in sym-metry, which is expected, since we artificially createdthe asymmetry. There are also greater values ofCurvature and Proportionality. Since it is a compositesurface, the Acceleration does not have the samemeaning as in elementary surfaces, therefore it willnot be considered for this case. Interesting and usefulare the cross-sections in the examined area of the
body. They can be used for the method DEGI (Designwith Existing Geometry Implementation) or generallyfor the analysis of the curvature of the model in a par-ticular cross-section [3].The dress basic pattern design was constructedaccording to normal (symmetric) synthetic femalebody dimensions by using rules of the constructionsystem M. Müller&Sohn and Optitex CAD/PDS sys-tem, figure 10 [18–19]. The virtual fitting of the basicdress pattern design on the normal and scoliotic syn-thetic female bodies are shown in figure 11. It is evi-dent that differences in CASP values are also reflect-ed in the appearance of the dress, figures 11, 13, 14,15. The deformed body is asymmetric, therefore, thestraight seam in the middle of the back, figure 11 (a),because of convex blade, is moved to the right andappearance of the dress enhances asymmetry of thebody, figure 11 (b). Also the movement of the dartsand their asymmetry according to the body can be
144 industria textila 2016, vol. 67, nr. 2 ˘
Fig. 8. Cross-section parts on the back for a normal body (left) and deformed body (right)
Fig. 9. Scoliotic deformation in the left shoulder area
Fig. 10: Basic dress pattern design

seen, as well as shortening of the dress on the right
side of the body.With reconstruction of the basic dress pattern designwe wanted to improve the visual appearance and bal-ance of the asymmetric body. For this reason wehave observed the shoulder area in both normal andscoliotic body. Using the Optitex software functionswe have determined average Tension XY andTension X above all in the area, marked in figure 12. Graphical results of the tension analysis of combina-tions related to normal/deformed body and normal/adapted dress are presented in figures 13–15. It canbe seen from the tension map that we successfullylowered the tension and therefore also fit and wear-ing comfort of the garment in the shoulder area.We have also performed the statistical analysis ofresults using the F- and t-test regarding the values of
145 industria textila 2016, vol. 67, nr. 2 ˘Fig. 11. Basic dress pattern design on the normal (a) and scoliotic (b) synthetic female body
a b
Fig. 13. Tension analysis for a normal body and normal dress
Tension XY 1.45 fg/cm Tension X 0.28 fg/cm
Fig. 14. Tension analysis for a deformed body and normal dress
Tension XY 1.46 fg/cm Tension X 1.09 fg/cm
Fig. 12. Determination of Tension XY and Tension X
in the investigated left shoulder area

Tension XY and Tension X. Namely, differences are
seen above all in transverse direction (direction of theweft in the fabric). The results regarding the compar-ison of combinations deformed body/normal dressand deformed body/adapted dress are in table 1. Based on this analysis, and with an inspection of thedeformation areas of the body and dress the reloca-tions of the dress side seams, waist seams, backmiddle seam in the blade area were performed, aswell as relocations of the waist, breast and bladedarts, figure 16.Virtual prototype of the adapted basic dress patterndesign to a scoliotic female’s body is presented infigure 17. When comparing figures 11 (b) and 17 it isclearly visible that reconstruction process of the basicdress pattern design improves the appearance and fitof the dress to a deformed body. The seam in themiddle of the back is aligned, darts are symmetrical
with respect to the center of the
body. Seam line in the waist anddress edge are aligned. We haveintentionally chosen the sensitivecheckered fabric pattern.
CONCLUSIONS
In this study we have shown that
advanced virtual tools and meth-ods, such as CASP
, can be used
for constructing the garment pat-tern designs adapted to the 3Dbody model deformed as a conse-quence of scoliosis. When design-ing patterns for garments we com-monly use the functionalities ofcomputer-based pattern-designsystems (PDS). In this study, wehave used the Optitex PDS. The
146 industria textila 2016, vol. 67, nr. 2 ˘Fig. 15. Tension analysis for a deformed body and adapted dress
Fig. 17. Adapted (reconstructed) basic dress pattern design on a deformed body
Tension XY 1.45 fg/cm Tension X 0.64 fg/cm
RESULTS OF STATISTICAL ANALYSIS RELATED TO TENSION XY AND TENSION X
Comparison between DB-ND and DB-AD
FcalcFtabH0: s1= s2TcalcTtab Significance of difference
Tension XY 0,27 0,43 Accept 0,49 2,06 Statistically insignificant
Tension X 0,74 0,43 Reject 9,37 2,04 Statistically significantTable 1
Fig. 16. Comparison between basic dress pattern design
for the normal (grey) and scoliotic female (red)

functionalities works well for patterns, intended for
garments for people without body deformations. Incases, related to the pattern design of adapted gar-ments for people with body deformations, such asthose seen in scoliotic bodies, we need to apply addi-tional analyses, because commercial PDS packagesdo not offer functionalities for supporting specialrequirements. CASP method for evaluation of shapeof surfaces, which was originally developed as anal-ysis tool and classification methodology of percep-tional surfaces in product design, was successfullyused in this study for analyzing the deformed areas ina scoliotic body. The results, CASP values andcurves, following the deformed left shoulder blade,were then used for constructing the adapted female’sdress. In such a way, an engineered approach wasapplied and realized in the area of garmentdesign/construction. Beneficial outcomes can beseen as improved optical appearance of the garmentand its fit to the body. From the tension maps, pre-sented in figures 13–15, it can be seen that we suc-cessfully lowered the tension and therefore also fitand wearing comfort of the garment in the shoulderarea. Already minor reduction of tension appearingin a garment contributes significantly to wearingcomfort, which is very important in cases of deformed
bodies. With an adapted dress pattern we succeeded todesign a dress with better appearance of the seamson the back as well as the fit in the area of shoulderblades. It can be concluded that the potential of suchapproach can be recognized as a promised one. Thegarments made using adapted pattern designs fit thepersons with scoliosis better, even tight clothes, suchas a dress, presented in this article. Such garmentscan definitely rise the confidence and self-esteem ofmodern women suffering from scoliosis since theyare not forced to use only loose clothes. Our furtherresearch will include garments for men suffering fromscoliosis. We also intend to extend our studies usingCASP method towards the virtual prototyping ofadapted garments for people with other body defor-mations and people with limited body mobility (some
preliminary studies already published in [20, 21, 22] ).
ACKNOWLEDGMENT
A part of this study belongs to the Adva2Tex ERASMUS+
project, which has been funded with support from theEuropean Commission.
This publication reflects the views
only of the author, and the Commission cannot be heldresponsible for any use which may be made of the infor-mation contained therein.
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Authors:
ZORAN STJEPANOVIČ1
ANDREJ CUPAR1
SIMONA JEVŠNIK2
TANJA KOCJAN STJEPANOVIČ3
ANDREJA RUDOLF1
1University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor, Slovenia,
e-mail: zoran.stjepanovic@um.si, webpage: http://www.fs.uni-mb.si/
2Istanbul Technical University, Faculty of Textile Technologies and Design, Istanbul, Turkey
e-mail: simonajevsnik@gmail.com
3DOBA Faculty of Aplied Business and Social Studies Maribor, Slovenia
e-mail: tanjaks@prava-poteza.si