THE 10th INTERNATIONAL SYMPOS IUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING [615075]

THE 10th INTERNATIONAL SYMPOS IUM ON ADVANCED TOPICS IN ELECTRICAL ENGINEERING
March 23 -25, 2017
Bucharest, Romania

PAN/ZnO composite electrospun fibers for
UV shielding applications

Abstract – The aim of the presented work in this paper is to
chemical synthes is of ZnO nanoparticles for PAN/ZnO
electrospun composite fiber with UV shielding. During this work
was study t he influence of temperature of chemical synthesized
on ZnO nanostructures structural and morphological
proprieties. Composite fibers were electrospun using a
PAN/ZnO solution in dimethylformamide (DMF). The effects of
composition of polymer solutions on th e morphological
characteristics and UV shielding of fibers was investigated .

Keywords : polyacrylonitrile , ZnO, electrospinning, UV shielding

I. INTRODUCTION
In order to reduce the risk of skin injury associated with
ultraviolet exposure, appropriate clothing and a sunscreen
have been considered as effective protection from sun and skin
cancer prevention. Therefore, extensive research efforts hav e
been devoted to developing UV shielding material which may
be ideal for UV protective coating. Modern sunscreens contain
nanoparticles of wide bandgap semiconductor (TiO 2, ZnO)
materials for UV -protection as they have a large surface area –
to-volume ratio , they significantly increase the effectiveness to
block UV radiation when compared to bulk materials [ 1, 2].
UV radiation is a part of the electromagnetic spectrum with a
wavelength ranging from 100 to 400 nm, and comprises three
bands: UVA (315 to 400 nm ), UVB (290 to 315nm), and UVC
(100 to 290 nm). The terrestrial solar UV received consists of
only UV with wavelength 290 – 400 nm, because UVC and
some UVB are absorbed by the stratospheric ozone in the
earth atmosphere [ 3].
Zinc oxide nanostructure have been found wide ranging of
applications in various areas due to its unique and superior
physical and chemical properties compared with bulk [ 4].
Due to the interest of this material various chemical method
was developed in order to obtain ZnO with differen t shape
and morphology. Methods such as thermal decomposition [5],
chemical vapo ur deposition [6], sol gel [7], spray pyrolysis
[8], and precipitation [9] have been developed for the
fabrication of nanosized ZnO particles with uniform
morphology and size [ 10-12].
The electros pun polymer composite membrane with ZnO
filler material, can act as a physical filter against the UV -B
and particularly UV -A radiation of the sun [13-15]. Electrospinning is a simple and versatile process by which
polymer nanofibers can be produced using an electrostatically
driven jet of polymer solution [16, 17]. The electrospinning
technique also provides the capacity to lace together a variet y
of types of nanoparticles or nanofillers [ 18]. This composite
fibers are expected to find applications in a varieties domains:
ultraviolet shielding [19] and ant ibacterial [20].
In this work, was synthesized and characterized zinc oxide
nanostructures and PAN/ZnO electrospun composite fibers.
During this work was study t he influence of temperature of
chemical synthesized on ZnO nanostructures structural and
morphological proprieties. Composite fibers were electrospun
using a PAN/ZnO solution in dimethylformamide (DMF).
The effects of composition of polymer solutions on th e
morphological characteristics and UV shielding of fibers was
investigated .

II. EXPERIMENTAL
A. Materials
PAN fibers as polymer source w ere purchased from
Bluestar Fibres Co. Ltd. The ZnO nanostruct ured additives,
were obtained by co -precipitation method using as precursors
ZnCl 2 (Alfa Aesar) and NaOH (Chemical Compay). The
solvent used for dissolving PAN and for PAN/ZnO dispersion
was dimethylformamide (DMF), purchased from Alfa Aesar.
All reagents were used as received, without further
purification.
B. ZnO nanopa rticles chemical synthesis
ZnO nanoparticles have been synthe tized by wet chemical
method followed by thermal treatment [ 21], using as
precursors: ZnCl 2 and NaOH. Appropriate amount of zinc
chloride was dissolved in water for obtaining a solution 10M .
Once the zinc chloride solution is complete ly dissolved, 5M
NaOH solution was added drop by drop. After the complete
addition of sodium hydroxide , the obtained solution was
heated at 80oC, 85oC and 90oC and maintained for 2h with
magnetic stirring. After the complete reaction (2h), solution
was allowed to settle and white precipitate was washed with
distilled water for ten times. After washing, the precipitate
was filtered and thermal treated in oven at 400oC for 1 hour.
The final product ZnO was characterized from morpho –
structural point of view .
C. Preparation of electrospun composite nanofibers
In PAN/ZnO solution preparation process, it is important
that the filler (ZnO) to be uniform dispersed in polymer

(PAN ) suspension. ZnO nanopowder (< 60nm) was ultraso nic
dispersed in DMF at 0oC for 30 min. PAN filaments was
dissolved in obtained ZnO/DMF suspension and magnetic
stirred at 50oC for 3h. PAN/ZnO suspensions were prepared
with the composition presented in the table I .

TABLE I
PAN/ZnO SUSPENSIONS COMPOSITIO N
Sample PAN concentration
(% wt) ZnO concentration
(% wt)
PAN7 7 0
PAN7Z0.5 7 0.5
PAN7Z1 7 1
PAN10 10 0
PAN10Z0.5 10 0.5
PAN10Z1 10 1

PAN/ZnO electrospun fibers was obtained with NaBond
equipment using a glass s yringe and a copper plate as the
electrode collector. Electrospinning process parameters for
obtaining composite fibers were the following : applied
voltage of 15kV, solution flow rate of 2.0 ml/h, spinneret -to-
collector distance of 18 cm, nozzle size of 0.8 mm and a
stationary aluminium foil substrate.
D. Characterization
ZnO nanoparticles w ere structural and morphological
characteri zed by X -ray diffraction employing an X -ray
diffractometer (Bruker AXS D8 DISCOVER) , theta -2theta
configuration, with Cu Kα radiation, λ=1.5406 Å and
aLynxEye 1D detector, at scanspeed of 1s/step and a
increment of 0,04° form 10° to 100° (2theta) and employing a
scanning electron microscope (FESEM, Carl Zeiss Auriga) at
an accelerating voltage of 3 kV at a 50k X magnificat ion.
Morphological characterization of the PAN/ZnO fibers
using scanning electron microscopy (SEM) was performed by
a FESEM/FIB/EDS Workstation Auriga, with an acceleration
voltage of 2 kV, using the SESI detector. Optical
characterization of the polyacry lonitrile -based electrospun
fibers by spectrophotometry was recorded in the wavelength
range of 200 -400 nm using a double beam UV -VIS
spectrophotometer ( UV-VIS Spectrophotometer 570 Jasco) .

III. RESULTS AND DISCUSSION
In this study, chemical method synthesis i s optimized for
suitable temperature in order to obtain zinc oxide
nanoparticles using ZnCl 2 and NaOH as precursors [ 8].
Synthesis at dif ferent temperatures 80OC, 85OC and 90OC led
to obtaining zinc hydroxide Zn(OH) 2, according to the
equation (1) below :
ZnCl 2 + 2 NaOH Zn(OH) 2 + 2NaCl (1)
During the decomposing process (400oC for 1h), Zn(OH) 2
is completely converted into ZnO fol low by equation (2):
Zn(OH) 2 ZnO + H 2O (2)
ZnO nanoparticles was structural and m orphological
characterised to confirm the suitable temperature for obtained
a high purity, shape and dimension uniformity, the necessary prope rties for filler material used in polymer solution for
electrospinning process.

Fig. 1. XRD pattern for ZnO nanoparticles.

Fig. 1 show s X-ray diffraction of ZnO nanoparticles co –
precipitation synthesized at different temperature 80oC, 85oC
and 90oC. All samples presented specific peaks for ZnO at
scattering angles (2θ) of 31.36o, 34.02o, 35.85o, 47.16o,
56.25o, 62.53o, 67.63o and 68.79o correspond ing to the
reflection from: (100), (002), (101), (102), (110), (103),
(200), and (112) crystal lographic planes, respectively. It also
shows that the pa rticle has a hexagonal phase (wurtzite
structure), with space group P63mc and with lattice constants
a = b = 3.2492 Å, c = 5.20661. ZnO obtained have a higher
purity, confirmed by the absence of diffraction peak for any
precursors or impurity phase such as Zn(OH) 2. Increasing the
temperature between 80oC and 90oC during the chemical
synthesis do not effect nanoparticles structural prop erties.
The temperature have an important effect on the size and
shape of ZnO nanoparticles . The average particle size using
SEM data is found to be 38 nm, 125 nm, and 332 nm for the
samples obtained at 80oC, 85oC and 90oC. Sample obtained at
80oC (fig. 2a) consist of monodispersed nanoparticles with
rounded edges . As the temperature is increased to 85oC (fig.
2b) the shape of the particles is changed in polygonal and size
of the particles also increases to 125nm . ZnO particle
synthes is at higher temperature, 90oC (fig.2c) have a round
morphology and a size of 332nm due to the coalesce with one
another to form a larger particle or coagulate.

a

b

c

Fig. 2. SEM imagines for ZnO powder obtained by co -precipitation method
at 80oC (a), 85oC (b) and 90oC (c).

Solution preparation is a very important step in electro –
spinning process because the uniformity, average diamete r
and the absence of the defect of the fibbers depend of the
solution prop erties. For electrospinning PAN/ZnO solution
was used ZnO nanopowder (<60 nm) obtained by co –
precipitation method at 80oC. Solution s with diff erent
composition s (table I ) were used for electrospinning
nanocomposite fibers.

a
d

b
e

c
f

Fig. 3. SEM imag es of the sample s P7 (a), P7Z0.5 (b), P7Z1 (c), P10 (d),
P10Z0.5 (e) and P10Z1 (f).

SEM images (fig. 3) have revealed that the size of the
fibers has been affected by the concentration of polymer
matrix and by the filler material. All electrospun solution s
conducted to homogeneous nanofibers without formation of aggregates, indicating a n uniform dispensation of ZnO in
PAN polymer solution.

0.0 0.5 1.00100200300400500600
Diameter of fiber (nm)
Concentration ZnO (% weght)P7P10

Fig. 4. Diameter of the fibers as a function of ZnO concentration

The average diameter of the composite fibers as a function
of ZnO concentration has been shown in figure 4. In the case
of electrospinning of polymer solutions with a concentration
of 7% P AN ( fig.3a ) and 10% PAN ( fig.3c ) without filler
material, the resulting fiber diameters increase with polymer
solution concentration up to 14- 60 nm and 113 -239 nm
respectively . The addition of ZnO in 0.5% ( fig. 3b) and 1%
wt (fig. 3c) concentration to 7% PAN solution leads to an
increas ing in the fibers diameter in the range of 50-75 nm and
77-152 nm respectively. The effect of the addition of ZnO in
the same concentrations to the 10% PAN polymer solution on
the fiber diameters was more pronounced. Thus, the resulted
fiber reached diameters between 287-359 nm and 560 -600 nm
respectively.

Fig. 5. UV transmission spectra of the PAN composite fibrous membrane
containing different concentration of ZnO

UV shielding property of the fibrous composite membra ne
of PAN/ZnO were studied by optical transmittance
measurements. For analyse the effect of ZnO concentration
on UV shielding properties of the membrane, PAN has been
considered the reference material. The UV transmittance
spectra (UV -B (280 -315) and UV -A (315-400)) of PAN with
different concentration of ZnO have been shown in figure 5.
It has been observed that the fibrous membrane obtained
for higher concentration of PAN (sample P10 ) has low
transparency for both UVA and UVB radiations, with similar
0.0 0.5 1.00123456

P10-UV-BP10-UV-AP7-UV-BT (%)
Concentration ZnO (% weght)P7-UV-A

value 0.83% and 0.63% respectively. In the case of sample P7
(lower concentration of PAN) the transparency it is higher for
UVA radiations 5.68% and decreasing to 2.73% for UVB
radiation. The UV shielding efficiency was improve d by the
presences of ZnO. In the case of fiber produced from higher
concentration polymer samples (P10), the addition of ZnO
produce a small decrees in the UV shielding property ;
transparency was reduced to value 0.22% for both UVA and
UVB. In case of samples P7 , the presence of ZnO condu cted
to an important improvement of the UV shielding by 0.12%
transparency deacreasing . The UV shielding efficiency has
been increased due to the presence of ZnO who is acting as a
physical filter against the UV -B and particularly UV -A
radiation of the sun .

IV. CONCLUSIONS
In this paper the influence of processing temperature on the
ZnO nanoparticles structural and morphological properties
was stud ied. The increasing of the temperature ha d no effect
on structural properties but have a strong influence on the
shape and size of the nanoparticles.
The UV shielding properties of the PAN/ZnO fibrous
composite membranes have been studied and analyzed. Two
type of PAN/ZnO membrane have been obtained and ZnO
concentration effect on shielding properties have been
syste matically studied. It has been found that derived
PAN/ZnO with 1% concentration exhibited excellent UV
filtering in both the UV -A and UV -B ranges.

ACKNO WLEDGMENT

This work was supported by the CORE Programme, project
number PN 16 11 02 05 / 2016 and Romania – JINR Dubna
Scientific Bilateral Cooperation Programme: “ ZnO complex
multilayer system – deposition and investigation ”.

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