European Journal of Scientific Research
ISSN 1450-216X Vol.57 No.4 (2011), pp.583-591
© EuroJournals Publishing, Inc. 2011
http://www.eurojournals.com/ejsr.htm
Study of Optical and Mechanical Properties for
(PVA-AgCO3) Composites
Bahaa H. Rabee
Department of physics, College of Education
Babylon University, Iraq
E-mail: dr_bahaa 19@yahoo.com
Abstract
In this research, samples of pure poly vinyl alcohol and poly vinyl alcohol doped
with silver carbonate were prepared using casting technique. The PVA samples with
AgCO3 additive prepared with different percentages(0,1,2,4 and 5) wt.% and different
thickness. The experimental results showed that the absorption coefficient increases and
energy gap of the indirect allowed and forbidden decreases with increase the weight
percentage of silver carbonate, the extinction coefficient increases with increase the silver
carbonate content. The mechanical properties(Velocity of Ultrasonic wave, Specific
Acoustic Impedance, Bulk Modulus and Compressibility change with increase the
concentration of silver carbonate
Keywords: poly vinyl alcohol, optical properties, composite.
1. Introduction
Composites containing two materials with die rent physical properties exhibit often new properties
.The composites can provide improved characteristics not obtain able by any of the original
components alone an dare used in a wide variety of industrial products[Kalisza G. et al, 2005].
Polymer matrix composites are very popular due to their low cost, high strength to weight ratio, noncorrosive and simple fabrication methods. Polymer matrix composites reinforcement by strong fibrous
network is characterized by the high tensile strength, high stiffness, high fracture toughness, good
abrasion resistance, good puncture resistance, good corrosion resistance and low cost. A variety of
additives are used in the composites to improve the material properties, aesthetics, manufacturing
process, and performance. The additives can be divided into three groups -- catalysts, promoters, and
inhibitors; coloring dyes; and, releasing agents[KUMAR A.,2008]. In general the interaction of
electromagnetic radiation (light) with matter is controlled by three properties, the specific conductivity,
the electric conductive capacity and the magnetic inductive capacity. These properties are related to the
refractive index and the absorption index of the medium. Ahmed and Asrar, in(2010) studied the effect
of lithium fluoride content on some optical properties of polystyrene by different volume percentages
from these salts with polymer and by different thickness .The absorption and transmission spectra has
been recorded in the wavelength range (190-1100)nm . The absorption coefficient increases and energy
gap decreases with volume percentage of salts. This paper deals with results of the effect of silver
carbonate on the optical and mechanical properties of poly vinyl alcohol.
Study of Optical and Mechanical Properties for (PVA-AgCO3) Composites
584
2. Experiment
The materials used in the paper is poly vinyl alcohol as matrix and silver carbonate as a filler. The
weight percentages of silver carbonate are (0,1,2,4 and 5)wt.%. films of pure PVA and PVA doped
with silver carbonate were prepared using casting technique thickness ranged between (70-80)µm. The
transmission & absorption spectra of composites have been recording in the length range (190-900)nm
using double-beam spectrophotometer (UV-210oA shimedza ).
The mechanical properties is measured by Ultrasonic Velocity System Measurement.
3. Results and Discussion
Optical absorbance measurements were taken for silver carbonate- poly vinyl alcohol samples to
compare the effect of the filler particles on the optical properties of the composites as shown in
figure(1). If the goal is to obtain a transparent composite, the filler needs to be transparent and the
scattering at the interface between the filler and the matrix needs to be as small as possible to decrease
the absorbance [Laurissa A., 2008]
Figure 1: The relationship between the absorbance and wavelength of the PVA-AgCO3 composites
pure
3.5
1wt.%
2wt.%
3
4wt.%
5wt.%
A b so rb an ce
2.5
2
1.5
1
0.5
0
0
100
200
300
400
500
600
700
800
900
Wavelength(nm)
The absorption coefficient (α) is calculated by using the absorption relation[ Majdi K.
et.al.,1997] :
I = I 0 exp(− ad )
(1)
Hence
A
2
(2)
α = ( 2 . 303 / d ) log(
/
) = ( 2 . 303 / d )[ A + log( 1 −
)] = 2 . 303
..........
I I
R
d
Where : d is the thickness of sample and A is absorbance(A=-log(T) and R is the reflectivity,
while the parameter T is the transmittance.
0
585
Bahaa H. Rabee
Figure 2:
900
p ure
800
1wt .%
2 wt .%
600
4 wt .%
-1
700
a (cm)
5wt .%
500
400
300
200
100
0
0
1
2
3
4
5
6
7
E(eV)
The results showed that the values of absorption coefficient of the PVA-AgCO3 composites less
than 104cm-1 which indicates to the indirect electronic transition. The forbidden energy gap of indirect
transition both allowed, forbidden calculated according to the relationship[Kathalingam et.al. , 2007] :
ahv = A(hv − E g ) m
(2)
Where : hv is the energy of photon , A is proportionality constant and Eg is forbidden energy
gap of the indirect transition.
If the value of (m=2) indicates to allowed indirect transition . when the value (m=3) indicates to
forbidden indirect transition.
200
180
160
140
120
100
80
60
40
20
0
0
0
0
0
0
0
0
0
0
0
(1 )
3000
(ah?)1/2(cm-1.eV)1/2
(ah?)1/2 (cm-1.eV)1/2
Figure 3: The relationship between (αhυ)1/m(cm-1.eV)1/m and photon energy of PVA-AgCO3 composites
(2 )
2500
2000
1500
1000
500
0
0
2
4
6
0
8
2
4
(3 )
8
(4 )
300 0
3 000
ah?)1/2(cm-1.eV)1/2
(ah?)1/2(cm-1.eV)1/2
6
E( e V )
E(e V )
250 0
200 0
150 0
100 0
50 0
2 500
2 000
1 500
1 000
500
0
0
2
4
6
8
0
0
E(e V)
2
4
E(eV )
ah?)1/2(cm-1.eV)1/2
(5 )
2500
2000
1500
1000
500
0
0
2
4
6
8
E ( eV )
A) the relationship between (αhυ)1/2(cm-1.eV)1/2 and photon energy of PVA-AgCO3 composites:
(1) pure (2) 1wt.% AgCO3 (3) 2wt.% AgCO3 (4) 4wt.% AgCO3 (5) 5wt.% AgCO3
6
8
Study of Optical and Mechanical Properties for (PVA-AgCO3) Composites
586
Figure 3: The relationship between (αhυ)1/m(cm-1.eV)1/m and photon energy of PVA-AgCO3 composites continued
1200
(ah?)1/3(cm-1.eV)1/3
(ah?)1/3(cm-1.eV)1/3
1400
(1)
1000
800
600
400
200
0
0
2
4
6
2000
1800
1600
1400
1200
(2)
1000
800
600
400
200
0
0
8
2
4
8
E(eV)
E(eV)
200 0
2000
180 0
160 0
1/3
1000
ah?) (cm .eV)
1500
-1
1/3
(3)
1/3
1/3
-1
(ah?) (cm .eV)
6
500
(4)
140 0
120 0
100 0
80 0
60 0
40 0
20 0
0
0
2
4
6
0
8
0
2
E(eV)
1/3
1800
1/3
-1
(ah?) (cm .eV)
4
6
8
E(eV)
(5)
1600
1400
1200
1000
800
600
400
200
0
0
2
4
6
8
E(eV )
B) the relationship between (αhυ)1/3(cm-1.eV)1/3 and photon energy of PVA-AgCO3 composites:
(1) pure (2) 1wt.% AgCO3 (3) 2wt.% AgCO3 (4) 4wt.% AgCO3 (5) 5wt.% AgCO3
These figures represent the energy gaps for the two indirect transitions. This behavior may
explain the fact that the silver carbonate increased the disorder of these materials. The increasing
degree of disorder causes the band tail to increase, which according to the electronic structure of
amorphous materials, will lead to a decrease of the estimated optical gap[Soliman and Sayed, 2002].
Figure(4) shows the variations of extinction coefficient (k=αλ/4π) with wave length for pure and doped
PVA with silver carbonate . This figure shows that, k value increases with increasing of doping
concentration. The behavior of extinction coefficient (k) can be ascribed according to high absorption
coefficient. This result indicates that the doping atoms of silver carbonate will modify the structure of
587
Bahaa H. Rabee
the host polymer. An interesting result is silver carbonate doping increases the absorbance in the
visible region[Ahmed R.,2008].
Figure 4: The relationship between the extinction coefficient (k) and wave length(λ) of the PVA-AgCO3
composites
3.0E-03
pure
1wt.%
2wt .%
2.5E-03
4wt .%
5wt.%
K
2.0E-03
1.5E-03
1.0E-03
5.0E-04
0.0E+00
0
100
200
300
400
500
600
700
800
900
wavelength(nm)
The variation of the refractive index( for PVA-AgCO3 composites for various different
concentration a a function of wavelength at 30oC is shown in figure (5). The figure shows that the
refractive index increase as a result of filler addition, this behaviour can be attributed to the increasing
of the packing density as a result of filler content.
Figure 5: The relationship between the refractive index (n) and wave length(λ) of the PVA-AgCO3 composites
9
pure
1wt.%
8
2wt.%
7
4wt.%
5wt.%
6
n
5
4
3
2
1
0
0
100
200
300
400
500
600
Wavelengh(nm)
700
800
900
Study of Optical and Mechanical Properties for (PVA-AgCO3) Composites
588
The refractive index also shows a decreasing region in the λ range(350-450)nm which is
analogous to valley results from high absorbance of AgCO3 atoms which take place in this wavelength
range.
The real and imaginary parts of dielectric constants( ε1 =n2-k2and ε2=2nk) of pure and doped
PVA with AgCO3 with different concentrations are depending on λ are shown in Figs(6 ,7) [Ahmed
R.,2008].
Figure 6: The relationship between the real part of dielectric constant and wave length(λ) of the PVA-AgCO3
composites
It is concluded that the variation of ε1 mainly depends on (n2) because of small values of (k2),
while ε2 mainly depends on the (k) values which are related to the variation of absorption coefficients.
Figure 7: The relationship between the imaginary part of dielectric constant and wave length(λ) of the PVAAgCO3 composites
589
Bahaa H. Rabee
Figures(8,9,10,11) show the variation the velocity of Ultrasonic wave(V), Specific Acoustic
Impedance (Z= ρV where ρ is density ), Compressibility(
B = (ρ V
2
) −1
−1
2
and Bulk Modulus( k = B = ρV ) with concentration of silver carbonate respectively, using the
thickness of sample and delay time was calculate velocity of Ultrasonic wave.
Figure 8: The relationship between the velocity of Ultrasonic wave and the concentration of silver carbonate
of PVA-AgCO3 composites
3
V(m/Sec)
2.5
2
1.5
1
0.5
0
0
1
2
3
4
5
Con. of AgCO3 wt.%
Figure 9: The relationship between the Specific Acoustic Impedance and the concentration of silver carbonate
of PVA-AgCO3 composites
6000
5000
Z
4000
3000
2000
1000
0
0
1
2
3
Con. of AgCO3 w t.%
4
5
Study of Optical and Mechanical Properties for (PVA-AgCO3) Composites
590
Figure 10: The relationship between the Compressibility and the concentration of silver carbonate of PVAAgCO3 composites
8.1E-04
7.1E-04
6.1E-04
5.1E-04
B
4.1E-04
3.1E-04
2.1E-04
1.1E-04
1.0E-05
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Con. of AgCO3 wt.%
Figure 11: The relationship between the Bulk Modulus and the concentration of silver carbonate of PVAAgCO3 composites
16000
14000
12000
K
10000
8000
6000
4000
2000
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Con. of AgCO3 wt.%
These figures show that, the velocity of Ultrasonic wave increases with increasing the
concentration of silver carbonate, this attributed to silver carbonate particles could act as medium to
travel the waves. Consequently, Specific Acoustic Impedance and Bulk Modulus are increasing and
Compressibility decreases with increase the concentration of silver carbonate[Al-Bermany et al, 2002].
Conclusions
a. The absorption coefficient is increasing with increasing of the filler wt.% content.
591
Bahaa H. Rabee
b. The experimental results showed that the absorption coefficient less than 104cm-1 this is
indicates to forbidden and allowed indirect electronic transitions.
c. The forbidden energy gap is decreasing with increasing of the filler wt.% content
d. The velocity of Ultrasonic wave, Specific Acoustic Impedance and Bulk Modulus are
increasing and Compressibility decreases with increase the concentration of silver carbonate
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