merican Journal of Scientific Research
ISSN 2301-2005 Issue 76 September, 2012, pp.5-9
© EuroJournals Publishing, Inc. 2012
http://www.eurojournals.com/ajsr.htm
Study of Optical Properties of (PVA-BaSO4.5H2O) Composites
Ziyyad S. Ahmed
Ministry of Science and Technology, Center of Ceramic
Ahmed Hashim
Babylon University, College of Education e
Department of physics, Iraq
E-Mail: ahmed_taay@yahoo.com
Bahaa H. Rabee
Babylon University, College of Education e
Department of physics, Iraq
Alaa Jewad
Babylon University, College of Agriculture
Department of Soil and Water, Iraq
Abstract
Composites consisting of an polyvinyl alcohol matrix and BaSO4.5H2O as a filler
are designed. The optical properties were measured in the wavelength range from (190-
850) nm. The experimental results showed that the absorption coefficient, extinction
coefficient, refractive index and real and imaginary parts of dielectric constants are
increasing with increase the addition of BaSO4.5H2O content.
Keywords: Polyvinyl alcohol, Optical constants, Composites.
Introduction
The physical properties of polymers may be affected by doping, the certain structural, mechanical,
optical, electrical and magnetic properties of the selected polymer can be controllably modified owing
to the type of the doping, concentration, and the way in which it penetrates and interacts with the
chains of the polymer. Detailed studies of doped polymer with different dopant concentrations allow
the possibility of choice of the desired properties[1]. Polyvinyl alcohol (PVA) is a polymer with
several interesting physical properties, which are very useful in technical applications. PVA, as semi
crystalline material, exhibits certain physical properties resulting from the crystal-amorphous
interfacial effect[2]. Ahmed Hashim et al, 2011, studied the optical properties of the PVA- Al2O3
composites. Results show that the absorption coefficient, extinction coefficient, refractive index and
real and imaginary parts of dielectric constants are increasing with increase Al2O3 concentrations [3].
This paper deals with results of the effect of BaSO4.5H2O on the optical properties of poly vinyl
alcohol.
Study of Optical Properties of (PVA-BaSO4.5H2O) Composites 6
Experimental Work
The materials used in this work are polyvinyl alcohol and BaSO4.5H2O. The weight percentages of
BaSO4.5H2O are (0,3,6 and 9) wt.%. The casting technique is used to prepare the samples with
thickness ranged between (71-86)?m.
The transmission and absorption spectra of PVA- BaSO4.5H2O composites have been recording
in the length range (190-850) nm using double-beam spectrophotometer (UV-210oA shimedza ).
Results and Discussion
Figure(1) shows the variation of the optical absorbance with the wavelength of the incident light for
(PVA- BaSO4.5H2O) composites.
Figure 1: Optical Absorbance for (PVA-BaSO4.5H2O) composite with various wavelength
The figure indicate that the absorbance increases with increase of BaSO4.5H2O concentration,
this attributed to the high absorbance of BaSO4.5H2O.
The variation of the absorption coefficient, ?, as a function photon energy are presented in Fig. 2. It was
calculated from equation[4]:
2.303 .
d
? ? A (1)
Where: A is absorbance and d is the thickness of sample
Figure 2: Variation of absorption coefficient for (PVA-BaSO4.5H2O) composite with photon energy
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7
Photon energy(eV)
pure
3 wt.%
6 wt.%
9 wt.%
?(cm) 1
7 Ziyyad S. Ahmed, Ahmed Hashim, Bahaa H. Rabee, and Alaa Jewad
The values of the absorption coefficient are less than 104cm–1 in the investigation spectral
range. The fundamental absorption, which corresponds to electron excitation from the valence band to
conduction band, can be used to determine the nature and value of the optical band gap, Eg.
The attenuation coefficient (k) is directly proportional to the absorption coefficient (?):
k=??/4? (3)
Where ? is the free space wavelength of light.
Figure 3: Extinction coefficient for (PVA-BaSO4.5H2O) composite with various photon energy
0.0 E+00
5.0 E-06
1.0 E-05
1.5 E-05
2.0 E-05
2.5 E-05
0 100 200 300 400 500 600 700 800 900
k
pure
3 wt.%
6 wt.%
9 wt.%
?(nm)
Figure (4) shows the variation of the refractive index (
R
n R
?
?
?
1
1 ) of composites a function of
photon energy. It has been found that the value of refractive index increases with increasing the
concentration of BaSO4.5H2O which is a result of increasing the number of atomic refractions due to
the increase of the linear polarizability in agreement with Lorentz - Lorentz formula.
Figure 4: Variation refractive index for (PVA-BaSO4.5H2O) composite with various photon energy
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6 7
photon energy(eV)
n
pure
3 wt.%
6 wt.%
9 wt.%
Figures (5,6) show the variation of real and imaginary parts of dielectric constants (?1 =n2-k2and
?2=2nk) of (PVA-BaSO4.5H2O) composites .It is concluded that the variation of ?1 mainly depends on
Study of Optical Properties of (PVA-BaSO4.5H2O) Composites 8
(n2) because of small values of (k2), while ?2 mainly depends on the (k) values which are related to the
variation of absorption coefficients[6].
Figure 5: Variation of real part of dielectric constant (PVA-BaSO4.5H2O) composite with photon energy
0
1
2
3
4
5
6
7
8
9
0 1 2 3 4 5 6 7
photon energy(eV)
pure
3 wt.%
6 wt.%
9 wt.%
?1
Figure 6: Variation of imaginary part of dielectric constant (PVA-BaSO4.5H2O) composite with photon energy
0.E+00
2.E-05
4.E-05
6.E-05
8.E-05
1.E-04
1.E-04
1.E-04
0 1 2 3 4 5 6 7
photon energy(eV)
pure
3 wt.%
6 wt.%
9 wt.%
?2
Conclusions
1. The absorbance increases with increase the weight percentages of BaSO4.5H2O.
2. The absorption coefficient, extinction coefficient, refractive index and real and imaginary parts
of dielectric constants are increasing with increase the weight percentages of BaSO4.5H2O
References
[1] Omed Ghareb and Sarkawt Abubakr, 2010, " Variation of Optical Band Gap Width of PVA
films Doped with Aluminum Iodide", International Conference on Manufacturing Science and
Technology (ICMST 2010), PP.(55).
9 Ziyyad S. Ahmed, Ahmed Hashim, Bahaa H. Rabee, and Alaa Jewad
[2] M. Abdelaziz and E.M. Abdelrazek, 2006," Effect of dopant mixture on structural, optical and
electron spin resonance properties of polyvinyl alcohol", J. of Physica B,
10.1016/j.physb.2006.07.067
[3] Ahmed Hashim, Hamed I. Aboud, Z.AL-Ramadhan and Kaydaa jabair, 2011, The Effect of
Alumina on Some Optical Properties For (PVA- Al2O3) Composites", Proceedings of the 18th
Scientific Conference of College of Education / Al- Mustansirya University, April, Iraq.
[4] Hutagalwng. S. D. and Lee. B. Y. ,2007, Proceeding of the 2nd international conference
Nano/Micro Engineered and Molecular systems, January, Bangkok, Thailand.
[5] NICOLAE ?IG?U, 2008, "STRUCTURAL CHARACTERIZATION AND OPTICAL
PROPERTIES OF ANNEALED Sb2S3 THIN FILMS", Rom. Journ. Phys., Vol. 53, Nos. 1–2,
P. 209–215, Bucharest.
[6] Ahmed R.m. , 2008, "Optical study on poly (methyl methacrylate)/poly (vinyl acetate)",
Zagazig Uni., Zagazig, Egypt, E-mail-rania 8_7@hotmail. com