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  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
  Optical properties of (pva cr cl2) composites
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Optical properties of (pva cr cl2) composites

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International peer-reviewed academic journals call for papers, http://www.iiste.org/Journals …

International peer-reviewed academic journals call for papers, http://www.iiste.org/Journals

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  • 1. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 59 Optical Properties of (PVA-CrCl2) Composites ( 1) Ahmed Hashim ,( 2) Amjed Marza,(3) Bahaa H. Rabee ,(4) Majeed Ali Habeeb, (5) Nahida Abd-alkadhim, (6) Athraa Saad (1,3,4) Babylon University, College of Education , Department of physics, Iraq. (2,6) Babylon University, College of Science , Department of chemistry, Iraq. (5) Babylon University, Enjineering Affairs, Iraq. E-Mail: ahmed_taay@yahoo.com Abstract The purpose of this paper, study the effect of addition Krum chloride on optical properties of polyvinyl-alcohol . The composites prepare by casting technique with different weight percentages of CrCl2 are (0,1,2,3). Results showed that the absorbance increases with increase the concentration of CrCl2, absorption coefficient, extinction coefficient, refractive index and real and imaginary parts of dielectric constants are increasing with increase CrCl2 concentration. keywords: Polyvinyl alcohol, Optical Properties, Composites. Introduction Optical properties of polymers constitute an important aspects in study of electronic transition and the possibility of their application as optical filters, a cover in solar collection, selection surfaces and green house. The information about the electronic structure of crystalline and amorphous semiconductors has been mostly accumulated from the studies of optical properties in wide frequency range. The significance of amorphous semiconductors is in its energy gap[1]. The typical advantages of organic polymers are flexibility, toughness, formability, and low density, whereas ceramics have excellent mechanical, thermal, and optical properties, such as surface hardness, modulus, strength, heat resistance, and high refractive index. The combination of organic polymers and ceramics promises new hybrid materials with high performance. Numerous technological applications have been identified for these composite materials, such as electromagnetic and radio frequency interference shielding for electronic devices (for example, computer and cellular housings), over-current protection devices, photothermal optical recording, and direction-finding antennas[2]. Experimental work The materials used in this work are polyvinyl alcohol and CrCl2. The weight percentages of CrCl2 are ( 0,1,2 and 3) wt.%. The casting technique is used to prepare the samples with thickness ranged between (350- 475)µm. The transmission and absorption spectra of PVA-CrCl2 composites have been recording in the length range (200-800) nm using double-beam spectrophotometer (UV-210o A shimedza ). Results and Discussion Figure(1) shows the variation of the optical absorbance with the wavelength of the incident light for (PVA- CrCl2) composites. 0 0.5 1 1.5 2 2.5 3 3.5 4 200 300 400 500 600 700 800 Wavelength(nm) Absorbance pure 1wt.% 2 wt.% 3 wt.% FIG.1 Variation of Optical absorbance for (PVA-CrCl2) composite with wavelength
  • 2. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 60 The figure indicate that the absorbance increases with increase of CrCl2 concentration, this attributed to the high absorbance of CrCl2. The variation of the absorption coefficient, α, as a function photon energy are presented in figure(2) . It was calculated from equation[3]: …………………………………(1) Where : A is absorbance and d is the thickness of sample The values of the absorption coefficient are less than 104 cm–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 relation between the absorption coefficient, α, and the incident photon energy, hν, can be written as[4] : (αhν)n =B(hν −Eg) …………………………………(2) where B is an constant depending on the transition probability and n is an index that characterizes the optical absorption process and is theoretically equal to 1/2,2, 1/3 or 2/3 for indirect allowed, direct allowed, indirect forbidden and direct forbidden transition, respectively. The usual method to calculate the band gap energy is to plot a graph between (αhν)n and photon energy, hν, and find the value of the n which gives the best linear graph. This value of n decides the nature of the energy gap or transition involved. If an appropriate value of n is used to obtain linear plot, the value of Eg will be given by intercept on the hν-axis as shown in figures(3,4). 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 1 2 3 4 5 6 7 Photon energy(eV) pure 1wt.% 2 wt.% 3 wt.% FIG.2 absorption coefficient for (PVA-CrCl2) composite with various photon energy α(cm)-1 .303.2 d A =α
  • 3. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 61 The attenuation coefficient (k) is directly proportional to the absorption coefficient(α):[4] k=αλ/4π …………………………(3) Where λ is the free space wavelength of light. 0 2 4 6 8 10 12 14 0 1 2 3 4 5 6 7 Photon energy(eV) pure 1wt.% 2 wt.% 3 wt.% FIG.3 the relationship between (αhυ)1/2 (cm-1.eV)1/2 and photon energy of (PVA-CrCl2) composites. (αhυ) 1/2 (cm -1 .eV) 1/2 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 Photon energy(eV) pure 1wt.% 2 wt.% 3 wt.% (αhυ)1/3 (cm-1 .eV)1/3 FIG.4 the relationship between (αhυ)1/3 (cm-1 .eV)1/3 and photon energy of (PVA-CrCl2) composites.
  • 4. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 62 Figure(6) shows the variation of the refractive index ( R R n − + = 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 CrCl2 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[4]. 0.0E+00 1.0E-06 2.0E-06 3.0E-06 4.0E-06 5.0E-06 6.0E-06 7.0E-06 8.0E-06 200 300 400 500 600 700 800 k pure 1wt.% 2 wt.% 3 wt.% λ(nm) FIG.5 extinction coefficient for (PVA-CrCl2) composite with various photon energy 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 0 1 2 3 4 5 6 7 photon energy(eV) n pure 1wt.% 2 wt.% 3 wt.% FIG.6 the relationship between refractive index for (PVA-CrCl2) composite with photon energy
  • 5. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 63 Figures(7,8) show the variation of real and imaginary parts of dielectric constants (ε1 =n2 -k2 and ε2=2nk) of (PVA- CrCl2) 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[5]. Conclusions 1. The absorbance increases with increase the weight percentages of CrCl2. 2. The absorption coefficient, extinction coefficient, refractive index and real and imaginary parts of dielectric constants are increasing with increase of CrCl2 concentration. 3. The forbidden energy gap decreases with increase of CrCl2 concentration. References [1] Gabriel Pinto and Abdel-Karim Maaroufi, 2011, "Critical filler concentration for electroconductive polymer composites", Society of Plastics Engineers (SPE), 10.1002/spepro.003521. [2] JAE-WAN KIM, WON-JEI CHO, CHANG-SIK HA, 2002, " Morphology, Crystalline Structure, and Properties of Poly(vinylidene fluoride)/Silica Hybrid Composites, J. of Polymer Science: Part B: Polymer Physics,Vol.40, PP.(19–30). 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 photon energy(eV) pure 1wt.% 2 wt.% 3 wt.%ε1 FIG.7 variation of real part of dielectric constant (PVA-CrCl2) composite with photon energy 0.E+00 5.E-06 1.E-05 2.E-05 2.E-05 3.E-05 3.E-05 4.E-05 4.E-05 5.E-05 0 1 2 3 4 5 6 7 photon energy(eV) pure 1wt.% 2 wt.% 3 wt.% ε2 FIG.8 variation of imaginary part of dielectric constant(PVA-CrCl2) composite with photon energy
  • 6. Chemistry and Materials Research www.iiste.org ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online) Vol.3 No.7, 2013 64 [3] Hutagalwng. S. D. and Lee. B. Y. ,2007, Proceeding of the 2nd international conference Nano/Micro Engineered and Molecular systems, January, Bangkok,Thailand. [4] NICOLAE ÞIGÃU, 2008, " STRUCTURAL CHARACTERIZATION AND OPTICAL PROPERTIESOF ANNEALED Sb2S3 THIN FILMS", Rom. Journ. Phys., Vol. 53, Nos. 1–2, P. 209–215, Bucharest. [5] Ahmed R.m. , 2008, "Optical study on poly(methyl methacrylate)/poly(vinyl acetate)", Zagazig Uni., Zagazig, Egypt, E-mail-rania 8_7@hotmail. com.
  • 7. This academic article was published by The International Institute for Science, Technology and Education (IISTE). The IISTE is a pioneer in the Open Access Publishing service based in the U.S. and Europe. The aim of the institute is Accelerating Global Knowledge Sharing. More information about the publisher can be found in the IISTE’s homepage: http://www.iiste.org CALL FOR PAPERS The IISTE is currently hosting more than 30 peer-reviewed academic journals and collaborating with academic institutions around the world. There’s no deadline for submission. Prospective authors of IISTE journals can find the submission instruction on the following page: http://www.iiste.org/Journals/ The IISTE editorial team promises to the review and publish all the qualified submissions in a fast manner. All the journals articles are available online to the readers all over the world without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. Printed version of the journals is also available upon request of readers and authors. IISTE Knowledge Sharing Partners EBSCO, Index Copernicus, Ulrich's Periodicals Directory, JournalTOCS, PKP Open Archives Harvester, Bielefeld Academic Search Engine, Elektronische Zeitschriftenbibliothek EZB, Open J-Gate, OCLC WorldCat, Universe Digtial Library , NewJour, Google Scholar

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