تأثيراوكسيد التيتانيوم الثنائي النانوي على الخصائص البصرية لأغشية بولي فينايل كلورايد المحتوية علىحلقة الترايزول

Abstract

Abstract Optical properties of pure and dopedpoly(vinyl chloride) PVCcontaina triazole ring (P),with different concentration of nanotitanium oxide (TiO2)were studied. The films prepared by using casting technique.Spectrums of transmission and absorption was used to study all optical Parameters.Different parameters such as absorption coefficient, refractive index, extinction coefficient and energy gap were studied in the spectral range (200-800)nm. This study reveals that the optical properties of (PVC)containtriazole ring affect by the doping of (TiO2) where The transmission and energy gap value decreases with increasing percentage where the energy gapdecreases from (5.79 to 3.24 )EV.Absorption coefficient,refractive index and extinction coefficient were increased with the increase of (TiO2)concentration.

Keywords:- PVC polymer، Nano TiO2، Optical properties.

Introduction Polymeric materials have attracted many of scientific and technological researchers, due to their wide industrial applications. In recent years, polymer-nanocomposite and understanding their physical and chemical properties have attracted great attention [1,2].The presence of nanoparticles in polymer improves the mechanical, electrical and optical properties of the materials [3],Polyvinyl chloride (PVC) is one of the earliest and best known polymers. PVC was seen as a replacement for glass in a variety of applications and is currently used extensively in glazing applications.In recent times, PVC has received much attention and is being exploited as a polymer host. PVC is a commercially available, inexpensive polymer and is compatible with plasticizers such as dibutyl phthalate (DBP), dioctyladipate (DOA), dioctyl phthalate (DOP), polycarbonate (PC) and ethylene carbonate (EC). Various )PVC( based systems have been found to form electrolytes with conductivities ranging from )10-8 to 10-3(S.cm-1 at room temperature. The electrical and optical properties of polymers can be suitably modified by the addition of dopants depending on their reactivity with the host matrix [4]. Recently, optical properties of solvent cast polymer have received considerable attention [5]. The optical propertiesof Poly vinyl chloride doped with different concentration of nanosize zinc oxide ZnO(1-20)wt% [6]. The effect of continues )Co2( laser radiation on the optical properties of pure Poly Vinyl Chloride and doped of )ZnO( nanoparticles has been investigated [7]. Electrical conductivity of polyaniline doped PVC–PMMA polymer blend[8]. Dielectric properties of Carbon Black /PVC (cement) composites [9]. The aim of this work is to investigate the optical properties of )PVC( contains triazolering and )PVC( films with different concentration of Nano )TiO2(.

Experimental Poly(vinyl chloride) contains triazoleringwas prepared by the method previously described by Ahmed [10] as in Figure below:

PVC contains a triazole ring (P), doped with (nano TiO2). The (P) films with different weights (0.5, 0.10, 0.20) wt% were prepared by dissolving )P( and (nano TiO2) in )THF( with stirring the solution, using a magnetic stirrer for about (30 min) at room temperature for complete dissolving. The solution was poured into a clean glass plate and kept till dried (3days) at room temperature. The thickness of the produced films was (72µm).

Results and discussion The UV–VIS transmittance spectrum in the region (200-800)nm for doped and undoped films samples (a, b, c and d) are shown in Figure (1). In this figure the transmittance was increased with the increase of wavelength for all films, while after doping it can be noticed that the transmittance is decreases with increasing )TiO2(concentration.

Figure (1): The transmission spectra of )TiO2( doped )PVC( films as function of wavelength at different concentrations. The absorption coefficient (α) can be calculated using the following relation [12] α = (2.303 * A) / t ………. (1) Where (A) is the absorption and (t) is the film thickness. Figure (2) shows the dependence of the absorption coefficient (α) on the wavelength. It is clear from this figure that a decreasing behavior for the absorption coefficient with increasing of the wavelength for all samples (a-d) is take place. In contrast the absorption coefficient increases with increasing the doping concentration of (TiO2)this increasing may be attributed to the difference in carrier concentration or could be related to the existence of more transmissions from higher vibration levels of the ground state to higher sublevels of the first excited singlet state.

Figure (2): Variation the Absorption coefficient as a function of wavelength. The refractive index(n) is an important parameter for optical materials and applications. Thus, it is important to determine optical constants of the films and the complex optical refractive index. The refractive index of the films has been determined from the Reflectance (R) , Figure (3) shows the variation of the refractive index with wavelength for all samples. The refractive index shows an increasein the wavelength range (200-410) name for all(PVC) samples while for samples with different concentration,it shows a noticeable decreased withother wavelengths. The refractive index was increased with the increase of (TiO2)concentrations (b, c and d) respectively.

Figure (3): Variation the refractive index as a function of wavelength.

The dependence of the extinction coefficient (k) on the wavelength in the range (200-800) nm of pure and doped samples is shown in Figure (4). It is clear that the extinction coefficient decreases with increasing wavelength for all samples before and after doped of (TiO2) . Extinction coefficient was increased for (PVC) films with increasing the doping concentration (b, c and d) this is due to the increase in absorption coefficient, where the extinction coefficient depending on the absorption coefficient by the equation.

K=αλ/4π …………(2)

Figure (4): Variation the extinction coefficient as a function of wavelength.

According to the inter-band absorption theory, the optical band of the films can be calculated using Tauc's relation [23]:- (αhυ)p = A(hυ–Eg) ………….(3) where (α) is the absorption coefficient, (A) a constant, (h) is Planck's constant, (υ) the photon frequency, (Eg)is the optical band gap and (p) is an index which could take different values according to the electronic transition. The experimental data were fitted to the theoretical Eq (3) for different values of (p) and the best fit was obtained for p=2 this behavior directed that the transitions are allowed direct transitions. The direct allowed band gap was determined by plotting (αhν)2 as function of photon energy (E) for samples (a, b, c, d) are shown in figures (5 to8) respectively, the graph is a straight line and the value of (Eg)is obtained by extrapolating the linear portion of the graph to intercept the photon energy axis [24]. It was found that (Eg) reduces from (5.79eV) of pure sample to (5.1,4.05 and3.24)eV for samples (b, c and d) respectively. Showing the values of direct allowed gap is mentioned in Table (1).

Table (1):The optical energy gap of pure and doped (PVC)contains triazolering(P)films.

Sample P+%Nano Eg(eV) a P 5.79 b P+0.05 5.1 c P+0.1 4.05 d P+0.2 3.24

Figure (5):Variation the (αhν)2 as a function of photon energy for (a) film.

Figure (6): Variation the (αhν)2 as a function of photon energy for (b) film.

Conclusions The results indicate that (TiO2)can effectively dope (PVC)contains triazole ring and enhance its optical properties. The increase of (TiO2)concentration leads to decrease the transmission. The optical parameters such as absorption coefficient,refractive index and extinction coefficient were increased with the increase of (TiO2)concentration. Energy gap valuesshows dependence on (TiO2)concentration where decreased with increase percentage from (5.79 to 3.24) eV.

References 1- GodovskyD. Y., Device Applications of Polymer-Nano composites, adv. Polym.sci., 153, 163-205, 2000. 2- Kasim F. A., Mahdi M. A., Hasan J. J., Al-Ani S.K.J., KasimS. J., Preparation and optical properties of CdS/Epoxy nanocomposite, Int. J. Nano electronics and Materials., 5, 57-66, 2012. 3- Tachikawa Sh., Noguchi A., TsugeT., HaraM., Odawara O., Wada H., Optical Properties of ZnO Nanoparticles Capped with Polymers, Materials., 4, 1132-1143, 2011. 4- Chandra S.P., Naveen K.P., Sasikala.U., Rao V.V.R.N and SharmaA.K., Investigations on lithium ion complexed polyvinyl chloride (PVC) solid polymer electrolyte films, IRACST – Engineering Science and Technology: An International Journal (ESTIJ)., 2(5), 21, ISSN: 2250-3498, 2012. 5- Sharaf F., El-Eraki M.H.I., El-Gohary A.R., Ahmed F.M.A., The optical and mechanical properties before and after gamma irradiation of poly(viny1 alcohol) films doped with lead acetate, Polymer Degradation and Stability., 47, 343-348, 1995. 6- Al-Taa'y W.A., Ameer A.A., Wedad H.D., Mustafa A., Youif E.,optical constants of poly vinychlorid doped by nanoZnO,Journal of chemical and pharmaceutical research., 7(8), 536-541, 2015. 7- Hamad T.K., Rahimi M.Y.,Al-Taa'y W.A., Bashar M.A., Youif E.,CO2 Laser enhanced Modification of the Optical properties of Nano -ZnO doped PVC films, International Journal of polymererscience., Volume 2014, Article ID 787595, 8pages, 2014. 8- Deshmukh S.H., Burghate D.K., Akhare V.P., Deogaonkar V.S., Deshmukh P.T.,Deshmukh M.S., Bull. Mater. Sci., 30, 51–56, 2007. 9- Shemaa H.J and Waleed A.H.,Journal of Basrah Researches ((Sciences)).,ISSN- 1817 -2695, 38, 60-71, 2012. 10- Ahmed A., Journal of Al-Nahrain University.,18 (1), 66-73, 2015.

الخلاصة درست الخصائص البصرية لأغشية بولي فينايلكلورايد النقية PVC)) المحتوية على حلقة الترايزول والمشوبة بمادةاوكسيد التيتانيوم الثنائيالنانوي ( (TiO2 بعد تحضيرها بأستخدام طريقة الصب وبنسب تشويب مختلفة.اطياف الانبعاثية والامتصاصية استخدمت لدراسة المعلمات البصرية المختلفة. تم دراسة المعلمات البصرية المتمثلة بمعامل الامتصاص، معامل الأنكسار، معامل الخمود وفجوة الطاقة ضمن مدى الاطوال الموجية nm(800-200). توصلنا في هذه الدراسة الى اناضافة اوكسيد التيتانيوم الثنائي في بولي فينايلكلورايد ادى الى انخفاض في كل من الانبعاثية وفجوة الطاقة والتي انخفضت من 5.79) eV الى 3.24) بينما زاد كل من معامل الامتصاص ، معامل الأنكسارو معامل الخمود مع زيادة هذه النسب.