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Title:	Linear and nonlinear optical properties of polymer-ZnO-CuO nanocomposites
Authors:	Haider Mohammed Shanshool (P59650)
Keywords:	Polymer/ZnO nanocomposites Optical properties Linear Nonlinear Optical limiting devices Dissertations, Academic -- Malaysia
Issue Date:	Jan-2016
Description:	Polymer/ZnO nanocomposites have received a great interest in linear and nonlinear optical properties because of their potential application such as optical switching and optical limiting devices. This thesis reported the study concerning the linear and nonlinear optical properties of ZnO nanoparticles which embedded in the polymer matrix. A flexible foil-like polymer/ZnO nanocomposite was prepared via casting method. In the typical procedure, various concentrations of ZnO nanoparticle (0, 1, 3, 5, 10, and 15wt %) that acted as a filler were incorporated into different types of polymer matrix which were polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polystyrene (PS) and polyvinyl alcohol (PVA) by mixing approach. Moreover, linear and nonlinear optical modification on as-prepared polymer/ZnO nanocomposites, as a foil, composed of 10wt% was also studied through the addition of (1wt %) CuO nanoparticles. Then, PMMA/ZnO and PVDF/ZnO nanocomposites were chosen to prepare as a thin film on quartz by spin coating and casting respectively. It was found the as-prepared samples shown an intense linear absorption spectra at the range wavelength of 370-377nm indicating the existence of ZnO nanoparticles arise from the exciton transition. The linear transmittance spectra was found inversely proportional to the ZnO nanoparticles concentration while reverse phenomenon was observed in reflectance spectra in the UV region. In addition, it was noticed that the optical band gap of the samples were red shifted, that was proved from photoluminescence (PL) analysis. Furthermore, the purity and composition of the nanocomposites were confirmed via FTIR, EDX analysis and EDS mapping. Surface morphology of samples was tested by FESEM that were shown the dispersion of ZnO nanoparticles successfully. The optical absorptive and refractive nonlinearities parameters such as absorption coefficient and refractive index of the as-prepared sample were analysed using an open and closed aperture single beam Z-scan technique via Q-switched Nd-YAG pulse laser at 532nm. The nonlinear refractive index was in the order of 10-12 cm2/W with a negative sign whereas the nonlinear absorption coefficient was in the order of 10-7cm/W for samples prepared as foil. The real part, imaginary part and the absolute value of the third order nonlinear optical susceptibility χ (3) were calculated. The χ(3) was in the order of 10-6 esu for foil samples which indicated the effect of the percentage of ZnO nanoparticles and the types of polymer matrix on those parameters. The effect of adding CuO nanoparticles to nanocomposites as foil was observed, and enhanced their linear absorption and nonlinear optical properties. Consequently, a good optical limiting was obtained. In order to evaluate the suitability of the samples as optical limiting, the optical limiting threshold of the samples was measured by transmittance technique. The results showed that the prepared nanocomposites can be considered as an excellent candidate for optical limiting devices, which clearly affected by the concentration of ZnO nanoparticles and polymer matrix. Nanocomposites PMMA/ZnO/CuO and PS/ZnO/CuO showed the low optical limiting threshold, which were equal to 60Mw/cm2 and 50Mw/cm2 respectively.,Certification of Master's/Doctoral Thesis" is not available
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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