Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physics

The present thesis deals with the preparation of blends of Poly (ethylene oxide) (PEO) and poly (vinylidene fluoride) (PVDF) films of compositions (50/50, 40/60, 30/70 and 20/80 wt/wt %) by casting technique. XRD, DSC and FT-IR were studied for all samples. (20/80 wt/wt %) PEO/PVDF blend provides the proper blending of these polymers. (20/80 wt/wt %) PEO/PVDF blend doped with concentrations 0.5, 0.7, 1.0, 2.0, 5.0 and 7.0 wt% Li₄Ti₅O₁₂NPs were prepared using casting technique. Structural, optical and thermal properties of polymer nanocomposites are investigated by using XRD, HRSEM, EDS, FT-IR, UV-Vis, DSC and TGA. Also, dielectric properties were studied. XRD, FT-IR and DSC data show that there is an interaction between the blend sample and Li₄Ti₅O₁₂ NPs. Also, the addition of Li₄Ti₅O₁₂ NPs decreases the degree of crystallinity of the blend sample. From TG data and the calculated activation energies revealed that the thermal stability of (20/80 wt/wt %) PEO/PVDF improves by addition of Li₄Ti₅O₁₂ NPs. HRSEM images reveal that the presence of Li4Ti₅O12 NPs leads to changes in the surface morphology of the nanocomposites and gives rise to crystalline domains up to 5wt% Li₄Ti₅O₁₂ NPs, then deteriorations is occurred. The addition of Li₄Ti₅O₁₂ NPs to the (PEO/PVDF) enhances the electrical conductivity of the blend attributed to charge carrier build up and increases in segmental mobility of polymeric chains

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