Effect of cesium bromide on the structural, optical, thermal and electrical properties of polyvinyl alcohol and polyethylene oxide

Abstract

The molecular structures of polyvinyl alcohol and polyethylene oxide doped with various concentrations of CsBr were investigated by FT-IR, UV/Vis. and XRD. The surface of the prepared films was studied by SEM. Thermal and electrical properties were studied via TGA, DSC and DC electrical conductivity to use as a sensor in electronic devices. X-ray diffraction displays the semicrystalline nature of PVA/PEO, characterized by two broad bands at 2θ ≈19 and 23°, which decreased by increasing cesium bromide. FT-IR spectra revealed that there is a change in intensities of some bands compared with the spectrum of the pure blend. This indicates that interaction and complexation between PVA/PEO polymer blend and the filler took place in amorphous regions. UV/Vis. spectroscopy revealed that the values of the optical energy gap are decreased with increasing the CsBr concentration, which decreased from 5.90 to 4.90eV for direct transition and decreased from 4.72 to 3.51eV for indirect transition. TGA curves depicted that the thermal stability of samples was changed. DSC analysis showed a single glass transition temperature (Tg=60°C), which confirms the miscibility of the prepared films. The DC graph showed that the conductivity of the samples had been increased with increasing the fillers content and the activation energy was decreased from 1.03 to 0.36eV. SEM displays transparent, soft and a uniform surface for polyvinyl alcohol and polyethylene oxide while after adding CsBr there is a semi- tori/ granules randomly distributed on the surface.