Crystalline Phases Thermal Behaviour, Optical Energy Band Gap, and Broadband Radio Wave Frequency Dielectric Properties of PEO/PVDF Blend Films

摘要

Different composition ratios poly(ethylene oxide) (PEO) and poly(vinylidene fluoride) (PVDF) blend films (PEO/PVDF) were investigated by employing a differential scanning calorimeter (DSC), ultraviolet-visible (UV-Vis) spectrophotometer, and radio frequency impedance analyzer (RF-IA). Crystalline phases of the PEO and PVDF in the blends, their melting temperatures and the degree of crystallinity were determined using the DSC thermograms. These structural parameters of the semicrystalline polymers explain a significant alteration in heterogeneous chains interaction with the composition variation of the constituents in the PEO/PVDF blends. The UV-Vis range absorbance spectra of these blend films were reported and analyzed for the determination of their optical energy band gap values. The decreased band gap values of the polymer blends as compared to that of the pristine polymers evidenced a considerable structural disordering of the polymers functional groups which cause the creation of the localized states that assisted the electronic transitions. The RF range dielectric permittivity of the PEO/PVDF blend films showed a gradual decrease with sweeping the frequencies from 1 MHz to 1 GHz, but it enhanced anomalously at the starting frequencies when the PVDF amount was relatively increased in the polymer blend. The alternating current (AC) electrical conductivity of these blends exhibited a linear variation with the change of frequency, and it notably altered at a fixed frequency when the polymer composition ratio in the blend films was varied. These experimental results of the PEO/PVDF blend films are highly creditable to emerging polymer-based flexible technologies of radio-electronic and optoelectronic devices.