Dependence of Mechanical and Dielectric Properties on Temperature of Poly(Vinylidene Fluoride-Hexafluoropropylene)

Abstract

Recently, pyroelectric polymers i.e. polyvinyledene fluoride (PVDF) and its copolymer of P(VDF-TrFE), including poly (vinylidene fluoride-hexafluoropropylene) - P(VDF-HFP) have been reconsidered greatly for energy conversion or energy harvesting. This work study the effect of temperature on mechanical and dielectric properties of thin film P(VDF-HFP). All samples were prepared by solution casting method then stretched and poled at 35 μm/s of velocity and 60 MV/m of electric field, respectively. The dielectric properties were determined by LCR meter varying on temperature (30°C to 155 °C) at 1 kHz. For mechanical properties were investigated by dynamic mechanical analysis (DMA) which explained the viscoelastic behavior and obtained a glass transition temperatures (Tg) of all samples. The range of operated temperatures is-100 °C to 100 °C in rate 5°C/min. The results showed a tiny shift of Tg among non-stretched, stretched, and polarized P(VDF-HFP) which is related to their degree of crystallinity and ability of polarization on dielectric behavior of sample. Correlation of the temperature dependence of mechanical and dielectric properties under stretching and poling of these polymers are also discussed.