Investigation on dielectric properties of sandwich-structured fluoroelastomer/PVDF films containing graphene

The sandwich-structured FKM/PVDF film with different GNP components fabricated via the hot-pressing technique were studied by dielectric relaxation spectroscopy over a range of frequency (20 Hz-30 MHz) and temperature (25-205 degrees C). Compared with single-layered PVDF film, the curie transition temperature (Tc) and melting temperature (Tm) of sandwich-structured FKM/PVDF films obviously increase, but their crystallinities decrease. The permittivities of sandwich-structured FKM/PVDF films are higher than single-layered PVDF film throughout whole temperature range, and the dielectric losses of three films have a little change. In addition, the Cole-Cole plots and electric modulus spectra of all films reveal the non-Debye relaxation behavior. odc of sandwich-structured FKM/PVDF films increase slightly compared to single-layered PVDF film, and oac decreases. Both E tau and Eo of sandwich-structured FKM/PVDF films slightly decrease due to the combined effect between the high conductivity of GNP and the barrier effect of layer/layer interface. A higher Ue of 8.1 J/cm3 can be obtained at 350 MV/m for sandwich-structured film with 0.5% GNP. The sandwich-structured FKM/PVDF films with low content GNP have potential application in dielectric material.