Piezoelectric properties of hot compression molded PVDF/SiC nanocomposites

Poly(vinylidene fluoride), PVDF, has been studied extensively because of its outstanding piezoelectric properties. PVDF shows five crystalline polymorphs known as α, β, γ, δ, and ε phases. Among them, the β phase exhibits piezoelectric properties, but the α phase is thermodynamically more stable. The incorporation of additives into PVDF can promote β phase formation. In this study, PVDF-nano SiC composites with different SiC contents were fabricated through hot compression molding and the effects of SiC on the crystal structure, crystallinity and piezoelectric properties of PVDF were studied. The microstructure of the composite samples was investigated by SEM. The prepared samples were perfectly dense with a density more than 97% of the theoretical density. The amount of β phase was determined by FTIR analysis and the crystallinity of the PVDF was deduced from DSC analysis. Finally the piezoelectric properties of the samples were measured by a piezotester. The results showed that by increasing SiC content up to 1 wt%, the amount of β phase, crystallinity and sensitivity of the samples increased and then decreased afterwards.