Preparation and characterization of flexible PVDF-HFP film for piezoelectric applications

Abstract

We report on the preparation of electroactive β-phase in polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) without any electrical poling treatment. The PVDF-HFP film with various mass fractions (wt%) of magnesium chloride hexahydrate salt (MgCh∼6H2O) was fabricated by a solution casting technique. The morphological, mechanical, structural and dielectric properties were investigated. Results founded that the PVDF-HFP composite films show a large number of micro-pores on the top surface as a sponge-like structure. The Young's modulus and crystallinity values tend to be linearly decreased with the MgCh2>6H2O concentration leading to enhance flexibility. The largest β-phase fraction of 87.2% is found in the composite with 1 wt% MgCh2>6H2O filler. The obtained value is 4 times higher than the value of unfilled PVDF-HFP. Moreover, the maximum value of dielectric constant is about 19.2 at 10 Hz for 4 wt% MgCh2>6H2O filler. Therefore, the modified composites with the excellent flexibility, dielectric constant and β-phase may be a promising material for applications in the field of piezoelectric energy conversion.