Effects of initial crystallization process on piezoelectricity of PVDF-HFP films

Abstract

The effects of some important factors in the initial crystallization process of the solution casting method on the piezoelectricity of poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP) films were extensively explored. The experimental results revealed that there is an optimal initial crystallization temperature at around 90°C. The slow cooling speed can moderately enhance the degree of crystallinity. The most important finding was that a bilayer crystalline structure caused by an asymmetrical heating pattern can enhance the formation of packed micro-fibrillar morphologies after drawing. These three points can increase the piezoelectricity of the PVDF-HFP films, indicating the increase of the extended-chain crystals ( β-phase).

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

“…Results also indicate that the narrow short cantilever-type PEG generates the highest power densities between 4 m s -1 and 7.5 m s -1 , whereas at 8 m s -1 the short cantilever generates the highest volumetric power density at approximately 1.5 mW cm -3 . 123 The study further reports that a maximum generated volumetric power density of 2.0 mW cm -3 is obtained for the narrow short cantilever with a load resistance of 30 MΩ. However, no data is shown for the influence of the variation of load resistance on the electrical output of the wind-powered PEGs.…”

“…3e). 114,[122][123][124] The HFP group is significantly larger than the TrFE group, hence lower HFP molar ratios are required for the manufacture of semi-crystalline copolymers, induced by steric hindrance.…”