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In this work, in order to reduce the energy loss induced by the ferroelectric P(VDF HFP) and improve energy storage property, a series of P(VDF HFP)/PMMA blend films were prepared via biaxially oriented technology. The results showed that the ratio of alpha crystal continuously decreased with the addi tion of PMMA, the ratio of beta crystal firstly increased, followed by a reduction with further rising the PMMA percentage. Though gamma ratio was small, it enhances steadily. With the addition of PMMA, it could be found out the disorder in crystal structure, the reduction in crystal size, and the drop in crystallinity of P(VDF HFP). The structure change improved the discharge efficiency and temperature stability. With the addition of PMMA, tanδ is enhanced more than 10°C, and the discharge energy efficiency improved from 45% of pure PVDF to 75% under 400 MV/m after modifying with PMMA. This improvement in the dis charge energy efficiency is thought due to the formation of new crystal γ 2b.

Dielectric and conductivity relaxation behaviors of Poly (vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] and its composites are investigated on the basis of dielectric relaxation spectroscopy at 20 to 200°C and 20–5 M Hz. We have observed that imaginary modulus spectra exhibit asymmetry peak with peak-width much broader than that of the debye peak. The peaks are skewed toward the high frequency sides due to conductivity. Treating the imaginary parts of complex modulus spectra with Kohlrausch-Williams-Watts (KWW) and Havriliak-Negami (HN) equations, it is found that the obtained low shape parameters (α, γ) and non-exponential parameter (β) gradually decreases with PC composition increasing, indicating that a wide distribution of relaxation times which belong to non-Debye-type relaxation process. The both activation energies (Eτ and Eσ), which are attributed to contributions of multiple relaxation processes, are very close at corresponding sample. But, Eτ and Eσ gradually increase with PC composition increasing.