Effect of MWCNTs and P[MMA-IL] on the crystallization and dielectric behavior of PVDF composites

Abstract

Multiwall carbon nanotubes (MWCNTs) and MWCNTs modified by copolymer (P[MMA-IL]) with 1-vinyl-3-ethyl imidazole bromine ionic liquids (IL) and methyl methacrylate (MMA) were incorporated into polyvinylidene fluoride (PVDF) by solution mixing. MWCNTs modified by P[MMA-IL] exhibit better dispersion than that these modified by PMMA. Modified MWCNTs can promote the Tc and Tm of PVDF because of the appearance of β crystalline phase. XRD and FTIR-ATR results confirm that PMMA and MWCNTs cannot induce the β phase, but P[MMA-IL] and MWCNTs can promote the content of β phase due to the ion-dipolar interaction between the imidazolium cation of IL and the >CF2 of PVDF, and the strong induction is brought by the template of MWCNTs. The experimental dielectric data were analyzed within the formalism of complex permittivity and electric modulus. In the frequency spectra of PVDF/P[MMA-IL]/MWCNTs composite, MWS interfacial polarization and electrode polarization result in high value of dielectric permittivity that is related to the large number of the mobile charge carriers. The conductivity relaxation of PVDF/P[MMA-IL]/MWCNTs composite is thermally activated with the hops of charge carriers because P[MMA-IL]/MWCNTs can improve the hops of charge carriers through amorphous and interphase region by ion-dipolar interaction and dipolar ordering reinforced by the template of MWCNTs.