Syudy On Preparation And Properity Of Percolative Polyvinylidene Fluoride Composite Film

When conductive fillers are added into the polymer, according to the percolatingeffect, the composite material can achieve a high dielectric permittivity, with fillers’volume fraction close to the percolation threshold. This kind of composite materials cannot only under less filler content obtain the high dielectric permittivity, but also get thegood processability brought by the polymer. These excellent comprehensive propertiesmake them attract more and more attentions in electrical and electronic fields.In this paper, PVDF was chosen as the polymer matrix, while the PANI andMWCNTs were chosen as the filler. The PVDF/PANI, PVDF/MWCNTs andPVDF/MWCNTs/PANI composite films were prepared by solution cast method. Inaddition, we also prepared PVDF/MWCNTs@PANI composite films, whileMWCNTs@PANI was made by in-situ polymerization. Their dielectric properties,crystallization behaviors and microstructures were characterized, followed by the study ofinfluence of conductive fillers, preparation technology on the performance of thecomposite films.The dielectric permittivity of PVDF/PANI films increases as the content of PANIincreased. The film achieved the percolation threshold, when the content is10.5wt%, atwhich the dielectric permittivity is75. Compared with the PVDF/PANI films, thePVDF/MWCNTs composite films have a lower percolation threshold, which is only1.5wt%. The three-phase PVDF/MWCNTs/PANI composite films have better dielectricproperties than two-phase films.All these films were analyzed by XRD, FTIR and DSC. We find that both PANI andMWCNTs have an effect on the crystallization of PVDF, transferred from α phase to γphase.The MWCNTs@PANI prepared by in-situ polymerization has an average diameter(20μm). Observing the SEM figure, the PANI particles did not get together. ThePVDF/MWCNTs@PANI films have a higher dielectric permittivity than thePVDF/MWCNTs/PANI composite films, while the dielectric loss is much lower.