Research On Impact Of BaTiO₃ On Dielectric Properties Of Different Phase PVDF Based Nanocomposites

As the new energy technology and power electronic technology advance,equipment used for energy storage and conversion need to have higher energy storage density and higher power density,which means materials require increasing energy storage characteristics.Therefore,the polymer matrix composites with superior processing performance and high breakdown field have attracted many researchers’attention.We use to separate nanocomposite into three individual part,matrix,filler and boundary.However,there usually is affection filler works on polymer matrix.So in order to understand interaction between them,crystalline behavior as phenomenon is studied.PVDF has attracted a lot of attention due to its relatively high dielectric constant and breakdown field strength,however,PVDF as polymorphy has five different crystalline forms,and each one has different characteristic.In this article,using untreated and hydroxylated BaTiO3 nanoparticle and PVDF through different processing methods,nanocomposites with three different common kinds of PVDF polymorph are obtained.Measuring and analysis of dielectric properities and crystalline behavior are perforemed.Study the relation between macro dielectric propeirties and interaction between BaTiO3 nanoparticles and different PVDF polymorphs and function of boundary.Aim to deeper understand mechanisms in nanocomposites,and improve the energy storage density of dielectric material more targeted,and mainly includes the following contents:(1)Using XRD,FTIR and DSC etc.methods,the crystallization behavior of matrix in nanocomposite is characterized.Analysis of matrix’s grain size,crystal phase and crystallinity shows in article.The results suggest that the effect of BaTiO3 nanoparticles on the crystallization behavior of matrix has two sides.It both act as a heterogeneous nucleating agent,increase the nucleation and growth of crystal,and then inhibit the further growth of grain.In addition,it is inferred that BaTiO3 nanoparticles favor the formation of beta phase crystal,and does not favor the gamma phase crystal..(2)Basing on dielectric spectrum analysis of nanocomposite with different crystal phase,BaTiO3 nanoparticles help enhance interfacial polarization.According to the analysis of the crystallization of matrix,the different changes of polarization relaxation time as the filling rising are analyzed.It suggests that crystalline region-amorphous boundary plays a main role in changing relaxation time.(3)Through surface hydroxyl ate BaTiO3 nanoparticles,analyzes the hydroxyl’s effect on the crystallization behavior of matrix.The hydroxyl weaken the influence of BaTiO3 nanoparticles on the crystallization behavior of matrix.Moreover,measure the dielectric spectrum,which shows hydroxyl increases carrier mobility,shorten the relaxation time,enhances and phase nanocomposites’ interfacial polarization,and suppresses the phase nanocomposite’s interfacial polarization.