Preparation And Dielectric Properties Of Poly(Aryl Ether Ketone) Matrix Nanocomposites

With the rapid development of modern electronics and electrical power systems,there is a growing need for electrical energy storage devices.The continuous miniaturization and increased functionality in modern electronics and electric power systems demand further increases in energy and power density of dielectric materials.Compared with ceramic,polymer-based materials possess a set of desired properties,such as low cost,high power density,high dielectric strength,low dielectric loss and flexibility.However,they also have their own shortcomings in the fields of application.The glass transition temperature of most polymers is relatively low.Above the glass transition temperature,the free volume in the polymer increases significantly and the polymer molecular chain moves more easily,which leads to higher dielectric loss and damages the dielectric stability.If the polymer-based materials are able to operate stably at high temperature,there may be a much more broader application field.In this paper,the crosslinkable Poly?aryl ether ketone??DPAEK?was selected as the matrix,and surface modified barium titanate nanoparticles?BT?and boron nitride nanosheets?BN?were used as the fillers.The films were formed by solution casting method,and the cross-linked polymer-based nanocomposites with nanoparticles as the"crosslinking point"were constructed by heat treatment.The fillers and the matrix were tightly bonded by chemical bonds,thus the reinforced interfaces can effectively inhibit the relaxation of polymer molecular chain at high temperature.In the first part,barium titanate nanoparticles with high dielectric constant were selected as the filler,and reactive functional groups were modified onto the surface of the nanoparticles.Meanwhile,cross-linkable poly?aryl ether ketone?containing side propenyl groups was designed and synthesized.Through heat treatment,the crosslinking reaction may occur at the interface between the fillers and the polymer matrix.It is found that BT-BCB/c-DPAEK possess excellent mechanical properties,dielectric properties and energy storage properties,and may maintain relatively stable at high temperature.The discharge energy density of BT-BCB/c-DPAEK is 1.75 J cm^-3at 300 MV m^-1 at 150 ^oC,and the efficiency is about 80%.In the second part,a two-dimensional material,BN nanosheets,were selected as the filler,and the cross-linked network structure was constructed by the same method as the first part.BN may be considered as a promising material for dielectric nanocomposites,for it possess ultra high dielectric strength due to its wide band gap energy.BN also has high plane thermal conductivity,which may be helpful to avoid thermal breakdown caused by heat accumulation in materials.The discharge energy density of BN-BCB/c-DPAEK is 3.83 cm^-3 at 500 MV m^-1 and 150 ^oC,while the efficiency is 90.6%.