| Barium titanate filler is a kind of high dielectric material.The high dielectric composite material composed of barium titanate filler and polymer matrix has been widely used in the fields of high energy storage capacitors,cable joints and terminals,microwave absorbing stealthy materials,high capacity organic film capacitors and bioengineering.However,due to the poor combination ability of inorganic filler and matrix and poor mechanical properties of composite material,how to improve the filler The dispersion of fillers in the matrix and the improvement of the interaction between fillers and the matrix have always been the research focus.The results show that barium titanate,a high dielectric ceramic material,can improve the dielectric properties.By improving the morphology of barium titanate filler,the dispersion of barium titanate in the composite can be improved,so as to further improve the dielectric properties.Through the surface modification of barium titanate,the core-shell structure filler can be prepared,which can effectively reduce the agglomeration of filler in the matrix,prepare a more uniform multi-phase high dielectric composite,improve the dielectric properties,strengthen the bonding ability with the matrix,and improve the mechanical properties of the composite.In addition,the dielectric properties of the matrix material can be further improved and the mechanical properties of the matrix material can be improved.Therefore,in order to improve the dispersion of fillers in the matrix and explore the factors that affect the dielectric properties of the composite,the following work has been completed to obtain high-performance dielectric polymer composite:(1)Three series of high dielectric composite were prepared by using BaTiO3 nano-rod,BaTiO3 nano-particle,and BaTiO3 micro-particle as fillers respectively,and polyvinylidene fluoride(PVDF)as matrix.The dielectric properties of the composite were tested by impedance analyzer,and the effect of BaTiO3 shape on the dielectric properties of composite was studied.The results show that with the increasing of the BaTiO3 filler,the dielectric constant of the composites increases obviously,and the dielectric loss is low.When the frequency of electric field is 1 kHz,the dielectric constant of 40vol%BaTiO3 nano-rod/PVDF composite is the highest,which reaches 24.1.(2)ILS@BT core-shell nanoparticles were prepared by click chemistry method.The dielectric properties of ILs@BT/PVDF composite were studied.Through the hydroxyl condensation reaction,trimethoxysilane(KH590)was grafted on the surface of nanoparticles,and then 1-butyl-3-vinyl imidazole(VBIMBR)was grafted on the surface of fillers by sulfhydryl allyl click chemical method.Finally,the core-shell fillers were obtained.The synthesis process of the filler was characterized by IR and SEM,and the dielectric properties of the composite were studied.Through the surface modification of barium titanate and grafting of ionic liquid,the interfacial compatibility and force between the filler and the matrix were improved.The effects of different grafting amount of fillers and the same grafting amount of fillers on the dielectric properties of the composite were also discussed.(3)ILs/PDMS composite with high dielectric and mechanical properties was prepared by double crosslinking.Firstly,the(3-Mercaptopropyl)trimethoxysilane(KH590)and 1-butyl-3-vinyl imidazole(VBIMBR)were grafted together by click chemistry method to obtain the coupling agent modified by ionic liquid.Then a kind of composite material with high dielectric and mechanical properties was prepared by using the modified coupling agent and tetrabutyl silicate(TEOS)cross-linked hydroxyl terminated silicone oil to directly combine the filler with the matrix.By changing the ratio of coupling agent and silicone oil,the influence of modified fillers on dielectric properties and mechanical properties was explored. |
