Preparation Of Polyimide Composite Film With High Dielectric Constant

With the development of science and electrical,the demand of composite with high dielectric constant is increasing,as well as its performance requirements.Using the composite method to put the toughness of polyimide and the high dielectric constant of ceramic into together,has been aroused more and more attention.In this paper,the polyimide was prepared using 3,3',4,4'-biphenyl dianhydride(BPDA)and 4,4'-diaminodiphenyl ether(ODA)as raw materials,N,N'-dimethylacetamide(DMAC)as solvent,calcium copper titanate(CCTO).A series of CCTO/PI composites which had different mass fraction of CCTO were obtained by solvent-in situ polymerization and press-evaporation polymerization.The composites were characterized by Fourier transform infrared analysis(FT-IR),Scanning electron microscopy(SEM),LCR bridge,Differential scanning calorimetry(DSC)and Thermogravimetic analysis(TGA),respectively.The results reveal that the CCTO/PI composites were dispersed homogeneously in the polyimide matrix using in situ polymerization.With the incorporation of CCTO which mass fraction is 90%,the dielectric constant of the composites reached 101.5 at 100Hz and the disruptive strength reached 10.3kv/mm.With the incorporation of CCTO which mass fraction is 90%,the dielectric constant of the composites reached 112.3 at 100Hz,which was 33 times larger than that of the PI,and the disruptive strength reached 43.5kv/mm using press-evaporation polymerization.The thermostability of CCTO/PI composites was excellent and its thermal decomposition temperature of 5%was above 579?.