Preparation And Properties Of P(VDF-HFP)/EP/CNT Three-phase Composite

With the rapid development of integrated circuits,the demand for dielectric energy storage materials in microelectronic components is greatly increased,so it is necessary to have high dielectric constant and good mechanical properties.However,the current research is limited to electrical properties,and this article comprehensively studies the mechanical properties based on actual conditions.In this paper,polyvinylidene fluoride hexafluoropropylene copolymer P（VDF-HFP）with high dielectric constant is selected as the polymer matrix.By adding epoxy resin（EP）and carbon nanotube（CNT）,and the CNT was purified by pickling,surface grafting and epoxidation.,a series of P（VDF-HFP）/EP/CNT composites were prepared by solution treatment,and their electrical and mechanical properties were studied.The main contents and results of the study were as follows:P（VDF-HFP）and F-51 phenolic epoxy resin were used to prepare P（VDF-HFP）/EP two-phase composites.The influence of F-51 addition amount on the properties of composite films was investigated by changing the content of F-51.It was found that F-51was evenly distributed in the matrix,entangled with P（VDF-HFP）,existed in the form of enriched small particles,played a heterogeneous nucleation role,and induced P（VDF-HFP）to produce a polarβphase.When F-51 content was 1%,the dielectric constant of the composite film was up to 21,the breakdown strength decreased slightly,and the tensile strength increased by 34.57%.CNT were purified and oxidized with concentrated sulfuric acid and concentrated nitric acid to generate carboxyl groups on the CNT surface.TPP was used as a catalyst to prepare CNT-EP,which containing epoxy resin on the surface.F-51 was successfully determined by FTIR,TG,and TEM analysis.P（VDF-HFP）/EP/CNT-EP composites were prepared by solution method.DSC,FTIR and XRD analysis showed that the addition of CNT-EP increased the polarityβphase content.The dielectric constant increased to 19,but in the low frequency band the dielectric loss was reduced to 0.06.The breakdown strength decreased to 141.66 MV/m;The mechanical properties of composite films were reduced to different degrees.This was due to the F-51 grafted on the CNT surface,which formed a protective layer of insulation on the CNT surface,reducing direct contact between CNT.The m-CPBA was used as the over-oxidant to epoxide the acidified CNT directly.FTIR analysis found that the epoxy group appeared at 916 cm^-1.DSC analysis showed that with the addition of m-CNT,the crystallinity ofαphase increases and the crystallinity ofβphase decreased.In the XRD analysis,the formation of the weakly polarγphase was shown.After the CNT amount reached 2%,the percolation threshold was reached,the dielectric constant of the composite film containing 3%m-CNT was as high as 36;The minimum breakdown strength was still 103.96 MV/m;The elongation at break and tensile strength of the composite film both decreased by 2%,and the decreases were 40%and 34%respectively.The yield strength and the young’s modulus were opposite,and after 2%,the yield strength was greatly improved,among which,the yield strength was up to 15.6 MPa at 3%,which was 50%higher than that without addition.