Study On Preparation,Dielectric And Thermal Conductive Properties Of Poly(Vinylidene Fluoride)/Silicone Carbide Nanowire Composites

In this paper,silicon carbide(SiC)nanowires with both thermal conductivity and semiconductor properties are used as the main fillers to explore the basic theory and technology of preparing PVDF based dielectric composites with high dielectric constant,low dielectric loss and high thermal conductivity from the perspective of polymer processing.The internal relations among the microstructure,dielectric properties and thermal conductivity of the composite were clarified.The specific research results are as follows:(1)PVDF/SiC nanowire composites were prepared by solution mixing method,and the influence of its microstructure on the dielectric and thermal conductivity was studied.The results show that the incorporation of SiC nanowires can effectively improve the dielectric constant of the composite.The dielectric loss of the composite is closely related to the dispersion of SiC nanowires.When the content is 13.8 vol%,the unmodified SiC nanowires interweave with each other in PVDF matrix to form a leakage path,which greatly improves the dielectric constant and significantly increases the dielectric loss.The surface aminated SiC nanowires can be arranged in parallel in PVDF matrix,which improves the dielectric constant while maintaining a low dielectric loss.The dielectric constant is as high as 23.3 at1 KHz,but the dielectric loss is only 0.048,which is 1/4 of the same content of unmodified SiC nanowire filled PVDF matrix composite.In addition,the thermal conductivity of the composite is also improved by SiC nanowires.(2)In order to further improve the thermal conductivity of PVDF/SiC nanowire composites,the parallel SiC nanowires in PVDF matrix are “bridged” by hexagonal boron nitride(h BN)to form a thermal conduction path.The thermal conductivity of the prepared PVDF/h BN/SiC nanowire composite is significantly improved,while maintaining high dielectric constant and low dielectric loss.Among them,the thermal conductivity of PVDF/h BN/SiC nanowire(100/20/26,w/w/w)ternary composite is as high as 1.41W/(m·K),which is about 5.9 times as that of pure PVDF.At the same time,its dielectric constant and dielectric loss at 1 KHz are 18.5 and 0.05 respectively.(3)PVDF/PAN/SiC nanowire composite was prepared by solution mixing of PVDF and polyacrylonitrile(PAN)as matrix materials,and its morphology,dielectric and thermal conductivity were characterized and analyzed.The results show that the PAN content in the blend composites has a significant effect on the dielectric properties.When PVDF/PAN/ SiC nanowires {(90/10)/15,w/w/w} blend composite is at 1 KHz,the dielectric constant is as high as 48,the dielectric loss is 0.14 and the thermal conductivity is 0.39 W/(m·K).