Preparation Of Isolation Filled ABS Composites And Research On Their Electrical And Thermal Conductivity

With the rapid development in the field of electronics and communication,the application demands of electrical and thermal conductive composites increase,and higher requirements are also put forward for the properties of materials.It is necessary to add a large number of fillers to the polymer matrix to improve the polymer by electrical and thermal conductive properties,which will affect the performance of the plastic itself at the same time.The most direct way to reduce the adverse effects on plastic properties is to add fewer fillers to achieve the same properties.The structure design of plastic matrix and the segregated structure to reduce the content of fillers are the most efficient methods.Most of the segregated structures are structured on incompatible plastic,or fillers are mainly distributed on the interface of plastic matrix.Not only the mechanical strength of the composites will be affected,but there is room for further reduction in the amount of filler.This paper further explore the segregated structure and reduce the amount of filler to improve the performance of electrical and thermal conductive.Acrylonitrile-butadiene-styrene copolymer(ABS)and polycarbonate/acrylonitrile- butadiene-styrene copolymer alloy(PC/ABS)were used as polymer matrix to fill multi-walled carbon nanotubes(MWCNTs).Conductive composites with uniform and segregated structures were prepared by methods of melt mixing,solution mixing and solution-mechanical mixing.The conductive threshold of ABS/MWCNTs composites with uniform structure prepared by solution mixing method was 0.5 wt%.ABS/0.5wt%MWCNTs was used as conductive fillers to prepared PC/ABS/MWCNTs segregated structures composites in solution-mechanical mixture method with conductive threshold of 0.05 wt%.The tensile strength of the conductive composites was 40 MPa,close to pure ABS.The shielding performance of the segregated structures conductive composites filled with 7 wt%MWCNTs was 50-80 d B and the same as uniform structures conductive composites filled with 10 wt%MWCNTs in the electromagnetic wave with a frequency of 30 MHz-1000 MHz.Graphite and Boron nitride(BN)were added into ABS matrix by melting mixing,mechanical mixing-hot pressing to prepare thermal conductive plastics with uniform and structure.The segregated structure can significantly improve the thermal conductivity.And composites with graphite has a higher thermal than BN at the same filler content.The thermal conductivity of segregated structure composites with 10 wt%graphite was 0.69 W/(m·K).Although ABS/graphite segregated thermal conductive composites has high thermal conductivity,it also affects the electrical insulation performance.ABS/graphite/BN with layered-segregated structure has excellent thermal conductivity and electrical insulation performance.With 10 wt%graphite/BN(mass ratio 50/50)filling,the thermal conductivity of the layered-segregated was 0.65 W/(m·K),and volume resistivity was 10¹⁴?·cm.