Preparation And Properties Of Thermal Conductive Acrylonitrile-Butadiene-Styrene/boron Nitride Composites

With the development of national economy and progress of science and technology,the requirements for high thermal conductivity of packaging and housing materials are put forward,as massive high frequency micro-electronics and high power electrical equipment are utilized nowadays.Researches focus on polymer matrix thermal conductive composites,because of their light weight,low price,good processability,excellent insulating and mechanical properties.Acrylonitrile-butadiene-styrene(ABS)copolymer possesses superior strength,toughness and process performance.Thus,it is widely applied in the fabrication of household appliances,automotive parts and LED products.Hexagonal boron nitride(h-BN),with high thermal conductivity and chemical stability,reliable electrical insulation,ultra-low dielectric constant and thermal expansion coefficient,is the most promising filler to prepare insulating thermal conductive composites.In this paper,ABS thermal conductive composites were fabricated by melt blending using h-BN as thermal conductive filler.The influences of preparation method and surface modification on the composites properties were investigated.Melt blending is one of the most commonly used methods to fabricate polymer composites,which can ensure uniform dispersion of the fillers in the matrix under strong shear force from the two-screw extrusion.In addition,this method is easily operated and can achieve continuous production.The ABS/BN composites were prepared by extrusion mixing and injection molding.The results of SEM observation showed that BN platelets with in-plane orientation were homogenously dispersed in the ABS resin.The thermal conductivity of the prepared composites exhibits continuous increase with the addition of BN loading.As BN content is 20wt%,the thermal conductivity of the ABS/BN composites reached to 0.404 W/(m·K),2.30 times of the neat ABS.Meanwhile,the tensile strength and fracture toughness are both significantly improved.The interfacial interaction of inorganic fillers and polymers is an important factor affecting the global properties of composites.Based on catechols self-polymerization and adhesion to the surface of solid materials under oxidizing conditions,poly(DOPA)was synthesized by in-situ polymerization on the surface of BN particles with L-DOPA as the monomers,coated BN(DBN)noncovalently.Results showed that the interfacial compatibility between BN and ABS matrix was enhanced by the poly(DOPA)layer,which was beneficial to improve the thermal conductivity and mechanical properties of the composites.With 20wt% filler loading of DBN,the thermal conductivity of the composites was up to 0.501 W/(m·K),2.63 times of the neat ABS.The impact toughness of the ABS/DBN composites is superior to that of the ABS/BN composites,especially at 1wt% and 2wt% filler contents.Simultaneously,excellent electrical insulation of the composites was maintained at a high level,and the storage modulus,Tg,thermal stability were improved to have a practical use of this material in electronic and electrical fields.