Preparation And Properties Of Thermally Conductive Polycarbonate/Boron Nitride Composites

With the rapid development of electronic information technology,more and more heat was generated.The heat dispersion has already become a noticeable issue.Owing to the poor corrosion resistance or bad processability,traditional conductive materials are being replaced by polymer-based materials.Polymer-matrix thermal conductive material,with excellent insulation,thermal conductivity,low cost and easy processing,was an ideal material for heat dispersion.Filling with high thermal conductivity fillers is a familiar way to prepare polymer-based thermally conductive composites.Hexagonal boron nitride?h-BN?,with excellent thermal conductivity,superior electrical insulation and high thermal stability,was the ideal filler for preparing thermally conductive and electrically insulating composite.In this paper,thermal conductive and electrically insulating polycarbonate?PC?composites were prepared by filling with BN.The thermal conductivity and thermal stability of composite were greatly improved.The effects of surface modification and filler contents on the properties of PC composites were investigated.The properties of composites are significantly affected by the distribution behavior of the inorganic filler.Basing on the“sonication-assisted hydrolysis effect”,we decreased the zeta potential of BN.Then the modified BN?CBN?was prepared via the electrostatic interaction between BN and cation polyacrylamide?CPAM?.The PC composites were fabricated by melt blending.SEM observation and XRD analysis showed that CBN oriented within PC matrix in response to shear force with the restriction of CPAM molecule.As the CBN content increased gradually,the thermal conductivity and thermal stability of composites were improved.At 20 wt%CBN loading,the thermal conductivity of 0.7341 W/?m·K?and the temperature for 5%weight loss?T₅?of 498.6°C were obtained,which was 3.1 times and 77°C higher than that of pure PC,respectively.Meanwhile,the volume and surface resistivity of PC composite remained 10¹⁶?and 10¹⁶?·cm.The interfacial interaction between filler and matrix has an immediate impact on the properties of composites.The cationic polystyrene?c-PS?was synthesized via soap free emulsion polymerization.The strong electrostatic attraction between c-PS particles and BN promoted the adsorption of c-PS on BN.SEM results showed that the interfacial interaction between BN and PC was greatly enhanced and the modified BN?s-BN?was tightly adhered with PC matrix.The thermal conductivity of composites increased with the enhancement of filler contents.At 20 wt%s-BN loading,a thermal conductivity of 0.7003 W/?m·K?was obtained,which was 2.96times as high as that of pure PC.In addition,PC composites retained superior electrical insulation properties.PC composite was a promising material for thermal management and electrical enclosure.