Preparation And Properties Of PA6/SiC Thermal Conductive Composites

The thermal conductive materials are widely applied in various fields. In the field of electrical and electronic, materials with high thermal conductivity are needed to help equipment dissipate heat, ensure that device works under appropriate temperatures and prolongs equipment service life. In the motor industry, high thermal conductivity material can can effectively reduce the temperature of the motor winding, increase the power output. In the field of chemical industry, materials used for heat exchanger, not only have high thermal conductivity, chemical resistance and scale resistance. Metal and ceramic used as traditional thermal conductivity materials can not completely meet the application requirements. The thermal-conducting polymer composite has gradually received extensive attention of the researchers, because of its advantages, such as, the good electrical insulation, chemical resistance, fatigue resistance, easy processing etc.In present study, we choose polyamide6(PA6) as matrix and silicon carbide (SiC) as thermal conductive filler to prepare PA6/SiC composites. The PA6is excellent engineering plastic with good mechanical properties and the SiC is of high thermal conductivity. Composites of PA6/SiC is willing to achieve comprehensive performance in both mechanical and thermal conductive properties. The SiC particle size factor that is critical in efficient improvement of thermal conductivity is considered in this study. SiC with various particle size is blended with PA6by melt mixing to prepapare composites. The comprehensive properties of PA6/SiC composites including thermal conductivity, mechanical properties, melting and crystallization behavior, thermal stability and melt flow properties are characterized.For micrometer scale SiC, it is found that with low loading level, less than30%, the PA6/SiC composites with smaller SiC particles shows higher thermal conductivity than that of the composites with larger particles at the same filler content. When the content is higher than30%, the result is just opposite. For nano-SiC, thermal conductive performance of PA6/SiC composites is poor. The results showed that the thermal conductivity of composites was significantly increased to2.2W/mK when the weight proportion of50μm SiC is70%, which is nearly4.9times of that of pure PA6. The tensile strength of PA6/SiC composites, regardless of the size and content, were higher than the tensile strength of PA6. The maximum tensile strength,85.5MPa, is observed for1μm SiC with the content of50%, which is increased by21.3%compared to that of PA6.In order to get better thermal conductivity, silane coupling agent KH-550is used to improves the interfacial adhesion between PA6and SiC. PA6/SiC composites with optimum comprehensive properties are obtained when2%content KH-550is added. The thermal conductivity, tensile strength, breaking elongation, and notched impact strength are increased by15.8%,6.2%,87.0%and68.6%respectively compared to PA6/SiC without KH-550. In addition, the thermal stability of PA6/SiC composites is also improved after addition KH-550.70PA6/30HDPE/SiC composites have also been prepared. Phase structure, thermal conductivity, melting and crystallization behavior and mechanical properties are discussed. It is observed from SEM micrographs that70PA6/30HDPE/SiC composites show sea-island microstructure, and SiC filler specifically distributed in PA6phase; HDPE phase as island structure distributes in the matrix composed of PA6and SiC filler. The thermal conductivity of70PA6/30HDPE/SiC composites are higher than PA6/SiC composites at same content.