Effects of BN on the Mechanical and Thermal Properties of PP/BN Composites

In order to explore the thermal conductivity of polypropylene (PP)/hexagonal boron nitride (BN) composites, PP composites filled with different proportions of BN were prepared through extrution compounding, injection moulding and compression moulding. The composites were filled with BN particles of 5 and 20 mu m respectively, and their mass fractions in composites were considered. Percentage of BN was varied from 0 to 25wt% in steps of 5wt%. The effects of BN filler on mechanical properties of the composites were evaluated. The thermal behaviors were studied using DSC and TGA, and the thermal conductivity was also investigated by Laser Flash Device and the Model of 3D Heat Conduction respectively. The experimental results show that impact strength of PP/BN can be enhanced with the addition of BN, but that composites exhibit lower breaking elongation & tensile strength when compared to unfilled ones. It is found that mass fraction of BN influenced the final thermal stability and degree of crystallization of PP matrix, the degree of crystallization of PP with 15wt% of 20 mu m BN can be improved by 25% than neat PP. Meanwhile, crystallization temperatures of PP composites are elevated by about 10 degrees C. The thermal conductivity results demonstrate that the maximum value of the thermal conductivity is achieved from PP/BN with 20wt% of 20 mu m BN, higher than that of pure PP by 95.65%, close to the simulation one.