Influence of Polyhedral Oligomeric Silsesquioxanes on Thermal and Mechanical Properties of Polycarbonate/POSS Hybrid Composites

Two types of silsesquioxanes were synthesized by hydrolytic condensation reaction, and then were incorporated into polycarbonate (PC) matrix by melt blending to prepare PC/POSS hybrid composites. The study of morphology of the composites showed that octa-phenylsilsesquioxane (PH-POSS) exhibited partial compatibility with PC matrix, while 3-glycidyloxypropylsilsesquioxane (EP-POSS) could react with phenolic hydroxyl groups of matrix. Thermal and mechanical properties were studied by DSC, TGA, and DMA. The result showed that the incorporation of POSS not only improved thermal stabilities of PC composites, but also retarded their thermal degradation. Si-O fractions left during POSS degradations were the key factor governing the formation of a gel network layer on the exterior surface. This layer possessed more compact structures, higher thermal stabilities, and some thermal insulation. In addition, percentage residues at 700 degrees C (C-700) significantly increased from 10.8 to 15.5-22.8% in air. The storage modulus of two series of composites was slightly improved up to 90 degrees C; furthermore, the temperature range of the rubbery state of them shifted to high temperature. POLYM. COMPOS., 32: 1343-1351, 2011. (C) 2011 Society of Plastics Engineers