Study of Surface-Functionalized Nano-SiO2/Polybenzoxazine Composites

A series of the surface-functionalized nanoSiO(2)/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano-SiO2 particles, which were then mixed with benzoxazinc monomers to produce the nano-SiO2-PBOZ nanocomposites. The notched impact strength and the bending strength of the nano-SiO2-PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano-SiO2. At the same load of nano-SiO2, the nano-SiO2-PBOZ nanocomposites exhibit the highest storage modulus and glass-transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO2/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano-SiO2 content and were from 368 degrees C (of the neat PBOZ) to 379 degrees C or 405 degrees C (of the neat PBOZ) to 426 degrees C in air or nitrogen with additional 3 wt % nano-SiO2. The weight residue of the same nano-composite was as high as 50% in nitrogen at 800 degrees C. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1525-1532, 2011