Study of surface‐functionalized nano‐SiO 2 /polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO 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‐SiO 2 particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO 2 ‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO 2 ‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO 2 . At the same load of nano‐SiO 2 , the nano‐SiO 2 ‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO 2 /PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO 2 content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO 2 . The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011