Cure of unsaturated polyester resins with solutions of styrene and silsesquioxanes containing methacrylic groups

Silsesquioxanes represent polyhedral structures that can be described by a generic formula (RSiO1,5)(n) or T-n. Methacryloxypropyl trimethoxysilane was hydrolytically condensed in the bulk, with 98% formic acid used as catalyst, to yield a silsesquioxane containing methacrylic groups (SSQO) that was characterized by a distribution of incompletely condensed cubes and their dimers and trimers. Styrene (S) solutions of SSQO were used as crosslinking monomers of unsaturated polyesters (UP). The subsequent cure, initiated by benzoyl peroxide, was characterized by a high conversion of double bonds as revealed by the reaction heat measured by differential scanning calorimetry. The resultant cured materials exhibited different mechanical properties dependent on the amount of SSQO in the initial formulation. Addition of SSQO resulted in enhanced resistance to thermal degradation.