DYNAMIC-MECHANICAL THERMAL-ANALYSIS ON SURFACE-MODIFIED ALUMINA FILLED ALLYLESTER COMPOSITES

A dynamic mechanical thermal analysis was performed on allylester comp osites filled with alumina. Alumina was treated with various concentra tions of four silane coupling agents. We determined the glass transiti on temperatures and the values of the storage moduli in both the glass y and rubbery states in each system and compared the mechanical-therma l behavior of pristine allylester polymers with that of composites fil led with unmodified or modified alumina. At optimum concentrations of silane coupling agents in each system, the maximum crosslinking reacti on occurred and the maximum glass transition temperature appeared at t he same concentrations by their effective surface coverage. Differenti al scanning calorimetry experiments proved this fact. The order of the glass transition temperatures was 3-aminopropyltriethoxysilane (APS) congruent to vinyltrimethoxysilane (VTS) > 3-methacryloxypropyltrimeth oxysilane (MPS) congruent to (3-glycidoxypropyl)trimethoxysilane (GPS) modified systems because MPS and GPS have flexible ether linkages in their structures but APS and VTS do not. The structures of each silane coupling agent influenced significantly on the glass transition tempe rature, the storage modulus, and tan delta. (C) 1996 John Wiley & Sons , Inc.