Thermal and mechanical properties of SEBS-g-MA based inorganic composite materials

Organic-inorganic hybrids based on a triblock copolymer [polystyrene-b-poly (ethylene-ran-butylene)-b-polystyrene-g-maleic anhydride] (SEBS-g-MA) with silica and clay were prepared using sol-gel and solution intercalation methods respectively. Reinforcement in the first system was achieved by the in-situ hydrolysis/condensation of tetraethoxysilane in the copolymer matrix yielding hybrid materials. The interaction between organic and inorganic phases was developed through a coupling agent. In another system, copolymer was reinforced by organoclay and compatibility between copolymer and hydrophilic montmorillonite was achieved by intercalation of clay with dodecylamine which increased the organophilicity of the clay. Thin transparent films of these hybrids materials were characterized for their mechanical, thermal and thermomechanical behavior. The tensile strength of hybrids improved relative to the pure copolymer in all the systems. Dynamic mechanical thermal analysis carried out gave alpha-relaxation temperature associated with glass transition temperature (T-g). The results indicate a shift in T-g values with the addition of silica in the matrix, which suggests an increased interfacial interaction between organic and inorganic phases while this effect is less pronounced in polymer-clay system. Thermal decomposition temperatures of the hybrids were found in the range of 450-500 degrees C. The weights of the residues left at 700 degrees C were nearly proportional to the inorganic contents in the original hybrids.