Reinforcement property of structural silicon sealant as a function of the size and loading of nano CaCO 3 particles has been investigated by mechanical measurement and DMA experiments. The tensile strength and elongation at break of silicone sealant were found greatly enhanced by nano CaCO 3 particles. The smaller the particle size, the higher the tensile strength and the elongation will be. The storage modulus is also remarkably increased with the increasing of CaCO 3 loading and decreasing of CaCO 3 particle sizes, as revealed by DAM. Two relaxation peaks are seen for silicon sealant. One is around 153 K, corresponding to the glass transition temperature(T g), and the other is around 233 K, corresponding to the melting temperature(T m). Both T g and T m increase with the increasing of CaCO 3 loading and decreasing of CaCO 3 particle sizes. DMA results suggest that the interaction between nano CaCO 3 particles and silicon sealant is quite strong. The molecular motion of silicon sealant is highly limited by the dispersed nano CaCO 3 particles.
