Cure Characteristics, Mechanical and Thermal Properties of Al₂O₃and ZnO Reinforced Silicone Rubber

The effects of alumina (Al2O3) and zinc oxide (ZnO) fillers on the curing characteristics, thermal and mechanical properties of silicone rubber were studied. Rheometer results indicate that the incorporation of ZnO fillers retards the curing process, whereas an enhancement in cure rate was observed for Al2O3. Higher maximum torque (MH) and minimum torque (ML) values was also observed for ZnO silicone rubber compounds compared to Al2O3. Thermogravimetric analysis (TGA) showed that ZnO silicone rubber compounds are thermally more stable than Al2O3; however, the coefficient of thermal expansion of the Al2O3 silicone rubber compounds are lower than that of ZnO. Comparison in mechanical strength between the two silicone rubber hybrids indicates that ZnO is a better reinforcement filler, as evidenced in the tensile strength, elongation at break, and modulus at 300% elongation.