Mechanical properties of thermo-oxidative aged silicone rubber thermally stabilized by titanium oxide based fillers

In this work, the mechanical properties of thermo-oxidative aged and thermally stabilized high consistency silicone rubber were investigated. The thermal oxidative stabilization is achieved by titanium oxide based fillers that were incorporated at different concentrations into the silicone compounds. Besides a pure titanium oxide filler, AEROXIDE® TiO2 P25, also an iron oxide doped heat stabilizer, AEROXIDE® TiO2 PF 2, was studied. The addition of the AEROXIDE® TiO2 fillers significantly improves the thermal stability of the compounds and maintains the mechanical properties on a good level after thermal aging. The thermal stabilization depends on the type and concentration of the AEROXIDE® TiO2 fillers. Due to iron oxide doping, the efficiency of AEROXIDE® TiO2 PF 2 is higher in comparison to AEROXIDE® TiO2 P25. However, a too high concentration, especially of AEROXIDE® TiO2 PF 2, induces a catalytic effect and favors the thermal degradation of the silicone. Therefore, the optimum concentration depends on the behavior of the heat stabilizer, its catalytic effect, and the thermal-oxidative conditions applied to the silicone. This study has revealed that titanium oxide based fillers are efficient heat stabilizers to preserve the mechanical properties of silicone rubber on a good level during applications at elevated temperatures.