Improved thermal oxidative aging resistance of silicone rubber via incorporation with Fe-MOFs

Under harsh service conditions, room temperature vulcanized silicone rubber (RTV) is required to exhibit excellent thermal-oxidative aging resistance while maintaining its mechanical performance. To meet this demand, iron-based metal–organic frameworks (Fe-MOFs) were synthesized and incorporated into the RTV matrix. The influence of three different fillers — Fe-MOFs, graphene, and Fe-MOFs/graphene — on the thermal oxidative stability and mechanical properties of RTV was systematically investigated and compared. Low-field nuclear magnetic resonance (LF-NMR) was employed to probe the evolution of crosslink density at the molecular level during thermal-oxidative aging, while the thermal degradation behavior was comprehensively characterized using thermogravimetric analysis coupled with differential scanning calorimetry (TGA/DSC)-FTIR. The results revealed that Fe-MOFs can elevate the thermal decomposition temperature of RTV silicone rubber by 42 °C, while simultaneously enhancing its tensile strength by 1.7 times and increasing its elongation at break by 14.6%. During the thermal oxidative aging process, Fe-MOFs effectively suppress the premature degradation of RTV and the associated deterioration of mechanical properties. This protective effect is primarily attributed to two factors: first, Fe-MOFs increase the crosslinking density of RTV by 13.6%; second, the organic framework structure of Fe-MOFs efficiently scavenges free radicals, thereby retarding the progression of oxidative reactions. • Fe-MOFs enhance the anti-thermal-oxidation aging performance of RTV by capturing free radicals. • Fe-MOFs can adjust the crosslinking density of RTV, thereby improving its mechanical properties. • 3% Fe-MOFs elevated the thermal decomposition temperature of RTV by 42 °C. • 3% Fe-MOFs enhanced RTV’s tensile strength by 1.5 times.