| With the rapid development of science and technology, a demand for thermal resistant silicone rubber(SR) has increased greatly. A lot of researches focus on the improvement of thermal stability of SR. There are many methods for improving the thermal oxidative stability of silicone rubber. Adding thermal resistant additives into silicone rubber matrix is the most common one.In our previous research, we had found that CNTs and Fe2O3 had a synergetic effect on enhancing thermal oxidative stability of SR. Besides, SnO2 is also a very common thermal resistant additive. The reaction in SnO2/SR is a multi-electron transfer process, while that of Fe2O3/SR is a single electron transfer process. Therefore, whether SnO2 and CNTs have a higher synergy than that of Fe2O3 and CNTs.With the above considerations in mind, high temperature vulcanization SR composites were developed from SR system(including silicone gum, fume silica, curing agent, and so on) with CNTs, SnO2, and SnO2-CNTs, respectively. The synergetic effects of CNTs and SnO2 on the thermal oxidative stability of SR composites were investigated. The results indicated that all kinds of the additives enhanced the thermal oxidative stability of SR and, meanwhile, SnO2-CNTs turned out to be the most effective thermal additive among all the addives.For comparison purposes, both Fe2O3 attached CNTs and TiO2 attached CNTs were prepared and their influences on thermal oxidative stability of SR were also investigated. Interestingly, different synergies between CNTs and metal oxides were found. Both Fe2O3 and SnO2 have positive synergetic effects with CNTs, while a negative synergic effect exists between TiO2 and CNTs. What's more, the action mechanism of SnO2-CNTs on the thermal oxidative degradation of SR composite was studied by X-ray photoelectron spectroscopy(XPS) analyses and thermogravimetric analysis/differential scanning calorimetry(TG-DSC). |
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