Effect And Mechanism Of Copper Oxide Modified Carbon Nanotubes On Thermal Stability Of Silicone Rubber

Silicone rubber(SR),as one of the most important types of high performance rubbers,is widely used under high temperature environment due to its excellent thermal stability.Recently,many researches focus on the improvement of thermal stability of SR.Among the methods to improve the thermal stability of SR,adding thermal resistant additives into SR matrix is the most common one.In our previous research,it has proved that carbon nanotubes(CNTs)and iron oxide had a synergetic effect on enhancing thermal stability of SR.It still needs to be further studied if the synergetic effect between CNTs and metal oxides is fortuitous or universal.Copper oxide(CuO),as an important semiconducting material,has a very extensive application.In the past few years,several researches focused on the thermal properties of CuO/polymer have emerged.Therefore,CuO was chosen in this study.To investigate the effects of CNTs and CuO on the thermal stability of SR,CuO and CuO modified CNTs(CuO-CNTs)were synthesized by sol-gel method and then introduced into SR matrix to prepare nanocomposites.The results of tensile testing before and after aging and thermogravimetric(TG)analysis under different atmospheres indicated that under air atmosphere,all the nanoparticles could improve the thermal stability of SR at the oxidation degradation stage of side groups and the CuO-CNTs/SR had the best thermal stability,which demonstrated that CuO-CNTs had synergetic effect.Under argon,CNTs could increase the thermal stability of SR main chain while the Cu O and CuO-CNTs decreased it.X-ray photoelectron spectroscopy(XPS)analyses and thermogravimetric analysis/infrared spectrometry(TG-IR)were used to investigate the action mechanism of CNTs and CuO during the thermal degradation process of SR.The results indicated that CuO could capture the free radicals generated by the thermal oxidative reaction of the methyl side groups and thus improved the thermal stability of SR.The synergistic effect of CuO-CNTs was mainly proposed to include that the CNTs had excellent thermal conductivity and CNTs and CuO could promote each other to capture the free radicals.Under argon,CuO and CuO-CNTs decreased the formation temperatures of degradation products of the SR main chain and increased the concentrations of the products.This phenomenon might be ascribed to a kind of radicals generated by CuO which could accelerate the main chain scission reaction.