Effect And Mechanism Of Acid Treated Carbon Nanotubes On Thermal Stability Of Silicone Rubber

As an important member of synthetic rubbers,silicone rubber(SR)has many excellent properties among which thermal stability is the one of great application value.In order to make the silicone rubber applicative in more harsh environments and enlarge the application range,SR can be composited with other materials for further improvement of its mechanical and thermal properties.Carbon nanotubes(CNTs)have unique structure and performance,and studies show that CNTs can improve the thermal resistant properties of SR.In this paper,acid treatment of CNTs was adopted,and CNTs with different surface carboxylic group amount were obtained through time control.A series of measurements including Raman spectrum,infrared spectrometry(FTIR),thermogravimetric analysis(TGA)and X-ray photoelectron spectroscopy(XPS)were employed for the characterization of the acid treated CNTs.Then silicone rubber(SR)composite were prepared added with acid treated CNTs.TGA and mechanical performance testing were used to characterize the thermal stability and mechanical properties of the composites.The results indicated that CNTs can improve thermal stability of SR obviously.CNTs with more surface carboxyl groups improved the thermal stability of SR more significantly in air,while graphitized CNTs had a better effect on SR's thermal stability in argon atmosphere.CNTs exhibited positive effect on the mechanical properties of SR as well.What's more,average molecular weight measurement(Mc)as well as thermogravimetric analysis/infrared spectrometry(TG-IR)were employed to study the mechanism of thermal stability improvement.The results indicated that in air,CNTs with more surface carboxyl groups can inhibit the oxidative cross linking,which must be attributed to better dispersion and increased interfacial interaction.In argon atmosphere,graphitized CNTs made the best performance in postponing both the initial degradation temperature and the peak temperature.This can be ascribed to its better thermal conductivity that restrained overheating of specific section.