| Silicone rubber (SR) is an important kind of high performance rubber widelyused in aero-space, information-tech and other fields. Because of its unique structurewith―Si-O‖backbone, silicone rubber has some unique properties compared withother organic rubbers, such as heat resistance, cold resistance, electrical insulation etc.Above all, silicone rubber exhibits excellent thermal stability over other organicrubbers. Attentions have been paid to carbon nanotubes (CNTs) on potentialapplications due to its extraordinary physical, chemical and mechanical properties.Recently, great interests have been shown on CNTs as an additive of polymer due toits advantages of the small size, high aspect ratios, excellent mechanical properties,high thermal conductivity and stability.In this paper, high temperature vulcanized silicone rubber nanocomposites wereprepared by various preparation methods with different structures of CNTs. Theinfluencing factors of CNTs on the thermal stability and thermal conductivity ofsilicone rubber were studied in this paper. We studied the characteristics of CNTs, thedispersion in the SR matrix and the thermal properties of silicone rubber, analyzed theprocess of the degradation, explored the relationship between thermal conductivityand thermal oxidative stability of the composites, and discussed the mechanism of theeffect of CNTs on thermal oxidative stability of silicone rubber.The results indicated that CNTs with a larger aspect ratio improve the thermalconductivity, thermal oxidative stability properties of the composites moresignificantly，surface states make little impact on the thermal conductivity and thermalstability. Composites made by wet method exhibit better dispersion in the polymermatrix, which can improve the thermal properties to larger extent.By analysis of the aging process, it was found that the composites mainly occurdegradation reaction. The addition of carbon nanotubes enhances stability of SR, themain reason is the effect of delay degradation, the initial temperature of the gasproducts and exothermic peak shift to higher temperature. Data analysis showed thatthermal oxidative stability and thermal conductivity are highly related, the derivedformula of thermal degradation also showed that thermal conductivity presentspositive correlation with the degradation temperature. CNTs improved the thermalconductivity of SR, hence enhanced the thermal stability. |
