Abstract:

The effects of silica on mechanical properties, flame retardancy, thermal stability and combustion properties of silicone rubber/silica composites were studied by means of electronic universal testing machine, limiting oxygen index, vertical combustion instrument, synchronous thermal analyzer and cone calorimeter. The results show that the mechanical properties of the composite could be improved significantly with the addition of silica, and the mechanical properties of the composites reach the best while the loading of silica is 40 phrs, the tensile strength is 9.35 MPa, the elongation at break is 614.7%. The flame retardancy of the composites increase with the increase of the addition of silica, and the value of limiting oxygen index of the composite can reach 25.0% while the loading of silica is 50 phrs. The thermal stability of silicone rubber/silica composites are improved significantly with the addition of silica, the initial thermal decomposition temperature and the residual at high temperature of silicone rubber/silica composite with 40 phrs silica are 495.4 ℃ and 31.4%, respectively. The heat release rate, total heat release, total smoke production and carbon dioxide generation of silicone rubber/silica composites are reduced effectively by adding silica, which suggests silica has good flame retardancy and smoke suppression effect on silicone rubber.

Key words: silicone rubber, mechanical properties, flame retardancy, thermal stability, combustion behavior