Morphology, thermal and mechanical performances of SR composites containing sepiolite and HGMs as binary fillers

Binary fillers-filled silicone rubber (SR) matrix composites are prepared to improve the thermal and mechanical properties of SR as a lightweight thermal insulating material. Sepiolite and hollow glass microspheres (HGMs) can be evenly dispersed in SR matrix to obtain SR/sepiolite/HGM composites with superior performances at amounts of around 7.5 parts per hundreds of rubber (phr) and 20 phr, respectively, as observed from scanning electron microscopy (SEM). The density of the composites increases slightly with the addition of sepiolite in a linear trend, while the addition of HGMs results in the abrupt reduction in density lower than 0.7 g/cm(3). Sepiolite exhibits a strengthening effect in the SR matrix; however, the addition of HGMs in this matrix slightly enhances the stress of the composite; its maximum elongation at break can increase up to 300%. The addition of sepiolite and HGMs improves the initial decomposition temperatures of SR composites a little; the excellent thermal insulating effect provided by HGMs is further verified by their significant decrease in thermal conductivity at 200 degrees C, providing the facts that these SR/sepiolite/HGM composites can be used as lightweight materials for thermal insulating purposes.