Fillers play important roles in the performances of silicone rubber, such as mechanical and physical properties. In this paper, the silicone rubber filled with silica in a wide volume range was measured in order to study the effects of filler loading on the mechanical properties of silicone rubber. The composites samples added with surface treated silica filler was characterized by Scanning Electron Microscopy (SEM) and fluorescent microscope with that reinforced by the unmodified filler as a comparison. The results showed that the surface treated filler are more easily diffused without agglomerate in the polymer network compared to the unmodifiedd filler. Incorporation of modified filler loading leads to the increase in both tensile strength and the elongation at break, but along with further increase in filler content, mechanical properties of silicone rubber decreased due to the filler particles aggregate state, which can be observed by SEM images. The tack-free time and the hardness of the silicone rubber decrease as the filler loading increases.

Additives are always added into silicone rubber to improve properties. As a sealant, it is well known that the adhesion property is a key aspect of the sealant system. The effect of additives on the adhesion properties of silicone rubber sealant are discussed in this study. The results showed that the adhesive properties of samples with single coupling agent are lower than that with multiple coupling agents. The adhesive properties of sample first increase with increasing amount of coupling agent and then decrease linearly. The adhesion strength of SR sealant decreased with the amount of the plasticizer and filler added into the silicone rubber has little influence on the adhesion strength of silicone rubber.