Effective Use of Mesoporous Silica Filler: Comparative Study on Thermal Stability and Transparency of Silicone Rubbers Loaded with Various Kinds of Silica Particles

Four types of silica fillers (nonporous silica particles, mesoporous silica particles, silica gels with micropores, and fumed silica particles) have been used as inorganic filler materials for silicone rubber. To determine their effectiveness as filler materials, a systematic study on the thermal strength and transparency of the obtained silica/silicone composites was conducted. The mesoporous silica/silicone composite shows the lowest thermal expansion and higher transparency than the other composites. The thermal strength and transparency of silica gel/silicone composite is quite similar to those of nonporous silica/silicone composite. Fumed silica/silicone composite is highly transparent (indeed, its transparency is the same as pristine silicone), but the thermal strength is at the same level as nonporous silica/silicone composite. These results clarify that mesoporous silica particles are the most promising filler materials for silicone rubber. A systematic study was conducted on the thermal strength and transparency of four types of silica/silicone composites to determine their effectiveness as filler materials for silicone rubber. Mesoporous silica/silicone composites show the lowest thermal expansion and higher transparency than the other composites, which makes them the most promising filler materials for silicone rubber.