White carbon black, especially gas phase white carbon black, is the best reinforcing agent for silicone rubber, but there is a problem that hardens the compound rubber, which is generally called "structuring effect". Its structuring increases with the length of time the rubber is parked, and it is even so severe that it cannot be recycled or scrapped. There are two explanations for this, one is that the silicone rubber end group is condensed with the hydroxyl group on the surface of silica; the other is that the silicone rubber silicone chain forms a hydrogen bond with the hydroxyl on the surface of silica.
      There are two ways to prevent structuring. One is to add certain substances that can react with the hydroxyl groups on the surface of silica, such as hydroxy silicone oil, diphenyl silicone glycol, silazane, etc. during mixing. When diphenylsilicondiol is used, it should be treated at 160 ~ 200 ℃ for 0.5 ~ 1h after mixing. This prevents the structure of silica-filled silicone rubber. Another approach is to modify the surface of silica in advance, first remove some surface hydroxyl groups, and fundamentally eliminate structure.