The effect of fumed silica on the processing performance of HTV silicone rubber is generally expressed by the degree of structure (∆Crepe), ∆Crepe is equal to the difference between the plasticity value of the compound stored at room temperature for 28 days (p28) and the plasticity value measured immediately after mixing (P0). The plasticity value of the compound is related to the amount of fumed silica, surface properties and structure. The reason for the structure is that the hydroxy group on the surface of fumed silicon dioxide forms a hydrogen bond with the oxygen atom in the silicone rubber and the molecular chain of silicon rubber is adsorbed on the surface of silicon dioxide, which leads to the decrease of the fluidity of the rubber with the extension of time, and the rubber becomes hard, which affects the processing performance. Therefore, in the process of use, it is necessary to add a structural control agent or choose a surface treated fumed silicon dioxide. The addition of a structural control agent and the surface treatment of fumed silicon dioxide react with the silicon hydroxyl group on the surface of silicon dioxide through a structural control machine or surface treatment agent, thereby reducing the number of surface hydroxyl groups and reducing the number of hydrogen bonds formed with silicone rubber. The mixing time of the compound is shortened, the plasticity is increased, and the structuring effect is reduced, and the processing performance and storage stability are improved.

Fumed grade high temperature resistant rubber, plz check MY DI142