The side groups on the silicone main chain can be methyl, ethyl, vinyl, phenyl, trifluoropropyl and so on. Methyl groups are most commonly used, but other groups can also be introduced to improve processing properties and other properties. Therefore, depending on the side base groups and sizing formula, can get all kinds of different USES silica gel, generally can be divided into the following several types: general type (including methyl and vinyl), high temperature and low temperature type (including phenyl methyl and vinyl), low compression permanent deformation (including methyl and vinyl), low shrinkage (volatile) and resistance to solvent (fluorine silicone), etc. Several important types of silica gel are described below.
1. Dimethyl silica gel dimethyl silica gel is one of the earliest silica gel put into commercial production, which can maintain good elasticity in the range of -60 ~ 200℃, good aging resistance, excellent electrical insulation properties and moisture-proof, shockproof and physiological inertia. Dimethyl silica gel is mainly used for fabric coating, but also can be made into a variety of extrusion and calendering products used in electromechanical, aviation, automobile and medical industries. But because the dimethyl silica gel vulcanization activity is low, used for the manufacture of thick products, vulcanization is difficult, the inner layer is easy to bubble and high temperature compression permanent deformation, so it has been replaced by methyl vinyl silica gel.