(1) Modification of silane coupling agent Using the double reaction function of silane coupling agent, one end of the organic group reacts with the hydroxyl group on the surface of silica, and the other end reacts with the polymer macromolecular chain such as rubber, so that the surface characteristics of silica can be changed. Generally speaking, silane coupling agents commonly used in rubber industry are divided into silane coupling agents containing sulfur, such as Si69 and Si75, and silane coupling agents without sulfur. Sulphuric-containing silane coupling agent was grafted on the surface of silica, and further interacted with the rubber molecular chain through the action of sulfur and vulcanization accelerator at high temperature during the vulcanization process. Sulphur-free silane coupling agents have an alkoxy group at one end and a double bond group, an epoxy group, or an amino group at the other end that has a good affinity with the rubber molecular chain.
(2) Modified by alcohol ester method. On the surface of silica, fatty alcohol reacts with silica hydroxyl group to remove water molecules, and silica hydroxyl group is replaced by alkoxy group, so that the surface properties of silica black change.
(3) Polymer grafting modification Polymer grafting modification refers to the chemical reaction under certain conditions, the polymer grafting to the surface of silica.
(4) Polymer coating modification is a commonly used surface modification technology, that is, the surface of silica covered with a layer of different chemical composition of the coating layer, so as to reduce the interaction between hydroxyl groups, ultimately reduce the surface energy, improve the dispersion.
In addition to the above surface modification methods, silica can also be modified by emulsion polymerization, inorganic surface coating modification, and ultrasonic modification.