The hydroxyl groups on the surface of silica can easily lead to problems such as easy adsorption of water molecules, poor dispersion, and secondary aggregation, etc., which need to be modified to improve the application performance of silica. Chemical substances that are more likely to react with the hydroxyl groups on the surface of silica can be selected as silica modifiers, among which organic substances are the best:
1. Organosilicon halogen compounds: such as dimethyldichlorosilane and trimethylchlorosilane.
2. Silicone organic compounds: such as polydimethylsiloxane (PDMS), hexamethyldisiloxane (MM), octamethyltrisiloxane (MDM).
3. Alcohol compounds: such as butanol, pentanol, linear heptanol, etc.
4. Silazane compounds: such as hexamethyldisilazane, etc.
5. Organic polymers: such as polyvinyl alcohol.
6. Silane coupling agents: including hexamethyldisilazane, hexamethylethylsilazane, vinylethoxysilane, trimethylethoxysilane, methyltrimethoxysilane, etc.
Among the above, the most common modifier is the silane coupling agent, which improves the interaction between the silica surface and the polymer through chemical modification, weakens the interaction between the filler and the filler, and makes the white carbon Black changes from hydrophilic to hydrophobic, improving its compatibility and bonding with rubber.
Modifier selection requirements:
1. Selection according to product use: it can be selected according to requirements such as dispersibility, PH value, and gloss.
2. Selection according to the modification process: The surface modification process mainly adopts dry method and wet method.
3. Choose according to the price: under the condition of meeting the basic demand of performance, you can choose a cheap modifier to reduce the cost.
4. Select according to the environment: consider the application environment and avoid the use of modifiers that cause environmental pollution.