Coupling agents can generally be classified into chemical structures: silane coupling agents, titanate coupling agents, and other coupling agents.
In general, the functional groups at both ends of the coupling agent react with the dispersed phase of the filler and the matrix polymer, respectively. Due to different fillers, the coupling effect varies greatly. For example, silane coupling agents have significant effects on silica, alumina, glass fiber, clay, silicates, silicon carbide, etc., on talc, clay, and hydroxide. The effects of aluminum, wollastonite, iron powder, and alumina are slightly worse, and the effects of asbestos, titanium dioxide, and ferric oxide are not so great, and the effects on calcium carbonate, graphite, carbon black, barium sulfate, and calcium sulfate are small. .
Silane-based fillers on the surface, coupling effects of silane coupling agents are large, and for calcium, magnesium, and barium carbonates, sulfates, sulfites, etc., the coupling effect of silane coupling agents is less pronounced . If the silica-based hydrosol is used to treat the surface of filler particles without silanol groups, and then a silane coupling agent is used, a better coupling effect is obtained. This treatment method is called a double coating method.
Both the titanate coupling agent and the aluminate coupling agent can treat the surface of the filler, but the effect of the treatment has a certain degree of specificity. If the titanate coupling agent has better treatment effect, the fillers include calcium carbonate, barium sulfate, calcium sulfate, calcium sulfite, aluminum hydroxide, magnesium hydroxide, calcium silicate, aluminum silicate, titanium dioxide, asbestos, alumina ,Ferric oxide,
Lead oxides, ferrites, etc.; fillers with slightly more effective treatment are mica, silica, magnesia, calcium oxide, etc.; fillers with poor treatment are talc, carbon black, and wood flour; graphite with almost no effect. , magnetic powder, clay, general pigments, etc. However, it must be determined based on the specific type, brand, and dosage of the coupling agent.
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