(1) Coupling modification is a chemical coupling reaction on the particle surface, and the particle surface can have good compatibility with organic substances after being treated with a coupling agent. Shi Weixian et al. used silane coupling agent KH-570 to modify the surface of magnetic Fe3O4, and further analyzed and characterized the magnetic composite particles. The Fe3O4 magnetic particles were treated with silane coupling agent KH-550; the surface characteristics of the modified particles were detected by scanning electron microscope. The results show that both Fe3O4 and modified Fe3O4 particles have irregular shapes, but the dispersibility of the modified Fe3O4 particles is significantly better than that of the unmodified Fe3O4 particles, which is because the coupling agent on the surface of the particles prevents the agglomeration of Fe3O4 particles. The particle size test results of Fe3O4 and modified Fe3O4 show that the modified Fe3O4 has larger specific surface area and smaller particle size.
The application of silane coupling agent as surface modifier in metal anticorrosion pretreatment is its latest application. In order to obtain a good anti-corrosion coating combined with the metal substrate, it is necessary to select a suitable coating system, formulate a reasonable coating process, and carry out strict surface pretreatment.
There are 2 methods for surface pretreatment:
①The plasma polymerization method is used to deposit an organic thin film on the metal surface, but the high cost of this method limits its popularization and application;
②Using an aqueous solution of organic silane coupling agent to deposit a thin layer of organic silane film on the metal surface. Since the silane coupling agent can form trihydroxy silanols after hydrolysis, the alcoholic hydroxyl groups can react with each other to form a cross-linked dense network hydrophobic film, because the surface of this film has organic functional groups that can react with the resin. Therefore, the adhesion of the paint film will be greatly improved, and the ability of anti-corrosion, anti-friction and impact resistance will also be improved.
(2) In the process of plastic research and production, a large number of inexpensive inorganic fillers (or reinforcing agents) are usually used. This not only increases the quality of the plastic and reduces the cost of the product, but also improves certain properties of the plastic product. However, due to the significant differences in chemical structure and physical form between inorganic fillers and organic polymers, the lack of affinity between the two often affects the mechanical properties and molding processability of plastic products. Through the chemical reaction or physical coating of the coupling agent and the inorganic filler, the surface of the filler is changed from hydrophilic to lipophilic, so as to achieve a close bond with the polymer, and improve the strength, adhesion, electrical properties, hydrophobicity of the material. The performance and anti-aging performance are significantly improved.
Some people have used various silane coupling agents to treat the glass fiber surface. The results show that the coupling agent containing amino group has better surface treatment effect on glass fiber than the coupling agent without amino group, because the amino group of the coupling agent and additives And the amino group in the matrix has affinity, coupled with the cross-linking auxiliaries, so that the interface of the composite material has good adhesion, but there is no such function without the amino group; the amino group can also interact with the grafted The acid anhydride functional group reacts to generate chemical bonds across the interface, which improves the bonding strength of the interface and improves the overall performance of the composite material.
The coupling agent has 2 groups with different properties. The inorganic-philic group can react with chemical groups on the surface of inorganic substances (such as glass, fly ash and other silicon-containing materials) to form strong chemical bonds; It can react with organic molecules or physically entangle, so that the interface between organic and inorganic materials can be chemically bonded, and the bonding strength can be greatly improved.