As a filler of polymer materials, microsilica powder can not only reduce the production cost of composite materials, but also endow materials with more excellent properties, such as improving wear resistance, acid and alkali resistance, high temperature resistance, insulation, mechanical strength and low expansion rate, etc. Broad development prospects.
Surface modification is one of the key processing technologies for the application of silicon micropowder in polymer materials. Organic modification is a method that uses functional groups in organic matter to perform physical adsorption, chemical adsorption and chemical reactions on the surface of silicon micropowder to change the surface properties of silicon micropowder. , is the most commonly used modification method of silica powder.
At present, the most commonly used organic modifiers for silica powder are silane coupling agents, mainly including amino groups, epoxy groups, vinyl groups, sulfur groups, etc. The modification effect is usually good, but the price is expensive. Some researchers use relatively cheap modifiers such as aluminate, titanate, and stearic acid to modify silicon micropowder, but the modification effect is often inferior to that of silane coupling agents. Therefore, combining economic benefits and modification effects, using Composite modification of silicon micropowder by two or more surface modifiers is often more ideal than using a single modifier.
The screening of microsilica powder surface modifiers needs to be determined according to the properties and uses of the base material of the filler material, the structure, properties, and mechanism of action of the modifier. The mechanism of action of commonly used organic modifiers on the surface of microsilica powder Summarized as follows.
1. Modification mechanism of silane coupling agent
The most commonly used organic modifier for surface modification of silica powder is silane coupling agent, which is a low-molecular-weight organosilicon compound containing two or more different chemical properties, and its molecular structure contains functional groups that interact with organic polymers. (such as amino groups, vinyl groups, epoxy groups, etc.) and alkoxy groups that can be hydrolyzed and interact with the surface of the silica powder can tightly combine the silica powder with the organic polymer.
2. Modification mechanism of titanate coupling agent
The main mechanism of action between the titanate coupling agent and the silica powder is that the inorganic group (RO) m in the titanate molecular structure reacts chemically with the hydroxyl group on the surface of the silica powder, forming a monomolecular layer on the surface of the silica powder, and releasing isopropanol.