As a new type of functional material, SAP powder is obviously characterized by strong water absorption, and its water absorption mechanism is more special than ordinary water absorption materials, and its water absorption is stronger than ordinary water absorption materials. This paper briefly introduces the characteristics, water absorption mechanism and synthesis method of super absorbent polymer.
Generally, the maximum water absorption of absorbent materials, such as absorbent cotton and sponge, is only about 20 times its own weight. After the completion of water absorption, the water can be squeezed with the help of external pressure. However, the structure of SAP powder is different from that of general water absorbent materials. The material is a kind of polymer electrolyte with strong water absorption, and the polymer skeleton is distributed in a network.
In nature, there are many substances that can absorb water. According to the different water absorption properties, it can be divided into physical adsorption and chemical adsorption. Among them, physical adsorption is mainly some common adsorption materials, such as paper, cotton and sponge. The water absorption principle of these materials is to absorb water with the help of capillaries. The water absorption effect of these materials is not high, and the maximum water absorption can only be dozens of times its own weight. When heated and pressurized, water will overflow. For chemical water absorption, it combines water with the help of chemical bonds. Due to certain chemical bonds between the molecules of materials and water molecules, water can uniformly penetrate into the network molecular structure. This adsorption method has relatively high firmness, and it is not easy to cause water loss in the heating and pressurized environment. Therefore, it not only has strong water absorption, but also has good water retention. SAP powder is like this.
3.1 Starch
Among the current synthetic methods of SAP powder, the method using starch as raw material is a common method. This synthetic method is mainly through free radical initiated polymerization, followed by ethylene monomer on starch. In this process, mainly through chemical initiation, for some synthesis with special requirements, the method of radiation initiation can be used.
3.2 Cellulose
Because cellulose comes from a wide range of sources, it is easy to obtain and the price is not expensive. In addition, its own properties are easily changed by chemistry, so it is loved by many manufacturers. With the rapid development of science and technology, studying the water absorption of cellulose has become an important topic, which has laid a good foundation for its wide application in the future.
3.3 Synthetic resins
Although synthetic resin started late, it developed rapidly. Since synthetic resin was widely used in Japan, it has also been widely used in western countries. At present, it has become an important research direction. Because there are many kinds of synthetic resins, the research of this material should be further promoted.
To sum up, SAP powder has been widely used and widely concerned in various fields due to its unique characteristics. Understanding the relevant knowledge of super absorbent polymer is conducive to the better application of this material.
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