What Are The Main Components Of Rubber?

High elastic polymer. Rubber comes from the Indian word cau uchu, which means "tree in tears". Natural rubber is made from the latex that flows out of the rubber tree when it is cut, which is solidified and dried. The molecular chain of rubber can be crosslinked. When the crosslinked rubber is deformed by external force, it has the ability of rapid recovery, good physical and mechanical properties and chemical stability. Rubber is the basic raw material of rubber industry, which is widely used in the manufacture of tire, hose, tape, cable and other rubber products.

Types of rubber are divided into natural rubber and synthetic rubber according to raw materials. According to the shape, it can be divided into block raw rubber, latex, liquid rubber and powder rubber. The latex is a colloidal water dispersion of rubber; Liquid rubber is an oligomer of rubber, which is generally viscous before vulcanization; Powdered rubber is the latex processing into powder, in order to facilitate ingredients and processing. The thermoplastic rubber developed in 1960s is formed by the processing method of thermoplastic without chemical vulcanization. According to the use of rubber is divided into general and special two types.

General purpose rubber has good comprehensive properties and is widely used. There are: ① natural rubber. From the latex of Hevea trifoliata, the basic chemical composition is cis polyisoprene. Good elasticity, high strength and comprehensive performance. ② Isoprene rubber. Its full name is cis-1,4-polyisoprene rubber. High CIS synthetic rubber made from isoprene is also called synthetic natural rubber because its structure and properties are similar to those of natural rubber. ③ Styrene butadiene rubber. SBR is prepared by copolymerization of butadiene and styrene. It is divided into emulsion polymerized styrene butadiene rubber and solution polymerized styrene butadiene rubber according to production methods. Its comprehensive properties and chemical stability are good. ④ Cis-1,4-polybutadiene rubber. The full name is cis-1,4-polybutadiene rubber, abbreviated as BR, which is prepared by polymerization of butadiene. Compared with other general-purpose rubbers, the vulcanized cis-1,4-polybutadiene rubber has excellent cold resistance, wear resistance and elasticity, less heat under dynamic load and good aging resistance. It is easy to be used with natural rubber, chloroprene rubber, nitrile rubber, etc.

Special rubber refers to rubber with some special properties. There are mainly: 1. Chloroprene rubber. Cr is prepared by polymerization of chloroprene. It has good comprehensive performance, oil resistance, fire resistance, oxidation resistance and ozone resistance. But its density is large, it is easy to crystallize and harden at room temperature, and its storage and cold resistance are poor. ② Nitrile rubber. NBR is prepared by copolymerization of butadiene and acrylonitrile. It can be used in air at 120 ℃ or oil at 150 ℃ for a long time. In addition, it also has water resistance, air tightness and excellent bonding performance. ③ Silicone rubber. The main chain is alternately composed of silicon and oxygen atoms with organic groups on the silicon atoms. High and low temperature resistance, ozone resistance, good electrical insulation. ④ Fluororubber. A synthetic rubber containing fluorine atoms in its molecular structure. It is usually expressed by the number of fluorine atoms of fluorine-containing units in the copolymer. For example, fluororubber 23 is a copolymer of vinylidene fluoride and chlorotrifluoroethylene. Fluororubber is resistant to high temperature, oil and chemical corrosion. ⑤ Polysulfide rubber. It is formed by polycondensation of dihaloalkane and alkali metal or alkaline earth metal polysulfide. It has excellent oil resistance and solvent resistance, but its strength is not high, aging resistance and processability are not good, and it has bad smell. It is often used together with NBR. In addition, there are polyurethane rubber, chlorohydrin rubber, acrylate rubber, etc.

The basic process of rubber processing includes plasticizing, mixing, calendering or extrusion, molding and vulcanization. Each process has different requirements for products, and is matched with several auxiliary operations. In order to add all kinds of necessary compounding agents into rubber, raw rubber needs to be plasticized to improve its plasticity; Then, carbon black and various rubber additives are mixed with rubber to form compound; The rubber is extruded into a certain shape blank; Then it is combined with the textile material (or metal material) after calendering and gluing to form semi-finished product; Finally, after vulcanization, the semi-finished product with plasticity is made into the final product with high elasticity.