There are about 2000 different plants in the world that can produce polymers similar to natural rubber, and different kinds of rubber have been obtained from 500 of them, but the Brazilian clover tree is really of practical value. When the surface of the rubber tree is cut, the latex tube in the bark is cut off, and latex flows from the tree. The latex collected from the rubber tree is diluted, acid coagulated, washed, compressed, dried, and packed to produce commercially available natural rubber. Natural rubber can be made into cigarette, air dried film, crepe, technical graded dry rubber and concentrated latex according to different rubber making methods. Natural rubber standard rubber or granular rubber is a new type of natural rubber developed in the 1960s. In the past, the development of natural rubber was constrained by the grading and manufacturing methods of conventional cigarette, crepe and air drying products. Therefore, Malaysia began to implement the standard rubber plan in 1965, and developed the production of granular rubber on the basis of the physical and chemical property grading of raw rubber. Standard rubber refers to rubber graded according to physical and chemical performance indicators such as mechanical impurities, plastic retention rate, initial plastic value, nitrogen content, volatile content, ash content, color index, etc. The standard rubber packaging is also relatively advanced. It is generally packaged with polyethylene film and has distinctive marks. The package is light and easy to move. The package weight in Malaysia is 33.3kg, and that in China is 40kg. The grading of standard rubber is relatively scientific, so this grading method was quickly accepted by major natural rubber producing countries and international standardization organizations, and the grading standards for standard rubber were formulated successively. These standards are generally the same, but not completely the same. For example, ISO2000 has five levels, and China's standard GB8081-87 has four levels.
CAS No.: 9006-04-6EINECS No.: 232-689-0 Generally, it is a sheet solid, with a relative density of 0.94, a refractive index of 1.522, an elastic modulus of 2~4MPa, softening at 130~140 ℃, softening at 150~160 ℃, and degradation at 200 ℃. It is highly elastic and slightly plastic at room temperature, and crystallizes and hardens at low temperature. Good alkali resistance, but not strong acid resistance. Insoluble in water, low-grade ketones and alcohols, it can swell in non-polar solvents such as chloroform, carbon tetrachloride, etc.