A light yellow amorphous substance with the molecular formula of (C5H8)n is an elastic polymer compound. Produced from rubber plants such as rubber trees, the main component is polyisoprene, in which cis-1, 4- isoprene is 98% ~ 100% and cis-3,4-isoprene is 0 ~ 2%; The degree of unsaturation is 95% ~ 98.5%; The molecular weight is1* 05 ~ 4 * 06; Mooney viscosity is high, it becomes hard when stored, easy to crystallize at low temperature and brittle at about -70℃. Without a certain melting point, it completely softens when heated to 130 ~ 140℃ and begins to decompose at around 200℃. The elasticity is very good, the elastic modulus is 3 ~ 6 MPa, and the elastic elongation can reach 1000%. Good processability, easy to mix with fillers and compounding agents, and can be used with most synthetic rubbers; Non-polar rubber swells in non-polar solvents and has poor oil resistance and solvent resistance; Containing a large number of unsaturated double bonds, it has high chemical activity, easy cross-linking and oxidation, and good aging resistance. It has the characteristics of strong elasticity, good insulation, strong plasticity, water resistance and gas resistance, and high tensile strength. After proper treatment, it has excellent properties such as oil resistance, acid resistance, alkali resistance, heat resistance, cold resistance, pressure resistance and wear resistance. Widely used in transportation, medical and health care, machinery manufacturing, aerospace and other fields and daily life, including more than 70,000 kinds of daily necessities, which are important industrial raw materials.