What we usually call "natural rubber" is the solid latex collected from a rubber tree and made by solidifying, drying, and other processes. Natural rubber is a kind of polyisoprene as the main component of natural polymer, the molecular formula is n (C5H8), the rubber hydrocarbon (polyisoprene) content of more than 90%, also contains a small amount of protein, fatty acid, sugar and ash, etc.. Physical characteristics of natural rubber. Natural rubber has high elasticity at room temperature, a plastic, with great mechanical strength, little hysteresis loss, low heat when deformed, therefore the flexing resistance is also very good, and because it is a non-polar rubber, so a good electrical insulation performance. [2] rubber, with plastic, fiber and called the three major synthetic materials, is the only high flexibility and excellent elasticity of high polymer materials. The first characteristic of rubber is that the modulus of elasticity is very small, and the elongation is very high. Second, it has excellent breathability and resistance to a wide variety of chemical and electrical insulation. Some special synthetic rubber has good oil resistance and temperature resistance, resistance to fatty oil, lubricating oil, hydraulic oil, fuel oil and solvent oil swelling; cold can be low to - 60 DEG C to 80 DEG C, heat up to +180 DEG to +350 DEG C. Rubber is also resistant to a variety of bending and bending deformation, because the hysteresis loss is small. The third characteristic of rubber is that it can be used in combination with many materials, blending and compounding so as to obtain good comprehensive properties.