Rubber seal is the only polymer material with high flexibility and excellent elasticity. The biggest feature of rubber is firstly that its elastic modulus is very small and its elongation is very high. Secondly, it has quite good resistance to air permeability and resistance to various chemical media and electrical insulation. Some special synthetic rubbers have better oil resistance and temperature resistance, and can resist the swelling of fatty oil, lubricating oil, hydraulic oil, fuel oil and solvent oil; cold resistance can be as low as -60°C to -80°C, and heat-resistant Up to +180°C to +350°C. Rubber is also resistant to various flexures and bending deformations because of low hysteresis loss. The third characteristic of rubber is that it can be used, blended, and compounded with a variety of materials, thereby being modified to obtain good overall performance.