In addition to the general requirements of the sealing ring material, the sealing ring should also pay attention to the following conditions:
（1） Full of elasticity and resilience;
（2） Appropriate mechanical strength, including expansion strength, elongation and tear strength, etc.
（3） The performance is stable, it is not easy to swell in the medium, and the thermal shrinkage effect （Joule effect） is small.
（4） Easy to process and shape, and can maintain precise dimensions.