Currently for the requirements of high corrosion resistance and using temperature more then 100 degree, the sealing elements mostly choose PTFE or filled PTFE, this is mainly because PTFE has the performance such as good chemical resistance, ageing resistance, low friction coefficient, wide usage temperature range, no-stick and so on. Mechanical properties of PTFE influence significantly by the temperature and load.

　　The PTFE compression modulus, compression stress and tensile stress changes due to the temperature level, It under different compression and tensile stress strain also change accordingly, its compression deformation varies with the temperature and load.

　　PTFE crystallization volume increase 0.0058cm3/g in the 19℃, equivalent to increase 1.2% volume, so its linear expansion coefficient sudden increase in the temperature of 19℃, and at 30℃ is another turning point, volume change is 10%.

　　The linear expansion coefficient of the filled PTFE has a direction, in parallel to the direction of the preforming pressure linear expansion coefficient is higher than the linear expansion coefficient of perpendicular to the direction of preforming pressure, the former is about 40% higher than the latter.