人妻aⅴ中文字幕无码_老熟妇仑乱视频一区二区_午夜精品久久久久久久无码_亚洲精品国产成人 久久久久久88色偷偷,久久久久久精品免费免费,久久天天拍天天爱天天躁,精品久久久久久久久

The tetrafluoroethylene material can be used for a long time at -180～260oC. This material is resistant to acid, alkali and various organic solvents, and it is almost insoluble in all solvents. At the same time, polytetrafluoroethylene has the characteristics of high temperature resistance, its friction coefficient is extremely low, and it does not stick to the reaction medium. Therefore, it is widely used in reaction materials that cannot be tolerated by metal materials.