国产小视频91|中文字幕日产乱码六区小草|福利午夜精品|日日噜噜噜噜夜夜爽亚洲精品,国产人免费人成免费视频,在线欧美激情,国内精品伊人久久

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.