Its friction coefficient is very small, only 1/5 of polyethylene, which is an important feature of perfluorocarbon surface. In addition, due to the extremely low intermolecular forces of the fluorocarbon chain, PTFE is not sticky.
The inner PTFE liner maintains excellent mechanical properties in a wide temperature range from -196°C to 260°C. A characteristic of perfluorocarbon polymers is that they do not become brittle at low temperatures.
Chemical resistance and weather resistance: Except for molten alkali metals, PTFE is hardly corroded by any chemical reagents. For example, when it is boiled in concentrated sulfuric acid, nitric acid, hydrochloric acid or even aqua regia, its weight and properties remain unchanged. It is almost insoluble in all solvents, and only slightly soluble in all alkanes (about 0.1g/100g) above 300°C. Teflon is non-hygroscopic, non-flammable, and extremely stable to oxygen and ultraviolet rays, so it has excellent weather resistance.
Electrical characteristics: The dielectric constant and dielectric loss of PTFE lining are lower in a wide frequency range, and the breakdown voltage, volume resistivity and arc resistance are higher.
Radiation resistance: The PTFE lining has poor radiation resistance (104rad) and is degraded by high-energy radiation. The electrical and mechanical properties of the polymer are significantly reduced.
Polymerization: The PTFE lining is made of free radical polymerization of tetrafluoroethylene. Industrial polymerization is carried out by stirring in the presence of a large amount of water, which is used to disperse the heat of reaction and facilitate temperature control. The polymerization is generally carried out at 40~80℃ and 3~26kgf/cm~2. Inorganic persulfates and organic peroxides can be used as initiators, and redox initiator systems can also be used. The heat released per mole of tetrafluoroethylene is 171.38 kJ. Dispersion polymerization requires the addition of perfluorosurfactants, such as perfluorooctanoic acid or its salts.