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Polytetrafluoroethylene ---- performance chapter


Weather resistance

PTFE has very high chemical resistance, for example, in concentrated sulfuric acid, nitric acid, hydrochloric acid, and even boiling in aqua regia, its weight and performance are not changed, and almost insoluble in most solvents, only slightly soluble in full alkane (about 0.1g/100g) above 300 ℃. Polytetrafluoroethylene does not absorb moisture, non-combustible, extremely stable to oxygen and ultraviolet light, so it has excellent weather resistance.

It is worth noting that PTFE cannot withstand extremely strong reducing atmospheres

Molten alkali metal, ammonia alkali solution (alkali metal dissolved in liquid ammonia), some fluoride (such as TFA), naphthalene sodium salt, etc. can quickly corrode PTFE products

Electrical properties

PTFE in a wide range of frequency dielectric constant and dielectric loss are very low, and breakdown voltage, volume resistivity and arc resistance are high.

Radiation resistance

The radiation resistance of polytetrafluoroethylene is poor (104 rads), and degradation is caused by high-energy radiation, and the electrical and mechanical properties of the polymer are significantly reduced.

Polymerization

Polytetrafluoroethylene is produced by the free radical polymerization of tetrafluoroethylene. The industrial polymerization reaction is carried out in the presence of large amounts of water with stirring to disperse the heat of reaction and to facilitate temperature control. Polymerization is generally carried out at 40 to 80°C and 3 to 26 kg force/cm2 pressure, and can be initiated by inorganic peroxides and organic peroxides, or by redox initiation systems. Dispersion polymerization requires the addition of perfluorinated surfactants, such as perfluorooctanoic acid or its salts.

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