Chemical corrosion and weather resistance: Except for molten alkali metals, PTFE is almost not corroded by any chemical reagents.
For example, when boiled in concentrated sulfuric acid, nitric acid, hydrochloric acid, or even aqua regia, its weight and performance remain unchanged. It is also almost insoluble in all solvents, and is only slightly soluble in all alkanes above 300°C (about 0.1g/100g ).
PTFE does not absorb moisture, is non-flammable, and is extremely stable to oxygen and ultraviolet rays, so it has excellent weather resistance.
Although the breaking of carbon-carbon bonds and carbon-fluorine bonds in perfluorocarbons requires energy absorption of 346.94 and 484.88kJ/mol respectively, the depolymerization of polytetrafluoroethylene to generate 1 mol of tetrafluoroethylene requires only 171.38kJ of energy.
So during high temperature cracking, polytetrafluoroethylene mainly depolymerizes into tetrafluoroethylene.
The weight loss rates (%) of polytetrafluoroethylene at 260, 370 and 420°C are 1×10-4, 4×10-3 and 9×10-2 per hour respectively.
It can be seen that PTFE can be used for a long time at 260℃.
Since highly toxic by-products such as fluorophosgene and perfluoroisobutylene are also produced during high-temperature cracking, special attention must be paid to safety protection and to prevent polytetrafluoroethylene from coming into contact with open flames.
It does not melt at a temperature of 250°C and does not become brittle at an ultra-low temperature of -260°C.
Polytetrafluoroethylene is extremely smooth, even ice cannot compare with it; its insulation properties are very good, a film as thick as newspaper is enough to withstand high voltage of 1500V.
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