Polytetrafluoroethylene PTFE air filter membrane performance
Polytetrafluoroethylene PTFE air filtration membrane resin was first developed by American chemist Dr. Plunket in 1938. By the 1950s, industrial production was achieved abroad. In my country, it was formally put into production.
PTFE, commonly known as “PTFE pipe”, is widely used in various aspects because of its unique properties.
It has high temperature resistance, non-oxidation, non-dissolution, particularly good chemical stability and extremely excellent dielectric properties, making it one of the indispensable and important materials in almost all industrial sectors such as chemistry and machinery. .
PTFE air filtration membrane resin is mostly in powder form or dispersion, with extremely high relative molecular mass (8.88×106~3.17×107) and high crystallinity (92%–98%). The melting point is 327°C. The presence of strong F-C bonds in its molecular structure gives it the following main properties: ① Chemical resistance: In addition to being able to react with molten sodium metal, fluorine and strong fluorinated media as well as sodium hydroxide above 300°C, It is inert to almost all commonly used chemicals; ② Heat resistance: no thermal aging occurs below 260°C; ③ Electrical properties: It has good electrical insulation, high arc resistance, and volume resistivity is greater than l×1016Ω. m, and does not change with temperature; ④ Lubricity: low friction coefficient in a wide temperature range; ⑤ Radiation resistance: in vacuum, when the irradiation dose is a maximum value, the original tension can still be maintained 50% of the tensile strength; ⑥ Low permeability: It has low permeability. In addition to its higher permeability to fluorocarbons with similar composition, the PTFE air filtration membrane has less permeability to most gases and liquids. ; ⑦ Weather resistance: not affected by climate, can be exposed to any climate for more than 10 years; ⑧ Non-flammability: limiting oxygen index is above 90; ⑨ Non-stickiness: almost all sticky substances cannot adhere to its surface; ⑩High and low temperature resistance: It can be used within the temperature range of 250~250℃.
PTFE air filter membrane is known as the “King of Plastics” due to its excellent properties and is widely used in various fields such as national defense, aerospace, petrochemicals, electronics, and machinery.
2. Polytetrafluoroethylene resin grade PTFE air filter membranes are available in two types: suspended resin and dispersed resin.
Dispersed PTFE resin has good fiber-forming properties, the molecules are electrically neutral, and the cohesion between particles is low. The molecular chains will be arranged along the long axis of the particles under a small shear effect, forming linear crystals, and sintering molding The final dispersed polytetrafluoroethylene has a greater crystallinity than the suspended polytetrafluoroethylene, and higher strength can be obtained by sintering at a temperature slightly higher than the melting point, such as 340°C to 360°C.
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