What is the difference between soluble polytetrafluoroethylene (PFA) and polytetrafluoroethylene (PTFE)

Soluble polytetrafluoroethylene (PFA) is soluble polytetrafluoroethylene, high-temperature fusion material with fluidity, mainly used for injection molding chemical parts, the use of temperature is generally within 220.

Polytetrafluoroethylene (PTFE) material high-temperature fusion does not have fluidity, not using injection molding process production, generally using molding, or push pressure and other processes, mainly for chemical or mechanical parts, the use of temperature in -180 + 260 degrees, modified polytetrafluoroethylene use temperature can be close to 280 degrees.

First is the chemical structure difference.

PFA added perfluorinated alkoxy, equivalent to PTFE in a fluorine atom is replaced by perfluorinated alkoxy. A carbon is directly connected to an oxygen, and then the oxygen is connected to a group like perfluoromethyl or perfluorooctyl. Compared to PTFE, this reduces the melt viscosity and facilitates processing. The rest of the properties are not too much different from PTFE.

Next is the difference in application: PFA - has the same excellent performance of polytetrafluoroethylene, and has good thermoplasticity, available for thermoplastic processing methods of ordinary thermoplastic resin. It is made by copolymerization of tetrafluoroethylene and perfluoropropyl vinyl ether in a certain ratio in aqueous medium containing perfluorocarboxylate dispersant and persulfate initiator, and is seen as white translucent particles.

Not only has the same temperature as PTFE, but also has better mechanical strength at 250℃ (about 2~3 times), and excellent stress cracking resistance. Its processing range is wide, molding performance is good, suitable for compression molding, extrusion, injection molding, transfer molding and other molding processing. It can make wire and cable insulation sheath, high-frequency and ultra-high-frequency insulation parts, chemical pipeline, valve and pump corrosion-resistant lining; special spare parts for machinery industry, various anti-corrosion materials for light textile industry, PTFE anti-corrosion lining and other welding rods.

Extruded from fusible Teflon granules, its appearance is translucent milky white, smooth surface, dense and uniform cross-section. It is specially used for welding of Teflon plates and tubes, so that Teflon products with simple shapes can be welded into parts with complex shapes and large sizes.

The water dispersion is obtained by adding emulsifier to the copolymer obtained by copolymerization reaction of tetrafluoroethylene and perfluoropropyl vinyl ether, and concentrated at a certain temperature. The solid content is 30%±1%. The appearance is milky white or light yellow translucent. It has all the excellent properties of fusible PTFE resin. It can be used for a long time at 260℃ and developed into an advanced coating with its excellent anti-adhesive, anti-corrosion and easy processing properties, which can be sprayed and impregnated, and is used in a large number of applications in copy technology and food industry as anti-adhesive and anti-corrosion materials.

PTFE - polytetrafluoroethylene is produced by the polymerization of tetrafluoroethylene monomer by suspension or dispersion method. Molecular weight = 5.2×105-4.5×107. White powder, 75% of the 400 purpose, tasteless, non-beautiful, non-toxic. Relative density 2.1-2.3, refractive index 1.37, glass transition temperature 327℃, thermal decomposition temperature 415℃. There is a slight weight loss and decomposition of toxic gas above 400℃.

Excellent chemical resistance, resistant to any strong acid (including aqua regia), strong alkali, grease, insoluble in any solvent, very low coefficient of friction, good wear resistance, and self-lubricating. Excellent aging resistance. Excellent electrical properties, good arc resistance. Non-stick, almost all sticky substances can not adhere to its surface, completely non-combustibility. It has the name of "King of Plastics". Tensile strength (MPa) > 23 Elongation (%) > 250.

The main difference of processing method is that PFA can be processed by hot-melt injection molding, while PTFE cannot be processed by hot-melt injection molding.