The first is the chemical structural difference:
PFA is added to perfluoroalkoxy, which is equivalent to a fluorine atom in PTFE replaced by perfluoroalkoxy. One carbon is connected directly to the oxygen, and then the oxygen is bonded to a perfluoromethyl or perfluoroethyl group. Compared with PTFE, the melting viscosity is favorable for machining. The rest of the properties are not much different from PTFE.
The second difference is the application:
PFA-- with the same excellent properties of ptfe, and with good thermoplastic, thermoplastic process can be made by the processing method of ordinary thermoplastic resin. Tetrafluoroethylene and perfluoropropyl vinyl ether have a certain proportion in the water medium containing perfluorocarbon acid salt dispersant, persulfate initiator, and the white translucent granule. Not only has the same temperature, as the teflon and have better mechanical strength at 250 ℃ (about 2 ~ 3 times), and stress cracking resistance is good. Its processing range is wide, the molding performance is good, suitable for pressing plastic, extrusion, injection molding, transfer molding processing. It can make wire and cable insulation sheath, high frequency and ultra-high frequency insulation parts, chemical pipe, valve and pump corrosion resistant lining; The machine industry USES special spare parts, textile industry to use various anticorrosive materials, polytetrafluoroethylene anti-corrosion lining and other welding rods. Made of fusible teflon granules, the appearance is translucent milky white, smooth surface and uniform section. It is specially designed for the welding of teflon board and tube, making teflon shape simple products, welding into a complex shape and large size. The aqueous dispersion is a copolymer obtained by copolymerization of teflon and perfluoropropyl vinyl ether copolymer, which is concentrated at a certain temperature. The solid content is 30% plus or minus 1%. The appearance is milky white or light yellow translucent. All kinds of excellent properties of fusible ptfe resin. Can use for a long time under 260 ℃, and with its excellent sticking prevention, anti-corrosion, easy processing performance development into advanced coating, spraying, dipping, are widely used in copying technology and the food industry as a sticking prevention, anti-corrosion materials.
PTFE- polytetrafluoroethylene is made from tetrafluoroethylene monomers using suspension or dispersion polymerization. The molecular weight is equal to 5. 2 x 105-4. 5 x 107. White powder, the 400 aim is 75%, tasteless, not beautiful, non-toxic. Relative density 2. 1 to 2. 3. Refractive index 1. 37, the glass transition temperature of 327 ℃, the thermal decomposition temperature of 415 ℃. Trace weightlessness at above 400 ℃ and decomposition of the toxic gas. Use temperature - 250 ~ 260 ℃, 210 ℃ in the use of up to 10000 h. Excellent chemical resistance, resistant to any strong acid (including wang shui), strong alkali, grease, insoluble in any solvent, low friction coefficient, good wear resistance, and self-lubricating. Good aging resistance. Excellent electrical performance, good arc resistance. With nonviscous, almost all viscous matter can't adhere to its surface, completely nonflammable. There is the "plastic king". Tensile strength (MPa) > 23 elongation (%) > 250.
Again, the difference in processing: