Fluoroplastics are alkane polymers in which some or all of the hydrogen is substituted by fluorine. They are polytetrafluoroethylene (PTFE) (PTFE), perfluoroethylene-propylene -) (FEP) copolymer, perfluoroalkoxy-(PFA) resin, polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), Ethylene tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride. (PVDF) and (PVF).

A.Trade names "Teflon", "4F" and so on, PTFE is a perfluoropolymer prepared by free radical polymerization of tetrafluoroethylene, which has a linear molecular structure of a CF2=CF2-repeating unit. It is a crystalline polymer with a melting point of about 631 Fahrenheit and a density of 2.13-2.19g/CC (g / cm3). PTFE has excellent chemical resistance, its dielectric constant is 2.1, loss factor is low, and it is stable in a wide range of temperature and frequency. Its mechanical properties range from low temperature to 550 V.

The impact strength of PTFE is high, but its tensile strength, wear resistance and creep resistance are worse than those of other engineering plastics. Glass fiber, bronze, carbon and graphite are sometimes added to improve their special mechanical properties. It has a lower coefficient of friction than almost any other material and has a high oxygen index.

PTFE has a very high melt viscosity, which hinders the use of conventional melt extrusion or molding techniques. The molding and extrusion methods for granular PTFE are similar to those used for powdered metals and ceramics-compression by high-temperature sintering; fine powders are mixed with processing aids (e.g. naphtha) to form a paste and then extruded under high pressure to form thin-walled materials. Reheat to remove volatile processing aids, and finally sintering.

B.PFA is polytetrafluoroethylene modified at temperatures up to 260C, perfluorinated alkoxy resins.

PFA resin is a relatively new melt-processable fluoroplastics.

PFA has a melting point of approximately 580F and a density of 2.13-2.16g/cc (g / cm3). PFA is similar to PTFE and FEP, but has slightly better mechanical properties than FEP, and can be used at temperatures up to 500F above 302C, and has the same chemical resistance as PTEF.

C.PVDF is a high molecular weight polymer of vinylidene fluoride. It is a crystalline material with a melting point of 338 F and a density of 1.78g/CC. Its strength, wear resistance and creep resistance are much higher than those of PTFE, FEP and PFA; it is resistant to most chemicals and solvents, as well as oxidants such as liquid bromine and bromine salt solutions; it has good weather resistance and does not burn in air; Compared with other fluoroplastics, it has a high dielectric constant (8? 9) and loss factor; it has good properties in the temperature range of 148? 302F. PVDF can be made into powdered, granular and dispersed systems (44% resin in dimethyl phthalate and diisobutyl ketone). It can be used for extrusion, injection molding, transfer molding, but also through dry powder or dispersion spraying technology as a coating, semi-finished films, plates, rods and single fiber.

Chemical pump liner made of PTFE,PVDF,PFA material can withstand any corrosive liquid, even high temperature corrosive liquid can withstand.

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