Fluoroplastics are paraffinic polymers in which some or all of the hydrogen is replaced by fluorine. They are polytetrafluoroethylene (PTFE), perfluoro(ethylene propylene) (FEP) copolymers, polyperfluoroalkoxy (PFA) resins, poly Chlorotrifluoroethylene (PCTFF), ethylene-chlorotrifluoroethylene copolymer (ECTFE), ethylene-tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride (PVDF) and polyvinyl chloride (PVF).

PTFE

The trade names are "Teflon", "Teflon", "Teflon", "Teflon", "4F", etc. PTFE is a perfluoropolymer obtained by free radical polymerization of tetrafluoroethylene. It has a linear molecular structure of a C Ma-CFZ-repeating unit, and is a crystalline polymer with a melting point of about 631° C. and a density of 2.13-2.19 g/cC (grams/cubic centimeter). PTFE has excellent chemical resistance, has a dielectric constant of 2.1, has a low dissipation factor, and is stable over a wide temperature and frequency range. It has good mechanical properties from low temperature to 550V.

PTPE has high impact strength, but its tensile strength, wear resistance and creep resistance are worse than other engineering plastics. Glass fibers, 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 can be made into pellets, coagulated fines (0.2 microns) and aqueous dispersions. Granular resins are used for compression molding and plunger extrusion; fine powders can be paste-extruded into thin-walled materials; dispersions can be used as coatings and impregnated porous materials. The pure PTEE products distributed in the American market include AI-goflo brand of Auimont USA, Teflon brand of DU POut company, FI brand of ICI AInericas Inc, and HOSaflon brand of HOechstCelanese company.

PTFE has a very high melt viscosity, which prevents the adoption of conventional melt extrusion or molding techniques. The molding and extrusion methods of granular PTFE are similar to those used for powdered metals and ceramics - first compression and then high temperature sintering; fine powder needs to be mixed with processing auxiliary materials (such as naphtha) to form a paste, and then extruded under high pressure. Thin-walled material, reheated to remove volatile processing aids, and finally sintered.

Polyperfluoroethylene propylene

FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene.

FEP has a crystalline melting point of 580°F and a density of 2.15g/CC (grams per cubic centimeter). It is a soft plastic with lower tensile strength, abrasion resistance and creep resistance than many engineering plastics. It is chemically inert and has a low dielectric constant (2.1) over a wide temperature and frequency range. The material does not ignite and prevents the spread of flames. It has excellent weatherability, a low coefficient of friction, and can be used from low temperatures to 392°F. The material can be made into granular products for extrusion and molding, as a powder for fluidized beds and electrostatic finishing, and as an aqueous dispersion. Semi-finished products include films and boards. Rods and monofilaments. The FEPs distributed in the US market include Teflon from DUIPont, Neoflo from Daikin, and IHoustaflow from Hoechst Celanese at www.seafar.cn. Its main use is to make pipes and chemical equipment, the surface layer of drums and various wires and cables, such as aircraft hook lines, booster cables, alarm cables, flat cables and oil well logging cables. FEP films have been seen as thin coatings for solar collectors.

Soluble PTFE

PFA is polytetrafluoroethylene modified, the temperature can reach 260 degrees, perfluoroalkoxy resin

PFA resins are relatively new melt-processable fluoroplastics.

PFA has a melting point of approximately 580°F and a density of 2.13-2.16g/cc (grams per cubic centimeter). PFA is similar to PTFE and FEP, but has slightly better mechanical properties than FEP above 302°C, can be used at temperatures up to 500°F, and has comparable chemical resistance to PTFE. The product forms of PFA are granular products for molding and extrusion, powder products for rotational molding and coatings; its semi-finished products are films, sheets, rods and pipes. The PFA resins distributed in the US market include Teflon brand of DUPOut Company, Neoflon brand of Daikin Company, Hthen brand of Ansimont Company, and Hostafl brand of HOechst Celanese Company. The use of PFA is similar to that of FEP.

Polychlorotrifluoroethylene

PCTFE is a product of chlorotrifluoroethylene radical-initiated polymerization with a linear main chain mainly repeating a CF(cl)-CF unit.

PCTFE is a crystalline polymer with a melting point of 425°F and a density of 2.13g/cc (grams per cubic centimeter).

PCTFE is inert to most active chemicals at room temperature, but can be dissolved by a few solvents above 212T, and can also be swollen by some solvents, especially chlorinated solvents. PCTFE has excellent gas barrier ability, and the water vapor permeability of its film products is the lowest among all transparent plastic films. Its electrical properties are similar to other perfluoropolymers, but the dielectric constant (2.3-2. Knife and dissipation factor is slightly higher, especially at high frequencies. PCTFE can make thick (1/8 inch) optically transparent parts.

Although PCTFE can be melt processed, it is difficult to process due to the high melt viscosity and the tendency to degrade, which leads to the deterioration of the properties of the processed products.

PCTFE resin can be made into pellets for molding and extrusion. Film thickness is 0.001-0.010 inches, and rods and tubes are also available. The PCTFE resins distributed in the US market include Kel-FI brand of 3M Company, Daiflon brand of Daikin Company, and Acfon brand of AlliedlSignal Company.

ethylene chlorotrifluoroethylene copolymer

ECTFE resin is a 1:1 alternating copolymer of ethylene and chlorotrifluoroethylene with a melting point of 464°F and a density of 1.68g/cc (grams per cubic centimeter).

This material has good performance from low temperature to 330T, and its strength, wear resistance and creep resistance are much higher than PTEE, FEP and PFA. It is resistant to most aggressive chemicals and organic solvents at room and elevated temperatures. It has a low dielectric constant (2.6) and is stable over a wide temperature and frequency range. ECTFE does not catch fire, prevents flame spread, and when exposed to flame, will decompose into hard carbon.

ECTFE can be made into pellets for molding and extrusion, and powdered products for rotational molding, fluidized bed coating, and electrostatic coating. It can be processed into foam products by chemical foaming method in traditional extrusion equipment, and it is not suitable for the field of computer wires. Semi-finished products are films, sheets, tubes and monofilaments. The ECTFE products sold by Ausimont USA are called Halar.

In the field of wires and cables, the most important applications are for booster cables, cables for public transport vehicles. Fire alarm cable, anode protection cable. Injection products include tower packing, interrogation and pump parts, connectors, wire terminals, and filter housings. The applications of ECTFE pipe include optical fiber casing, unsupported pipe, steel pipe and reinforced plastic pipe lining.

ECTFE coatings and Uchimura prevent metal from being eroded by the environment. Membrane applications are rational for battery and isolation applications. Applications of single fibers include oil mist eliminators, braided sleeves, and filter fabrics. Wide (48in) ECTFE sheet with glass fiber backing can be used as the lining of tanks with high chemical resistance and strength requirements.