Fluorinated ethylene propylene plastic

Fluorinated polymers stand out sharply against other construction materials for their excellent corrosion resistance and high-temperature stability. In this respect they are not only superior to other plastics but also to platinum, gold, glass, enamel and special alloys. The fluorinated plastics used in process plants are polytetrafluorethylene (PTFE), fluorinated ethylene/ propylene (FEP), polytrifiuoromonochlorethylene (PTFCE) and polyvinyl fluoride (PVF). They are much more expensive than other polymers and so are only economical in special situations [59]. 

Polytetrafluoroethylene and fluorinated ethylene-propylene are the only resins composed wholly of fluorine and carbon. The polymer consists of fluorine atoms surrounding the carbon chain as a sheath, giving a chemically inert and relatively dense product from the strong carbon-fluorine bonds. Polytetrafluoroethylene must be molded at high pressure. Fluorinated ethylene-propylene c.m be injection molded and extruded as thin fdm. Both plastics have exceptional heat resistance... 

Fluorinated ethylene propylene (Teflon) (FEP) is a fully fluori-nated plastic. This polymer was developed to have a combination of unique properties. It combines the desirable properties of PTFE with advantageous melt processing properties. 

It resembles polytetrafluoroethylene and fluorinated ethylene propylene in its chemical resistance, electrical properties, and coefficient of friction. Its strength, hardness, and wear resistance are about equal to the former plastic and superior to that of the latter at temperatures above 150°C. 

Radioisotope detection of P, 14C, and Tc was reported by Kaniansky et al. (7,8) for isotachophoresis. In their work, isotachophoretic separations were performed using fluorinated ethylene-propylene copolymer capillary tubing (300 pm internal diameter) and either a Geiger-Mueller tube or a plastic scintillator/photomultiplier tube combination to detect emitted fi particles. One of their reported detection schemes involved passing the radiolabeled sample components directly through a plastic scintillator. Detector efficiency for 14C-labeled molecules was reported to be 13-15%, and a minimum detection limit of 0.44 nCi was reported for a 212 nL cell volume. 

The family of FPs, also called fluorocarbon plastics, is based on polymers made of monomers composed of fluorine and carbon may also include chlorine atoms in their structure. Specific types include polytetrafluoroethylene (PTFE), polytetrafluoroethylene-cohexafluoro-propylene or fluorinated ethylene propylene (FEP), polytrafluoroethylene-coperfluoropropylvinyl ether (PFA), ethylenetetrafluoroethylene (ETFE). polychlorotrifluoroethylene (PCTFE), ethylene-chlorotri-fluoroethylene (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoromethylvinylether (PFMV), perfluoroalkoxy (PFA), etc. 

FIGURE 5.4 Permeability measurements for hydrogen and oxygen diffnsion through different plastic materials. FEP, fluorinated ethylene propylene PFA, perfinoroalkoxy fluorocarbon ETFE, ethylene-tetrafluoroethylene. 

Storage of water samples to detect trace metals is normally carried out in plastic containers fluorinated plastic materials i.e.. Teflon, fluorinated ethylene propylene (FEP), perfluoroalkoxy polymers (PFA) or polyethylene are used because if opportunely treated and conditioned they guarantee contamination-free samples. However, FEP or Teflon bottles are preferable to those made of polyethylene when speciation studies are carried out. In fact, polyethylene over long periods of storage can release plasticizers (above all phthalates or amines), which behave as ligands and modify the complexation equilibria of the solution. When Hg is to be determined plastic materials must be avoided because they are permeable to gases and vapours glass or quartz are therefore used. 

Fluorinated ethylene propylene has a crystalline melting point of 290 C and a specific gravity of 2.15. It is a relatively soft plastic with lower tensile strength, wear resistance, and creep resistance than many other engineering plastics [186]. 

Both on-column and post-column detection schemes have been developed for radionuclide detection for CE. The most common type used is an on-column configuration, which yields detection limits in the 10 M range for isotopes such as P. Isotachophoretic separations of C were among the first examples of online capillary radionuclide detection, performed by Kaniansky et al. The associated instmment uses 300-p,m ID fluorinated ethylene-propylene copolymer capillary tubing, and the separation eluent flows directly into a plastic scintillator cell between two PMTs. The scintillation events are detected coincidentally between the two PMTs, such that only if both PMTs receive an input within a short time will they register the count as signal. This kind of coincidence detection ensures that nonscintillation photons that come from outside the detection cell and only hit one PMT are not counted. This system exhibits a detection limit of 16 Bq for analytes, with a detector efficiency of 13-15%. 

All TP or TS matrix property can be improved or changed to meet varying requirements by using reinforcements. Typical thermoplastics used include TP polyesters, polyethylenes (PEs), nylons (polyamides/ PAs), polycarbonates (PCs), TP polyurethanes (PURs), acrylics (PMMAs), acetals (polyoxymethylenes/POMs), polypropylenes (PPs), acrylonitrile butadienes (ABSs), and fluorinated ethylene propylenes (FEPs). The thermoset plastics include TS polyesters (unsaturated polyesters), epoxies (EPs), TS polyurethanes (PURs), diallyl phthalates (DAPs), phenolics (phenol formaldehydes/PFs), silicones (Sis), and melamine formaldehydes (MFs). RTSs predominate for the high performance applications with RTFs fabricating more products. The RTPs continue to expand in the electronic, automotive, aircraft, underground pipe, appliance, camera, and many other products. 

It is important in some applications that the polymer does not embrittle outside a certain temperature range. Engineering plastics, which do not embrittle include LDPE, HDPE, PA, PTFE, ethylene-trifluoroethylene copolymer, fluorinated ethylene-propylene copolymer and silicones. PP, epoxy resins and polymethyl pentene are all subject to embrittlement. 

For practical purposes there are eight types of fluoropolymers, as summarized in Table F.7. Included in this family of plastics are polytetrafluoroethylene (FIFE), polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF), fluorinated ethylene propylene (FEP), and others. Depending on which of the fluoropolymers are used, they can be produced as molding materials, extrusion materials, dispersion, film, or tape. Processing of fluoropolymers requires adequate ventilation for the toxic gases (HF) that may be produced. 

Figure 6-61. Heat-resistance properties of resins retaining 50 percent of properties obtainable at room temperature with resin exposure and testing at elevated temperature. Zone 1 Acrylics, cellulose esters, LDPE, PS, PVC, SAN, SBR, UF, etc. Zone 2 Acetals, ABS, chlorinated polyether, ethyl cellulose, EVA, ionomer, PA, PC, HDPE, PET, PP, PVC, PUR, etc. Zone 3 PCTFE, PVDF, etc. Zone 4 Alkyds, fluorinated ethylene-propylene, MF, polysulfone, etc. Zone 5 TS acrylic, DAP, epoxy, PF, TS polyester, PTFE, etc. Zone 6 Parylene, polybenzimidazole, silicone, etc. Zone 7 PAI, PI, etc. Zone 8 Plastics in R D etc. Since plastics compounding is rather extensive, certain basic resins can be modified to meet different heat-resistance properties.

Electrical applications -FEP m [FLUORINE COMPOUNDS, ORGANIC - PERFLUORINATED ETHYLENE-PROPYLENE COPOLYMERS] (Vol 11) -ofplastic foams [FOAMED PLASTICS] (Vol 11)... 

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