Fluoropolymers PCTFE

Many vinyl monomers were reported to have been grafted onto fluoropolymers, such as (meth)acrylic acid and (meth)acrylates, acrylamide, acrylonitryl, styrene, 4-vinyl pyridine, N-vinyl pyrrolidone, and vinyl acetate. Many fluoropolymers have been used as supports, such as PTFE, copolymers of TFE with HFP, PFAVE, VDF and ethylene, PCTFE, PVDF, polyvinyl fluoride, copolymers ofVDF with HFP, vinyl fluoride and chlorotrifluoroethylene (CTFE). The source of irradiation has been primarily y-rays and electron beams. The grafting can be carried out under either direct irradiation or through the use of preliminary irradiated fluoropolymers. Ordinary radical inhibitors can be added to the reaction mixture to avoid homopolymerization of functional monomers. 

The fluoropolymer family consists of polymers produced from alkenes in which one or more hydrogens have been replaced by fluorine. The most important members of this family are polytetrafluoroethylene (PTFE) (XLVII), polychlorotrifluoroethylene (PCTFE) (XLVIII), poly(vinyl fluoride) (PVF) (XLIX), poly(vinylidene fluoride) (PVDF) (L) copolymers of... 

PCTFE is highly suitable for applications at extremely low temperatures however, at elevated temperatures it is inferior to other fluoropolymers with the exception of... 

PCTFE. Very little work was done on the effects of radiation on PCTFE but it is known that its resistance to radiation is superior to that of other fluoropolymers.34... 

Very little work has been reported on the effects of irradiation of PCTFE. One source claims that the resistance of PCTFE to ionizing radiation is superior to that of other fluoropolymers [42], Another work reports that poly(chlorotrifluoroethylene) degrades when exposed to ionizing radiation in a similar fashion as PTFE at ambient... 

Fluoropolymers discussed include polytetrafluoro-ethylene (PTFE), perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene polymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). 

Aside from PTFE and PCTFE, copolymers of TFE and a few other fluorocarbon polyuners are processed by melt-processing methods. Commercial fluoropolymers that have found application in chemical processing industries include PFA, FEP, ETFE, ECTFE, and PVDF. These plastics are fabricated into parts by common techniques such as injection molding, transfer molding, blow molding, compression molding, rotational molding, and extrusion (Table... 

Known in Germany since 1933, polytetrafluoro-ethylene (PTEE) is a semicrystalline resin (92-98% crystallinity), with T = 342°C and melt viscosity of 7 - 10 GPas. Others, more common fluoro-polymers are polychlorotrifluoroethylene (PCTFE), Hostaflon commercialized in 1934, fluorinated ethylene-propylene (FEP), Teflon -FEP introduced in 1972, and numerous copolymers with Tjjj = 260 to 304°C, processable at = 315 to 425°C, and having the degradation temperature, deg 440°C. The fluoropolymers are... 

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. 

PTFE, PCTFE, and all other fluoropolymers (Eigure 21.1) gained immediate acceptance during commercialization in the various markets. During the ensuing decades, many fluoropolymers, including fluorothermoplastics and fluoroelastomers, were developed. The entire sales volume for fluoropolymers is today more than 230,000 tons per year (world consumption for fluoroplastics in 2012 216,000 tons [4] world consumption for fluoroelastomers in 2009 20,000 tons [5]). The total market value is more than US 4 billion. 

Poly(chlorotrifluoroethylene) (PCTFE, Kel-F fluoropolymer) is a thermoplastic semicrystalline polymer with (-CF2CCIF-) repeating units [49], Typically, PCTFE is synthesized via a free radical polymerization using bulk, suspension, or emulsion techniques [50]. Compared with PTFE (Teflon fluoropolymer), which has similar chemical properties, there is asymmetry in the CTFE monomer unit due to the presence of the chlorine atom in CFCl groups. Consequently, the NMR features of PCTFE are more complicated due to the possible monomer- and stereo-sequence variations. Since PCTFE has various distinguished properties, including thermal, chemical, and radiation resistance, low vapor permeability, and electrical insulation [51,52], it has... 

Apart from the influence of chemical and physical modifiers, particle size, surface area and morphology not only play an important role in the rate of reaction of any fuel oxidizer mix but also interfere with combustion efficiency and thus radiant energy release. Figure 10.29 shows the particle size distribution of four different fluoropolymers, including PCTFE. The influence of different origin and particle size distributions of PTFE on radiant intensity is depicted in Figures 10.30 and 10.31. 

Figure 3.1 Evolution of fluoropolymer development over time. PCTFE, Polychlorotrifluoroethylene PVDF, poly-vinylidene fluoride PVF, polyvinyl fluoride FEP, fluorinated ethylene propylene copolymer ECTFE, ethylene-chlorotrifluoroethylene copolymer ETFE, ethylene-tetrafluoroethylene copolymer PFA, perfluoroalkoxy copolymer AF, amorphous fluoropolymer.

Another inventionl l has described a method of producing a laminated composite for use as intravascular catheters such as angioplasty catheters (Fig. 10.48). In the first step, a parison was formed in a coextrusion of multilayer sheet through a die. The parison was heated in a mold and drawn to several times of original length. Next, the parison was expanded radially to the desired dimension and strength. The exterior of the expander was coated with hydrophilic material. Finally, the expander was bonded to the exterior of a tubular catheter. Fluoropolymers such as ETFE, ECTFE, PCTFE, PVDF, and PEA have been mentioned as intermediate layers that bond the outer layer (polyethylene terphthalate, PET), which were coextruded. 

Perfluoropolymers bum, but do not continue to bum when the flame is removed. All perfluorinated fluoropolymers pass a UL 83 vertical flame test and are classified 94 V-0 according to Underwriters Laboratory (UL) in their burning test classification for polymeric materials. Limiting oxygen index (LOI) by ASTM D2863 is 95% or higher for PTFE, PFA, FEP, and PCTFE. Partially fluorinated fluoropolymers are more flame resistant than other thermoplastics but not quite as resistant as the perfluorinated fluoropolymers, as evidenced by their lower EOI values. PVDF, ETFE, and ECTFE meet UE 94 V-0. Table 13.48 lists the EOI of various fluoropolymers. 

It is necessary to modify the surface of fluoropolymers to obtain stronger adhesive bonds. Modification or surface treatment alters the structure of the polymer at the surface enabling formation of true adhesive bonds. Mechanical abrasion imparts little improvement and chemical etching is required. Chemical resistance of perhalogenated polymers such as PTFE, PFA, FEP, and PCTFE mandates the use of highly potent agents. 

The addition of one chlorine atom contributes to lowering of the melt viscosity to permit extrusion and injection molding. It also contributes to the transparency, the exceptional flow, and the rigidity characteristics of the polymer. Fluorine is responsible for its chemical inertness and zero moisture absorption. Therefore, PCTFE has unique properties. Its resistance to cold flow, dimensional stability, rigidity, low gas permeability, and low moisture absorption are superior to those of any other fluoropolymer. It can... 

A number of fluoropolymers have been activated by various techniques [112,113— 120] thermal, corona, ozone, swift heavy ions, plasma, electron beam, or X-rays. Indeed, ozone smoothly activates fluoropolymers, in contrast to electron beam or X-ray radiation, which irradiate aU the bulk and produce peroxides in high amount. This section deals with the synthesis of fluorinated graft copolymers by the grafting from method that is, the fluorinated polymers have been first activated by ozoniza-tion or various other means (plasma, thermal, y-rays, or electrons) (first part), followed by a subsequent reaction of grafting (second part). In each part, the fluorinated comb-like copolymers can be prepared from different F-homopolymers (e.g., PTFE, PVDF, and PCTFE), and also from those arising from the different families of F-copolymers, such as FEP, ETFE, and poly(TFE-co-PAVE) (PFA). 

This resin is a fluoropolymer with excellent chemical resistance.See Chapter 6 for more information about the treatment methods for PCTFE. 

The commercially important fluorocarbon polymers are poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly[tetrafluoroethylene-co-(perfluoroaJkylvinyl ether)] (PFA), and amorphous fluoropolymer (AF), typically copolymers of tetrafluoro-ethylene and fluorinated dioxole. The second group of fluoropolymers includes modified poly(tetrafluoroethylene-co-ethylene) (ETFE), poly(vinylidene fluoride) (PVDF) (sometimes referred to as PVF2), and copolymers of vinylidene fluoride, poly(chlorotrifluoroethylene) (PCTFE), poly(chlorotrifluorethylene-co-ethylene) (E/CTFE) and poly(vinyl fluoride) PVF. 

Poly(chlorotrifluoroethylene) (PCTFE) was the first of the fluoropolymers to be made (Ref. 3). It was not imtil the watk of W. T. Miller and his eolle ues during flie research for the Manhattan (atom bomb) project (Ref. 8), however. 

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