Polymers polyvinyl fluoride

The principal materials used for pyroelectric detectors are members of the TGS group, lithium tantalate, strontium barium niobate, ceramics members of the lead zirconate titanate (PZT) group and, more recently, films of the polymers polyvinyl fluoride (PVF) and polyvinylidene fluoride (PVFj). 

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]. 

Polyvinyl Fluoride. See Vinylfluoride Polymer in this Section... 

Polyvinyl fluoride and PVDF are more stable to elevated temperatures than the corresponding chloride polymers. The decomposition temperatures of polytrifluoroethylene and polytetrafluoroethylene (ptfe) are progressively higher than polymers of vinyl fluoride or vinylidene fluoride. The pyrolysis of PAN and polymethacrylonitrile yields polycyclic ladder polymers. 

PVC, another widely used polymer for wire and cable insulation, crosslinks under irradiation in an inert atmosphere. When irradiated in air, scission predominates.To make cross-linking dominant, multifunctional monomers, such as trifunctional acrylates and methacrylates, must be added. Fluoropolymers, such as copol5miers of ethylene and tetrafluoroethylene (ETFE), or polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack, and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance. Ethylene propylene rubber (EPR) has also been used for wire and cable insulation. When blended with thermoplastic polyefins, such as low density polyethylene (LDPE), its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation. ... 

PVDF is among the few semicrystalline polymers that exhibit thermodynamic compatibility with other polymers,80 in particular with acrylic or methacrylic resins.81 The morphology, properties, and performance of these blends depend on the structure and composition of the additive polymer, as well as on the particular PVDF resin. These aspects have been studied and are reported in some detail in Reference 82. For example, polyethyl acrylate is miscible with polyvinylidene fluoride, but polyisopropyl acrylate and homologues are not. Strong dipolar interactions are important to achieve miscibility with PVDF, as suggested by the observation that polyvinyl fluoride is incompatible with polyvinylidene fluoride.83... 

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. 

Many of the PFCs discussed above, especially FSAs and FTOHs, are often building blocks used in the creation of fluorinated polymers. Fluorinated polymers are characterized by a hydrocarbon backbone, from which PFCs are appended, typically using ester, ether, urethane or methacrylate linkages [6, 7]. It is important to note that fluorinated polymers are not the same materials as fluoropolymers (such as polytetrafluoroethylene and polyvinyl fluoride) which are typically characterized by a fluorocarbon backbone [7]. 

Polyvinylidene fluoride (PVDF) is considerably less thermally stable than PTFE but much more stable than polyvinyl fluoride (PVF) or polychlorotrifluoroethylene (PCTFE). Certain inorganic compounds (silica, titanium dioxide, and antimony oxide) can catalyze its decomposition at temperatures above 375°C (707°F) [10], ETFE degradation is autocatalytic and similar to that of PVDF and is accompanied by the evolution of hydrogen fluoride (HF). Iron and transition metal salts can accelerate the degradation of ETFE by dehydrofluorination and oligomer formation [10], Copper salts have been found to stabilize the polymer [11], ETFE decomposes rapidly at temperatures above 380°C (716°F) [11],... 

Chain-stripping the reactive substituents or side groups on the polymer chain are eliminated, leaving an unsaturated chain. This polyene then undergoes further reaction, including (3-scission, aromatization and coke formation. (Polyvinylchloride, polyvinyl fluoride, polyacrylonitrile)... 

Tedlar is a tradename, property of the E.l. duPont Company for a polyvinyl fluoride polymer which is manufactured by casting in a sheet and stretching to orient the molecules. The personnel of the Elastomers Division of that company advise that Tedlar has excellent resistance to most inorganic acids, bases and salts, and to many, but by no means all, organic compounds and solvents, especially in the liquid phase. However, some solvents in the vapor phase can slowly diffuse through it. The Sauereisen Cement Co., of Pittsburgh, PA, supplies this sheet under the tradename of Sauereisen 90. 

Polytetrafluoroethylene (PTFE Teflon) was discovered accidently by PlunkettCZ nd commercialized by DuPont in the 1940 s. This polymer has a solubility parameter of about 6H and a high melting point of 327°C and is not readily moldable. Poly-chlorotrifluoroethylene (CTFE, Kel-F), the copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), polyvinylidene fluoride (PVDF, Kynar), the copolymer of tetrafluoroethylene and ethylene (ETFE), the copolymer of vinylidene fluoride and hexafluoroisobutylene (CM-1), perfluoroalkoxyethylene (PFA) and polyvinyl fluoride (PVF, Tedlar) are all more readily processed than PTFE. However, the lubricity and chemical resistance of these fluoropolymers is less than that of PTFE. 

Polymer stability varies greatly. Polymethyl methacrylate, bisphenol polycarbonate, and polyvinyl fluoride last for many years of outdoor exposure. The first two can be used for unbreakable windows in buses, schools, and elsewhere. The problem is that they become scratched. A... 

There is a second class of fluoropolymers called partially fluorinated in contrast to perfluorinated polymers. These molecules include hydrogen (H) in addition to fluorine and carbon. Examples include polyvinyl fluoride, pol5winylidene fluoride, ethylene tetrafluoroethylene copolymer, and ethylene chlorot-rifluoroethylene copol mier. 

There are a number of other polymers in this family including polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF), polyvinylidene fluoride, ethylene chlorotrifluoroethylene (ECTFE), tetrafluoroethylene/hexafluoropropylene/vi-nylidene fluoride terpolymers, and chlorotrifluo-roethylene/vinyl ether copolymers. 

Maximum oxygen uptake decreases with an increase in the fluorine content of the polymers. For example, pol5winylidene fluoride took up less oxygen as a result of O3 exposure than polyethylene, though more than PTFE, in the same experiment. The exception to this trend is polyvinyl fluoride, which has a higher etch rate than polyethylene (Table... 

Partially fluorinated fluoropolymers with commercial significance include ethylene-tetrafluoro-ethylene copolymer (ETFE), ethylene-chlorotrifluo-roethylene copolymer (ECTFE), pol wnylidene fluoride (PVDF), and polyvinyl fluoride (PVF). The presence of hydrogen in these plastics lowers the fluorine content compared to perfluoropol5miers, and renders them susceptible to some chemicals. This means that care must be taken in the selection of these polymers to insure compatibility of process fluids. 

Fluoropolymers are chemically stable and inert or relatively unreactive. Reactivity, generally, decreases as the fluorine content of the polymer increases. Fluorine induces more stability than chlorine. The fluoropolymer family of plastics has low toxicity and almost no toxicological activity. No fluoropolymers have been known to cause skin sensitivity and irritation in humans. Polyvinyl fluoride contains one fluorine atom and three hydrogen atoms per monomer unit and has been shown to cause no skin reaction in human beings.Excessive human exposure to fluoropolymer resin dust resulted in no toxic effects, although urinary fluoride content increased. 

This volume continues in the same format as the first edition with updates on the syntheses of various types of polymers, including olefin-sulfur dioxide copolymers, polythioesters, sulfide polymers, polyisocyanates, polyoxyalkyihydroxy compounds, polyvinyl carbazole, polyvinyl acetate, polyallyl esters, polyvinyl fluoride, and miscellaneous polymer preparations. The book should be useful to academic and industrial chemists who desire typical synthetic procedures for preparing the polymers described herein. In addition to reviewing the latest journals, we survey the patent literature and give numerous additional references. 

Polyvinyl Fluoride Crystalline thermoplastic polymer of vinyl fluoride has good toughness, flexibility, weatherability, and low-temperature and abrasion resistance. Processed by film techniques. Used in packaging, glazing, and electrical devices. Also called PVR... 

The preceding discussion has to do with induced dipoles whereas, the relaxation studies deal with the motions of parts of polymer chains that have different relaxation times for orientation. Many polymers such as polyvinyl fluoride, polyvinyl chloride and nylons have permanent dipoles that may be reoriented on the application of an applied field. The response of the oriented permanent dipoles will vary with the strength of the applied field. 

The addition of gel-forming components (plasticizers) to polymer electrolytes (see the above) produces gel like structures. Therefore, this type of ion-conducting polymers can also be described as gel polymer electrolytes. Gel polymer electrolytes can also be prepared, if a solution of a salt in an organic solvent is added to a polymer matrix (polyvinyl chloride, polyvinyl fluoride). The solvent dissolves in the polymer matrix and forms a gel like structure. The conductivity as well as the current density and rate of diffusion, etc., are determined by the mobUity of the solvated ions in the polymer matrix. The transport constants are again proportional to the free volume in the polymer. 

Unlike polytetrafluoroethylene, polyvinyl fluoride, poly(vinylidine fluoride), and polytrifluor-oethylene yield primarily on heating HF [457]. Among these three, poly(vinylidine fluoride) yields larger amounts of HF than do the other two polymers with an accompanying formation of double bonds. 

S Polyvinyl fluoride (PVF). Polyvinyl fluoride (PVF) is a crystalline polymer available in film form and used as a lamination on plywood and other panels. The film is impermeable to many gases. PVF is structurally similar to polyvinyl chloride (PVC) except for the replacement of a chlorine atom with a fluorine atom. PVF exhibits low moisture absorption, good weatherability, and good thermal stability. Similar to PVC, PVF... 

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