Polyvinylidene fluoride Fluoropolymers

Methyl chloroform serves as a raw material for the manufacture of polyvinylidene fluoride fluoropolymer. It also can be used as a raw material for the production of certain hydrochlorofluorocarbons having relatively short atmospheric residence... 

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. ... 

When enhanced temperature resistance is required, polyvinylidene fluoride or other fluoropolymers are used. Fluoropolymers have the advantage of being oil resistant and flame retardant, but are also more expensive base materials. PVDF is one of the materials that is very easy to cross-link by EB radiation. 

Fluoropolymers, such as copolymer of ethylene and tetrafluoroethylene (ETFE), 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.36... 

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). 

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. 

Fluoropolymer manufacturers and suppliers have developed time-temperature-shear-rate data for melt viscosity or melt flow rate (index) to provide an assessment of the thermal stability of these polymers. Figures 6.1 and 6.2 show the melt viscosity of a few commercial grades of polyvinylidene fluoride as a function of temperature at a fixed shear rate. The relationships between melt viscosity and shear rate, and shear stress versus shear rate, are presented in Figs. 

Fluoroplastic Homopolymer - A fluoropolymer entirely compiled of one monomer is called fluoroplastic homopolymer. Examples include poly-tetrafluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride. 

Polyvinylidene fluoride (PVDF) is a homopolymer of 1,1-difluoroethene with alternating CH2 and CF2 groups along the polymer chain. These groups impart a unique polarity that influences its solubility and electrical properties. The polymer has the characteristic stability of fluoropolymers when exposed to aggressive thermal, chemical, and ultraviolet conditions. 

Commonly used thermoplastics such as PE, polyvinyl chloride (PVC) and polypropylene (PP) are less costly than fluoropolymers, e.g. polyvinylidene fluoride (PVDF), but do not perform as weU in high temperature conditions. They also include plasticisers, heat stabilisers and fire retardants that can leach out. PVDF in its virgin form is highly pure and does not contain additives. 

There are numerous articles in the literature describing the synthesis and characterization of polymers with their main chains or side groups partially substituted by fluorine atoms. These low-fluorine polymers are usually soluble in common solvents and therefore are not included in this review. Only a few commercial fluoropolymers, which are soluble in uncommon solvents, are reviewed. These polymers include polyvinylidene fluoride, polyperfluoroethers, poly(bis-trifluoroethoxyphosphazenes), and polytrifluoroethylenes, and Kel-F polymer. 

When a flat solar collector is used, a polymer film based on fluoropolymers, e.g., Tedlar (S/ polyvinylidene fluoride, has been used to make a laminate with an adhesive. The solar collector, so formed, is light-weight and low-cost. 

Polyvinylidene fluoride n. (-H2CCF2-) . Thermoplastic fluorocarbon polymer derived from vinylidene fluoride. It is a fluoropolymer with alternating CFi2 and CF2 groups. PVDF is an opaque white resin. Extremely pure, it is superior for non-contaminating applications. In film form it is characterized by superior weather and UV resistance. Abbreviation is PVDF. 

Kawai s (7) pioneering work almost thirty years ago in the area of piezoelectric polymers has led to the development of strong piezoelectric activity in polyvinylidene fluoride (PVDF) and its copolymers with trifluoroethylene and tetrafluoroethylene. These semicrystalline fluoropolymers represent the state of the art in piezoelectric polymers. Research on the morphology (2-5), piezoelectric and pyroelectric properties (6-70), and applications of polyvinylidene fluoride 11-14) are widespread in the literature. More recently Scheinbeim et al. have demonstrated piezoelectric activity in a series of semicrystalline, odd numbered nylons (75-77). When examined relative to their glass transition tenq>erature, these nylons exhibit good piezoelectric properties (dai = 17 pCTN for Nylon 7) but have not been used commercially primarily due to the serious problem of moisture uptake. In order to render them piezoelectric, semicrystalline polymers must have a noncentrosynunetric crystalline phase. In the case of PVDF and nylon, these polar crystals cannot be grown from the melt. The polymer must be mechanically oriented to induce noncentrosynunetric crystals which are subsequently polarized by an electric field. In such systems the amorphous phase supports the crystalline orientation and polarization is stable up to the Curie temperature. 

Inappropriate matching of the physicochemical properties of the binder with the carbon material may influence dramatically upon the electroactive area via blocking of the SPE film or simply decreasing the electroactive surface area. Another point to be considered is the cost of the binders. For example, fluoropolymers such Nafion, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) are commonly used as binder in electrode preparation in the field of lithium-ion batteries or fuel cells. However, the curing process has to be soft in most cases... 

Polyvinyl chloride blends, see Polyvinyl chloride Polyvinylfluoride. see Fluoropolymers Polyvinylidene fluoride, see Fluoropolymers Post-crystallization 33 Post-processing 343 Post-stabilization 328 Primary radicals 332... 

There are two distinct families of fluoropolymers perfluorinated (like PTFE) and the partially fluori-nated (like PVDF) polymers. The major types that are rotationally molded are polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene (ETFE), ethyl-ene-chlorotrifluoroethylene (EC IFF), andperfluoro-alkoxy (PFA). 

Fluoropolymers, including polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PIPE), and perfluoroalkoxy (PFA)... 

Polyvinylidene fluoride (PVDF) is a thermoplashc fluoropolymer with a melt point of 352°F (178°C) and a wide usage range from -40°F ( 0°C) to 302°F... 

Fluoropolymers have outstanding chemical resistance, low coefficient of friction, low dielectric constant, high purity, and broad use temperatures. Most of these properties are enhanced with an increase in the fluorine content of the polymers. For example, polytetrafluoroethylene, which contains four fluorine atoms per repeat unit, has superior properties compared to polyvinylidene fluoride, which has two fluorine atoms for each repeat unit. Generally, these plastics are mechanically weaker than engineering polymers. Their relatively low values of tensile strength, deformation under load or creep, and wear rate require the use of fillers and special design strategies. 

There is a second class of fluoropolymers called partially fiuorinated in contrast to perfiuorinated polymers. These molecules include hydrogen (H) in addition to fluorine and carbon. Examples include polyvinyl fluoride, polyvinylidene fluoride, ethylene tet-rafluoroethylene copolymer, and ethylene-chlorotrifluo-roethylene copolymer. 

PVDF polymers are partially fluorinated and melt processible. They have a lower melting point and chemical resistance than perfiuorinated fluoropolymers. Polyvinylidene fluoride resins are, in general, homo-and co-polymers of vinylidene fluoride. PVDF resins are specified by ASTM Method D3222, which also provides procedures or references to other ASTM methods for the measurement of resin properties. Commercial PVDF resins offered by major manufacturers have been listed in Tables 6.10 through 6.14. 

Polyvinylidene fluoride is a semicrystalline fluoropolymer with at least three distinct crystaUine forms. The most common type is nonpolar and centrosym-metric, called the a phase, and forms when the polymer is cooled from its melt. Deformation of the atype crystallites such as stretching the extruded film at 80°C, results in packing of the unit cells in parallel planes into the polar P phase. The third crystallite is the y phase, which is intermediate between a and phases. Orientation of the /phase also generates phase crystallites. 

Fluoropolymer 9 Ammonium Hydrogen Carbonate Polyvinylidene Fluorides (PVDF) 6-9... 

Fluoropolymer, CTFE Polyvinylidene Fluorides (PVDF) Toluenesuifonyi Chioride ... 

---