Polyvinyl fluoride structure

The vinyl fluoride/vinylidene fluoride and the vinyl fluoride/tetra-fluoro ethylene copolymer systems were also studied (21). In the first case isomorphism is observed in the whole range of compositions, while the distribution of the two types of units is random. The crystal structure is that of polyvinyl fluoride, which is virtually identical with one of the three known crystalline forms of polyvinylidene fluoride, and characterized by a planar zig-zag chain conformation. High degrees of crystallinities in the whole range of compositions are also observed in the second case. However, the crystal structure of the two pure homopolymers is not the same hence we are in the presence of isodimorphism. In any case, for vinyl fluoride contents ranging between 0 and 75 mole-% the structure observed is essentially that of polytetrafluoro ethylene in the crystalline... 

More recently, the crystal structure of atactic polyvinyl fluoride, which is highly crystalline under ordinary conditions, was reported (49) here the atoms replacing each other randomly are hydrogen and fluorine, whose van der Waals radii are also similar ( 1.25 and 1.35 A respectively (48)). 

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. 

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. 

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... 

Polyvinyl halide n. A term sometimes used (almost exclusively in patents) for polymers and co-polymers of vinyl chloride. Aside from polyvinyl fluoride, which is more similar structurally to polyethylene, and brominated butyl rubber, which has enjoyed some use in the automobile-tire industry, no polymers containing the other halogens (bromine, iodine, and astatine) exist in commerce. 

Fabrics used as support are coated PVC, acryhc fabrics, glass fibre-based fabrics, thermoplastic olefin (TPO) fabrics, or structures coated by polyvinyl fluoride. 

PVDF belongs to the class of fluorinated ethylenes. With two fluorine atoms in the repeat unit, it contains 59.4% fluorine. The structure of the fluorinated ethylenes is shown in Figure 1. Of the four fluoroethylenes of this series, only polyvinyl fluoride (PVF), PVDF, and polytetrafluoroethyl-ene (PTFE) are commercially significant and only two i.e. PVDF and PTFE, found extensive applications as engineering plastics. 

This is a typical structure for many chain polymers, i.e. PE, PVC, PTFE, but can also occur with step polymerizations, e.g. polyethers (starting from cyclic ethers) and polysiloxanes (starting from R2SiCl2). Normally head-to-tail combination occurs in vinyl polymerization (Figure 1.1). Rarely does head-to-head interaction occur—exceptions include polyvinyl fluoride (PVF) and polyvinylidene difluoride (PVDF) where 20% head-to-head polymerization takes place, whereas with polypropylene (PP) < 0.5% occurs. 

Other plastics are used in plant structures, although less extensively. Among these are the acrylonitrile butadiene styrene (ABS) resins, the polyvinyl fluoride resins, the polycarbonate resins, and the polyurethanes. The epoxy resins have been used extensively in structural apph-cations (such as flooring) and adhesives. Specialized apphcations include use in chemically resistant coatings and in plasters for exposed aggregate wall finishes. 

For the unsymmetrical monomers polyvinyl fluoride, polyvinyl-idene fluoride and polytrifluoroethylene, the possibility arises of structural isomerism by way of head-to-tail and/or head-to-head addition. In fact, F studies show that structural isomerism does... 

Polyvinyl fluoride is a semicrystalline polymer and has a planar zigzag chain conformation. The extent of the polymer crystallinity is dependent on its polymerization method and thermal history. The degree of crystallinity can vary from 20-60%, apparently as a function of defects in the PVF structure. Studies have indicated the crystalline cell is orthorhombic and contains two monomer units. 

Although not strictly the subject matter of this book, work is briefly reviewed next on the application of non mass spectrometric Py-GC methods in the determination of polymer structure. This information is inclnded in the hope, when necessary, that chemists will be able to adapt these methods by including a mass spectrometric detailed information on polymer structure acrylates [63, 105-107], rubbers [63, 108-110], PVC [63,111-115], aliphatic polyhydrazides [116], polyoxamides [116], polyamides [117], polyether imides [118], methacrylamide [119], aromatic aliphatic polyamides [117], polyurethanes [120], chitin graft poly(2-methyl 2-oxazolone) [121, 122], polyxylyl sulfide [123-126], epoxy resins [127], polyethylene oxalate [128], polytetrafluoroethylene [129], polyvinylidene chloride [129], polyepichlorohydrin, fluorinated ethylene-propylene copolymer [129], polyvinyl fluoride [129], polyvinylidene [129], fluoride [129], SBR copolymer [129] and styrene-isoprene copolymer [130]. 

Polyvinyl fluoride (PVF) is a homopolymer of vinyl fluoride. The molecular structure of PVF is shown in Fig. 11.44. 

Mention has already been made of Redux 775, the first structural adhesive film. Its manufacturing process has not changed since 1954. A film of phenolic resole is cast under a doctor knife, a considerable excess of the Polyvinyl Fluoride (PVF) powder is curtain coated onto the phenolic film, and the excess is then... 

In addition to the general steric requirements reported in the introductory section for macromolecular isomorphism, if chains differ in chemical structure, they must also show some degree of compatibility to intimate mixing and not too much different crystallization kinetics. The first condition is strictly similar to the one that applies to liquid mixtures. As a well known example, liquids without reciprocal affinity in general cannot form a unique phase. Attempts to obtain mixed crystals from polyethylene and polyvinyl or polyvinylidene fluoride has been unsuccessful hitherto, in spite of the similarity in shape and size of their chains. In view of the above somewhat strict requirements, it is not surprising that relatively few examples of this type of isomorphism have been reported. 

Similarly, by melting together polyvinyl and polyvinylidene fluoride at all relative compositions a unique crystalline phase is observed, which is identical with the structure of crystalline polyvinylfluoride (49) and also with the structure of one of the crystalline forms of polyvinylidene fluoride (21). Since the lattice constants of these two forms are quite close, no variation is observed in the X-ray spacings of the solid mixtures throughout the whole range of compositions. The existence of a true co-crystallization is shown by the melting point/composition curve, which shows no minimum. 

The materials used in nonwoven fabrics include a single polyolefin, or a combination of polyolefins, such as polyethylene (PE), polypropylene (PP), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinylidine fluoride (PVdF), and polyvinyl chloride (PVC). Nonwoven fabrics have not been able to compete with microporous films in lithium-ion cells. This is primarily because of the inadequate pore-size structure and difficulty in making thin (<25 pm) nonwoven fabrics with acceptable physical properties. However, nonwoven separators have been used in button cells and bobbin cells when thicker separators and low discharge rates are acceptable. 

The NF membrane surface was further functionalized with 0.75% w/v Polyvinyl alcohol (PVA) solution to reduce the MWCO to 250 Da for better rejection of fluoride. Figures 4.9a and 4.9b represent the physical structures of RO polyamide and functionalized (FPA) 250 NF membranes. 

---