Vinylidene fluoride polymers properties

Mascia, L., Pak, S.H., and Caporiccio, G. Properties Enhancement of Fluorosilicone Elastomers with Compatibilized Crystalline Vinylidene Fluoride Polymers, Eur. Polym. J. 31(5), 459 65, 1995. 

L. Mascia, S.H. Pak, G. Caporiccio, Properties enhancement of fluorosilicone elastomers with compatibilised crystalline vinylidene fluoride polymers, Eur. Pol. J. 31 (5) (1995) 459 65. 

Saito, et al.,[ prepared solutions of 0.1 g, 0.2 g, and 0.3 g of the vinylidene fluoride polymers in 50 ml of dimethylformamide (DMF) and measured the specific viscosity of these solutions at 30°C using a Ubbellohde viscometer. A plot of the ratio of specific viscosity to the corresponding solution concentration was made as a function of polymer concentration. The line of best fit to the data was extrapolated to zero concentration the intercept gave the value of the intrinsic viscosity for the polymer. Equation 5.13 could then be used to calculate the molecular weight of the polymer. A value of 300,000 was determined for the resin product of the copolymerization example previously described. This resin had excellent film forming properties as demonstrated by pressing 1 g of the poly-... 

The inability to process PTFE by conventional thermoplastics techniques has nevertheless led to an extensive search for a melt-processable polymer but with similar chemical, electrical, non-stick and low-friction properties. This has resulted in several useful materials being marketed, including tetrafluoro-ethylene-hexafluoropropylene copolymer, poly(vinylidene fluoride) (Figure 13.1(d)), and, most promisingly, the copolymer of tetrafluoroethylene and perfluoropropyl vinyl ether. Other fluorine-containing plastics include poly(vinyl fluoride) and polymers and copolymers based on CTFE. 

A 50 50 mol/mol copolymer of hexafluoroisobutylene (CH2 = C(CF3)2) and vinylidene fluoride was made available by Allied Chemical in the mid-1970s as CM-1 Fluoropolymer. The polymer has the same crystalline melting point as PTFE (327°C) but a mueh lower density (1.88g/cm ). It has excellent chemical resistance, electrical insulation properties and non-stiek characteristics and, unlike PTFE, may be injeetion moulded (at 380°C). It is less tough than PTFE. 

Hietala, S., Skou, E. and Sundhokn, F. 1999. Gas permeation properties of radiation-grafted and sulfonated poly-(vinylidene fluoride) membranes. Polymer 40 5567-5573. 

Examples of fluoroplastics include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), ethylene—chlorotrifluoroethylene (ECTFE), ethylene—tetrafluoroethylene (ETFE), poly(vinylidene fluoride) (PVDF), etc (see Fluorine compounds, organic). These polymers have outstanding electrical properties, such as low power loss and dielectric constant, coupled with very good flame resistance and low smoke emission during fire. Therefore, in spite of their relatively high price, they are used extensively in telecommunication wires, especially for production of plenum cables. Plenum areas provide a convenient, economical way to run electrical wires and cables and to interconnect them throughout nonresidential buildings (14). Development of special flame-retardant low smoke compounds, some based on PVC, have provided lower cost competition to the fluoroplastics for indoors application such as plenum cable, Riser Cables, etc. 

Poly(vinylidene fluoride) with the sequence (CF2-CH2)n is a well known ferroelectric polymer in the crystalline state where the chains adopt an all-trans conformation [424]. This structure could provide interesting properties if used as building block of LC. 

The preceding structural characteristics dictate the state of polymer (rubbery vs. glassy vs. semicrystalline) which will strongly affect mechanical strength, thermal stability, chemical resistance and transport properties [6]. In most polymeric membranes, the polymer is in an amorphous state. However, some polymers, especially those with flexible chains of regular chemical structure (e.g., polyethylene/PE/, polypropylene/PP/or poly(vinylidene fluoride)/PVDF/), tend to form crystalline... 

Chlorotrifluoroethylene monomer serves as a building block for the CTFE telomer oils as well as the solid higher polymer and various copolymers. CFC-113 also may be used in the production of trifluoroethylene monomer by vapor-phase reduction using hydrogen and a precious metal catalyst, usually palladium [reaction (9)]. Copolymers of trifluoroethylene and vinylidene fluoride show interesting piezoelectric properties. 

Of greater interest in recent years have been the peculiar piezolectric properties of poly(vinylidene fluoride). In 1969 it was observed" that stretched film of the polymer heated to 90°C and subsequently cooled to room temperature in a direct current electric field was 3-5 times more piezoelectric than crystalline quartz. It was observed that the piezolectric strain coefficients were higher in the drawn film and in the normal directions than in the direction transverse to the film drawing. 

Blends of poly(3-hydroxyalkanoic acid)s (PHAs) with various natural and synthetic polymers have been reported as reviewed in Refs. [21,22]. By blending with synthetic polymers it is expected to control the biodegradability, to improve several properties, and to reduce the production cost of bacterially synthesized PHAs. The polymers investigated as the blending partners of PHAs include poly(ethylene oxide) [92, 93], poly(vinyl acetate) [94], poly(vinylidene fluoride) [95], ethylene propylene rubber [94, 96], po-ly(epichlorohydrin) [97, 98], poly(e-caprolactone) [99], aliphatic copolyesters of adipic acid/ethylene glycole/lactic acid [100] and of e-caprolactone/lactide... 

---