Applications for PVDF

FIGURE 4.20 Parts from PVDF. (Courtesy of Solvay Solexis.) 

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The most important fields of application for PVDF resias iaclude electric and electronic iadustry products, architectural and specialty finishes, products for the chemical and related iadustries, and rapidly growing specialized uses. 

The polymer, like many fluorine-containing polymers has very good weathering resistance and may also be used continuously up to 150°C. Outside of the electrical field it finds use in fluid handling, in hot water piping systems, in packaging and in chemical plant. A widely used specific application for PVDF is in ultra-pure water systems for the semiconductor industry. 

All the common extrusion techniques can be used to process PVDF into various products, such as rod, sheet, film, pipe, tubing, monofilament, wire insulation, etc.f No extrusion additives, lubricants, or heat stabilizers are needed. Equipment with materials of construction similar to those used for extruding PVC and polyolefins is applicable for PVDF. Extrusion temperatures vary from 210°C to 270°C depending on the type of PVDF resin and the shape being extruded. Extruders with L/D ratios of at least 20 are recommended. For very thin products, the temperature at the dietip can be as high as 320° C as required for heat polishing. 

PVDF is used in many diverse industrial applications for products that require high mechanical strength and resistance to severe environmental stresses. 

While several niche applications for OD have been identified, the commercial acceptance of the technology has been hampered by the nonavailability of a suitable membrane-membrane module combination. Fluoropolymer membranes, such as PTFE and PVDF, have been shown to provide superior flux performance, but are still unavailable in hollow fiber form with a suitable thickness for use in OD applications. The inherently low flux of OD requires fhaf membranepacking density be maximized for effective operation, and hence the available flat-sheet form of perfluoro-carbon membranes is unsuitable for commercial use. Four-port hollow fiber modules that provide excellent fluid dynamics are currently available, but only low-flux polypropylene membranes are utilized. 

The investigation of orientational effects arising from drawing is one of the main applications for NMR wideline measurements of PVDF. Thus, Clements et al. [50] used a two-component model for the deconvolution of... 

Polymeric membranes are prepared from a variety of materials using several different production techniques. Table 5 summarizes a partial list of the various polymer materials used in the manufacture of cross-flow filters for both MF and UF applications. For microfiltration applications, typically symmetric membranes are used. Examples include polyethylene, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) membrane. These can be produced by stretching, molding and sintering finegrained and partially crystalline polymers. Polyester and polycarbonate membranes are made using irradiation and etching processes and polymers such as polypropylene, polyamide, cellulose acetate and polysulfone membranes are produced by the phase inversion process.f Jf f ... 

There are various operation modes for piezoelectric sensors, depending on the crystallographic orientation of the plate and the material [1]. These modes include transversal compression, thickness or longitudinal compression, thickness shear action and face shear action. Also available are piezoelectric polymeric films, which are very thin, lightweight and pliant, such as polyvinylidene fluoride (PVDF) [3,4]. These films can be cut easily and adapted to uneven surfaces. Resonance applications are not possible with PVDFs because of their low mechanical quality factor. However, they can be used in acoustical broad-band applications for microphones and loudspeakers. 

In another example, ] a coolant conduit is described that consists of multiple polymer layers that render the composite stmcture resistant to hydrolysis and pressure with high burst strength. Motor vehicle engines are an application for a tubular form of this conduit (Fig. 6.61). In a two-layer construction, the inner layer was comprised of a fluoropol5mier such as ETFE, FEP, or PVDF that has been functionalized for compatibility with the polyamide outer layer. Such a tube was formed by blow molding. 

A large number of apphcations have been proposed for piezoelectric polymers. The types of applications can be grouped into live major categories sonar hydrophones, ultrasonic transducers, audio-frequency transducers, pyroelectric sensors, and electromechanical devices. The principal polymers of interest in these applications are PVDF and copolymers of vinylidene fluoride and trifluoroethylene. 

Table 4. Applications Profile for PVDF Homopolymers and Copolymers in Key Markets... 

Japanese application almost exclusively. Nylon monofilaments blended with PVDF have high knot strength and improved surface smoothness (98). Blends with polyethylene fibers (99) Developing market for PVDF in competition with established fluoroelastomer products... 

Because of KYNAR PVDF s excellent balance of properties, numerous applications for the resin soon developed. The markets for PVDF resins include ... 

Electric properties are an essential asset of fluoropolymers, in particular for PVDF. With the recent technological boom of touchpad, this polymer found additional applications in electronic haptic technology. 

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