Extrusion polyvinyl fluoride dispersion

Both twin- and single-screw extruders can be applied in the extrusion of polyvinyl fluoride dispersion. A gel (viscosity of200-400 poise at 170°C) is formed in the extruder as a result of heating the dispersion. The solvent must have the appropriate volatility to permit the coalescence of the resin into a continuous coating/film before it has completely evaporated from the gel. 

Polyvinyl fluoride (PVF) -CHF-CH2- 190 - - Melt extrusion of dispersion in latent solvent... 

For practical purposes there are eight types of fluoropolymers, as summarized in Table F.7. Included in this family of plastics are polytetrafluoroethylene (FIFE), polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF), fluorinated ethylene propylene (FEP), and others. Depending on which of the fluoropolymers are used, they can be produced as molding materials, extrusion materials, dispersion, film, or tape. Processing of fluoropolymers requires adequate ventilation for the toxic gases (HF) that may be produced. 

In this chapter, preparation and characterization of copolymers of tetrafluoroethylene, copolymers of chlorotrifluoroethylene (CTFE), homopolymers and copolymers ofvinylidene fluoride (VDF), and homopolymers and copolymers of vinyl fluoride (VF) are described. All of these polymers, except for polyvinyl fluoride (PVF), are processed by melt techniques. PVF is processed by the extrusion of a dispersion of the polymer in a polar latent solvent. 

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See also in sourсe #XX -- [ ]

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