Fluoropolymers melt-processible films

Melt-processible fluoropolymers can be directly welded while PTFE requires an adhesive ring. PFA film (13-50 pm thick) is the most effective adhesive material for welding PTFE. A PFA ring is inserted on each end of the tube and the ends are brought into contact be means of the welding device (Fig. 

Uses Melt-processable fluoropolymer for extrusion (wire coating, tubing, film), inj. molding, blow molding, compr. molding, rotomolding, electrostatic coating, industrial... 

The polymer in this sulfonyl fluoride form is thermoplastic and can be melt processed with conventional fluoropolymer processing equipment. For use in chlor-alkali electrolyzers, the polymer is extruded to film form and reinforced, if necessary, with... 

The serendipitous discovery of polytetrafluoroethylene (PTFE) in 1938 by Roy J. Plunkett [82] and his co-workers at DuPont research laboratories has spurred the development of a variety of fluorine containing polymers, which include fluorosilicones, fluorinated polyurethanes, fluorinated thermoplastic elastomers, etc.. Many of the commercial fluoropolymers are suitable for melt processing via conventional injection molding, screw extrusion and blown film extrusion techniques. 

Monoaxially and biaxially oriented films of fluoropolymer are made by melt extrusion of the resin into flat webs or tubes. The main function of orientation is to enhance the mechanical properties of the film such as tensile break strength and tear resistance. The decision to orient is usually made according to the requirements of the end use for mechanical properties. All process surfaces that contact molten fluoropolymers must be corrosion resistant because of the formation of corrosive compounds such as HF and HCl from the high-temperature degradation of these plastics. 

Vinylidene Fluoride Hexafluoropropylene Copolymer - Thermoplastic copolymer of vinylidene fluoride and hexafluoropropylene. Has better thermal stability, antistick, dielectric, and antifriction properties, and chemical resistance, but lower mechanical strength at room temperature and creep resistance, compared to incompletely fluorinated fluoropolymers. Processing by conventional thermoplastic techniques is difficult due to its high melt viscosity. Uses include chemical apparatus, containers, films, and coatings. Also called TAM... 

Since the conditioning time required to clear melt fracture in a blown-film line essentially equals lost bags and lost value, any Improvement is welcome. Thus Ampacet has proposed new fluoropolymer processing aids that clear melt fracture faster than "first-generation" additives. 

Fluoropolymer-based additives are very useful, offering low temperature processability, chemical resistance, weatherability, self-extinguishing, and flexibility. Available as powders, pellets, dispersions or master batch concentrate (at additions of 250-1000 ppm), they are designed for use in PO film extrusion to eliminate melt fracture or problems arising from die build-up when running PO polymer with fillers and pigments [17, 59]. 

Fluoropolymers produce a transparent film fabricated in thin gauges ranging typically from 0.012 mm to 0.040 mm thickness. The film is produced by stretching an extruded sheet or tube in two orthogonal directions—the machine direction and the transverse direction. Stretching is carried out at a temperature below the melting point of the polymer and results in a partial orientation of polymer molecules in the direction of stretch. In principle, biaxially oriented film is isotropic—its properties are the same in both the machine and transverse directions. In practice, film produced by the tenter process tends to be more highly oriented in the machine direction whereas the blown process produces a film that is more nearly isotropic. 

Fluoropolymer additive was used in blown film made out of metallocene linear low density polyethylene. This additive improves processability and eliminates melt fracture. The fluoropolymer additive presence was associated with a substantial increase of dart impact strength (84%), and it had no effect on tear strength. Some slip agent of undisclosed composition was also used. With 3 wt% slip additive, the dart impact strength was reduced to the same level it had without fluoropolymer additive. The tear resistance was not affected by the addition of a slip agent. ... 

It is noticeable that the above mechanism is based on studies of fatty acid amides while other slip agents are also used for various purposes related with reduction of coefficient of fnction. Fluoropolymer additives, for example, are used to improve film extmsion in which they act in a similar manner during process as amides act in the final film. Fluoropolymer additive is also not compatible with polymer matrix. During extrusion it migrates to the surface of metal and forms film which has pronounced effect on production parameters. It reduces melt fraction, viscosity, shear rate, and gate pressure. This makes production faster and eneigy use lower. Some of these additives are developed in such a manner that they migrate only in a molten state but are immobilized within material after material solidifies. This makes them essentially absent from the film surface which in some post process operation is an important requirement. ... 

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