Recycling of fluoropolymers

At present, some 4000 metric tons of fluoroplastics are recycled annually [7]. 

in Modern Fluoropolymers (Scheirs, J., Ed.), John Wiley Sons, New York, p. 340 (1997). 

Van der Walt, I. J., U.S. Patent 6,797,913 (September 2004) to South African Nuclear Energy Corporation. 

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Disposal, and Recycling of Fluoropolymers, covers these topics and provides additional references. 

This chapter contains information about safe processing of fluoropolymers and safe handling of parts made from these plastics. The material in this chapter is in no way intended as a replacement for the specific information and data supplied by the manufacturers of fluoropolymer resins and parts. A source of information that is frequently referenced in this chapter is The Guide to Safe Handling of Fluoropolymers Resins, published by The Society of Plastics Industry, Inc. Disposal and recycling issues are also reviewed. 

Recovery/Removal and Recycling of Perfluorinated Acids from Fluoropolymers and Industrial Waste Streams In the last decade of the twentieth century, PFOS and PFOA as well as other fluorinated substances came under scrutiny because they are environmentally persistent and potentially bioaccumulative. Analytical developments resulted in the detection of these substances widespread in the environment [28]. Triggered by these environmental concerns, as well as by the high price of the fluorinated emulsifiers, methods were developed which allowed effective recovery and recycling of fluorinated emulsifiers from these industrial production processes. 

There are quite a variety of different sources and different types of fluoropolymers for recycling purposes. Consequently, one has to consider these issues from various... 

In some cases, used perfluorinated fluoropolymers (e.g., PTFE, PFA) are recycled by special cleaning processes and are ending up in the Repro-PTFE or micropowder-PTFE-market. Perfluorinated thermoplasts (e.g., PFA) are reused in applications where the quality requirements (e.g., lot traceability) are much lower. Overall, the lion s share of used fluoropolymers is, however, ending up in landfills, in incineration plants, or in blast furnaces. Communal waste incinerators can tolerate only very limited amounts of fluoropolymers due to the high corrosion due to hydrofluoric acid formed in the process. 

Ti02/fluoropolymer composite nanofibers by combining the electrospinning technique and hydrothermal complex-precipitation [115], The obtained Ti02 nanoparticles were well dispersed on the surface of fluoropolymer nanofibers. The photocatalytic activity of the as-prepared TiOo/fiuoropolymer composite nanofibers is higher than that of P25 nanoparticles (Fig. 15.10). Moreover, the good recycling and stability of the composite nanofibers enable them to be applicable in the wastewater treatment. 

Metal-organic complexes and amorphous fluoropolymers used as catalysts in many organic syntheses exhibit excellent solubility in ScCO [9]. Fluoropolymers such as poly(chlorotrifluoroethylene), fluorinated polyacrylates, copolymers of fluorinated acrylates with methacrylate, n-butyl acrylate, styrene, ethylene, etc. which are used to enhance the solubility of the catalyst are also reported to be highly soluble in SCCO2 [9]. Temperature and pressure dependent catalyst solubility not only enhances its activity, but also permits easy recovery and recycle of the catalyst at the end of the reaction. It is possible to precipitate the catalyst and sometimes the product by suitable adjustments in temperature and pressure, and integrate reaction and separation. 

Fabrics that cannot be finished with aqueous fluoropolymer dispersions can be finished by spray application of a fluoropolymer dispersed in a volatile solvent, such as stabilized trichloroethylene [150] or tetrachloroethylene [151]. After spraying, fabrics pass directly from the spray booth into a dryer heated at 38-66°C. The finish is cured for 60 s at 150°C or at a lower temperature if the fabric cannot tolerate heating at 150°C [150]. Equipment has been built for continuous pad-dry-heat application of fluoropolymers from a volatile solvent, which is recovered almost completely and recycled [151]. The use of volatile solvents has caused environmental concerns. 

In general, PVDF is one of the easiest fluoropolymers to process and can be easily recycled without affecting its physical and chemical properties. As... 

All aspects of the fluoropolymers including monomer synthesis, polymerization, properties, applications, part fabrication techniques, safety in handling, and recycling are discussed. Homopolymers and copolymers of vinylidene fluoride, all melt processible, have been covered in Volume Two because of the close... 

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