Thermal Degradation and Pyrolysis of Polytetrafluoroethylene

Puts, Gerard Jacobs; Crouse, Philip; Améduri, Bruno

doi:10.1002/9781118850220.ch5

Cited by 7 publications

(4 citation statements)

References 54 publications

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“…The mechanism of PTFE breakdown has been discussed in detail . In summary, a PTFE macroradical may unzip, that is, depolymerize, giving back the monomer species. Ordinarily, the forward polymerization reaction dominates at low temperatures and in an excess of TFE.…”

Section: Properties Of Ptfementioning

confidence: 99%

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

2019

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This Review aims to be a comprehensive, authoritative, and critical review of general interest to the chemistry community (both academia and industry) as it contains an extensive overview of all published data on the homopolymerization of tetrafluoroethylene (TFE), detailing the TFE homopolymerization process and the resulting chemical and physical properties. Several reviews and encyclopedia chapters on the properties and applications of fluoropolymers in general have been published, including various reviews that extensively report copolymers of TFE (listed below). Despite this, a thorough review of the specific methods of synthesis of the homopolymer, and the relationships between synthesis conditions and the physicochemical properties of the material prepared, has not been available. This Review intends to fill that gap. As known, PTFE and its marginally modified derivatives comprise some 60−65% of the total international fluoropolymer market with a global increase of ca. 7% per annum of its production. Numerous companies, such as Asahi Glass, Solvay Specialty Polymers, Daikin, DuPont/Chemours, Juhua, 3F, 3M/ Dyneon, etc., produce TFE homopolymers. Such polymers, both high-molecular-mass materials and waxes, are chemically inert and hydrophobic and exhibit an excellent thermal stability as well as an exceptionally low coefficient of friction. These polymers find use in applications ranging from coatings and lubrication to pyrotechnics, and an extensive industry (electronic, aerospace, wires and cables, and textiles) has been built around them. South Africa, being the third largest producer of fluorspar (CaF 2 ), the precursor to hydrogen fluoride and fluorine, has embarked on an industrial initiative to locally beneficiate its fluorspar reserves, with the local production of fluoropolymers being one projected outcome. As our manuscript focuses specifically on the homopolymerization of TFE (the starting point for all fluoropolymer industries), it will be of considerable use to start-up companies and other commercial entities looking to enter the fluoropolymer market, as well as to end-user companies. The manuscript commences with a short discussion on the synthesis and production of TFE (both at industrial and laboratory scales), including the safety aspects surrounding handling (because that monomer is regarded as explosive if brought into contact with oxygen due to the formation of peroxides), transport, and storage, and then expands into detailed discussions dealing with aspects such as the various additives used (buffers, chain transfer agents, surfactants, etc.), the solvent environment, and the reaction conditions. A further section reports the properties of PTFE with respect to the polymerization conditions as well as an overview on the specialized techniques used to characterize PTFE. Finally, the applications of PTFE in various fields, ranging from electrical insulation to tribological to medical applications, as well as chemically resistant coatings and pyrotechnics, are discussed.

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Section: Properties Of Ptfementioning

confidence: 99%

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

2019

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“…Fluoropolymers, when used as intended under normal, foreseeable use conditions as specified in Table 2 (or "continuous processing temperature") are thermally stable (Puts et al 2014). The fluoropolymer industry has provided significant information on appropriate use of fluoropolymers (SPI 2005).…”

Section: Thermal Stabilitymentioning

confidence: 99%

A critical review of the application of polymer of low concern and regulatory criteria to fluoropolymers

Henry

Carlin

Hammerschmidt

et al. 2018

Integr Envir Assess & Manag

151

133

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Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated substances that are in the focus of researchers and regulators due to widespread presence in the environment and biota, including humans, of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Fluoropolymers, high molecular weight polymers, have unique properties that constitute a distinct class within the PFAS group. Fluoropolymers have thermal, chemical, photochemical, hydrolytic, oxidative, and biological stability. They have negligible residual monomer and oligomer content and low to no leachables. Fluoropolymers are practically insoluble in water and not subject to long-range transport. With a molecular weight well over 100 000 Da, fluoropolymers cannot cross the cell membrane. Fluoropolymers are not bioavailable or bioaccumulative, as evidenced by toxicology studies on polytetrafluoroethylene (PTFE): acute and subchronic systemic toxicity, irritation, sensitization, local toxicity on implantation, cytotoxicity, in vitro and in vivo genotoxicity, hemolysis, complement activation, and thrombogenicity. Clinical studies of patients receiving permanently implanted PTFE cardiovascular medical devices demonstrate no chronic toxicity or carcinogenicity and no reproductive, developmental, or endocrine toxicity. This paper brings together fluoropolymer toxicity data, human clinical data, and physical, chemical, thermal, and biological data for review and assessment to show that fluoropolymers satisfy widely accepted assessment criteria to be considered as "polymers of low concern" (PLC). This review concludes that fluoropolymers are distinctly different from other polymeric and nonpolymeric PFAS and should be separated from them for hazard assessment or regulatory purposes. Grouping fluoropolymers with all classes of PFAS for "read across" or structure-activity relationship assessment is not scientifically appropriate. Integr Environ Assess Manag 2018;14:316-334. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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“…In 2014, we reviewed the thermal degradation and pyrolysis of PTFE in a book chapter, 118 and then Puts and Crouse 109,119 highlighted the fluorinated compounds generated from the pyrolysis of PTFE by heating from 35 °C to 800 °C at 20 °C min −1 in the absence or presence of various metals or salts (Scheme 10). These South African authors found that in the absence of salts, TFE was produced in 98%, while the nature of the salt may induce other released gases (Scheme 10 and Table 5) with the influence of inorganic materials as common oxides of Al, Ga, In, Zn, Cu, Ni, Co, Fe, Mn, Cr, V, Zr and La.…”

Section: Thermal Degradation Of Fpsmentioning

confidence: 99%

Recycling and the end of life assessment of fluoropolymers: recent developments, challenges and future trends

Améduri

Hori

2023

Chem. Soc. Rev.

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Thermal Degradation and Pyrolysis of Polytetrafluoroethylene

Cited by 7 publications

References 54 publications

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

A critical review of the application of polymer of low concern and regulatory criteria to fluoropolymers

Recycling and the end of life assessment of fluoropolymers: recent developments, challenges and future trends

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