Perfluorinated Polymers

Abstract

This article provides information on several perfluorinated polymers; their manufacture, properties, fabrication, and applications are discussed. Polytetrafluoroethylene (PTFE), known as Teflon PTFE, a perfluorinated straight‐chain high molecular weight polymer, is commercially important because of its chemical inertness, heat resistance, excellent electrical insulation properties, and low friction coefficient. PTFE is used in the chemical processing industry for structures, linings, seals, and hose or tubing. Perfluorinated ethylene–propylene (FEP), a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), has a melt viscosity low enough for conventional melt processing. The extrusion grade is suitable for tubing, wire coating, and cable jacketing. Copolymers of ethylene and tetrafluoroethylene (ETFE) and specifically modified ETFE are commercially valuable because of their good tensile strength, moderate stiffness, and outstanding impact strength. The general‐purpose resin is used for insulating and jacketing low voltage power wiring for mass transport system, wiring for chemical plants, and control and instrumentation wiring. Perfluoroalkoxy (PFA) fluorocarbon resin copolymers contain a fluorocarbon backbone in the main chain and randomly distributed perfluorinated ether side chains. General‐purpose grade applications include tubing, molded parts, and insulation for electrical wire and cables. Some grades of this polymer are suitable in semiconductor manufacturing, fluid handling systems, and instrumentation for precise measurements of fluid systems. Copolymers of tetrafluoroethylene–perfluorodioxole are perfluorinated amorphous polymers, known as Teflon AF, having high temperature stability, excellent chemical resistance, high transparency, and low refractive index. They are used in antireflective coatings, low dielectric coatings, pellicles in electronic chips, plastic optical fiber, and in gas separation membranes.

Polytetrafluoroethylene Ingestion as a Way to Increase Food Volume and Hence Satiety Without Increasing Calorie Content

“…Aqueous dispersions of PTFE typically have an average particle size below a micron 40 ; the most common PTFE aqueous dispersion has an average particle size of about 0.2 µm. 41 Despite the small particle size, large ingestion amount, and extensive exposure length in these feeding trials, the data indicates that the particles did not pass from the GI lumen to the blood. If the particles passed to the blood, via the portal circulation, they would be expected to accumulate in the liver.…”

Rising Perfluorocyclobutane (PFC-318, c-C4F8) Emissions in China from 2011 to 2020 Inferred from Atmospheric Observations

“…Previously, PFC-318 emissions were assumed to be predominantly caused by its use for plasma etching in the semiconductor industry, but highly efficient abatement due to modern emission controls can reduce emissions from the semiconductor and microelectronics industry by up to 90%, making PFC-318 emissions from this industry likely relatively low . Another potentially noteworthy source of PFC-318 is the production of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) monomers. − The primary method for preparing TFE and HFP monomers is through the pyrolysis of hydrochlorofluorocarbon-22 (HCFC-22, CHClF 2 ). In this process, PFC-318 is formed as a byproduct of the dimerization of TFE.…”

“…In this process, PFC-318 is formed as a byproduct of the dimerization of TFE. By controlling the dimerization process of TFE, PFC-318 can be generated, and copyrolysis of PFC-318 and TFE may also lead to the formation of HFP or PFC-318. ,− , Mühle et al showed that PFC-318 emissions were highly correlated with the use or production of HCFC-22 feedstock, observed both on a global scale and within developing (Article 5 of the Montreal Protocol, A5) countries. Almost all global feedstock production of HCFC-22 is used to produce TFE and HFP, which are subsequently used to produce polytetrafluoroethylene (PTFE) and other fluorinated polymers and compounds, during which PFC-318 is formed as a byproduct and then likely emitted into the atmosphere.…”

Ultralow wear Perfluoroalkoxy (PFA) and alumina composites

“…However, one disadvantage of PTFE is its manufacturability. PTFE has near infinite melt viscosity (near zero melt flow rate) [26] which prevents the use of screw injection molding. Thus, PTFE parts are typically manufactured using compression molding and sintering, which can only create simple geometries.…”

“…Complex geometries must be machined after the part has been sintered, which adds additional cost to the manufacturing process. However, perfluroalkoxy polymer (PFA) is a perfluoropolymer with properties similar to PTFE, but with a higher melt flow rate (~14 g/10 min) [26]. PFAs are a group of copolymers of TFE with small amounts of various types of perfluoroalkylvinyl ethers (alkyl = methyl [PMVE], ethyl [PEVE], propyl [PPVE]) which along with a chain transfer agent, decrease the molecular weight and increase the melt flow rate enough to enable injection molding (see Figure 1 for chemical structure) [27].…”