Thermal properties fluoroplastics

Fluoroplastics Excellent electrical, chemical, and thermal properties. CFCI3 lowest MVTR of any transparent film, LOX (liqnid oxygen) compatible and flexible at cryogenictemperatnres nses packaging of hygroscopic pharmacenticals. 

Every plastic manifests a limited shear resistance, determined as the permissible shear rate exceeding this value causes mechanical destruction and tearing of molecules of the plastic as a result of excessive internal friction, which has a bearing on the mechanical, electrical or thermal properties of the moulded part. The plastics with the greatest shear resistance are those of low viscosity, e.g., readily fluid versions of PP and PE, PA, etc. Low shear resistance is a feature of plastics like PP (of a high viscosity), PC, PSU and PPS. PVC, CA, CAB, EVA, POM and fluoroplastics have a particularly low shear resistance. 

Thermal and physical properties of fluoroplastics (typical values) PTFE PCTFE PVDF PVF PE-CTFE PE TFE... 

The description of the physical properties of fluoroelastomers is necessarily less precise than that of fluoroplastics because of the major effect of adding curatives and fillers to achieve useful cross-linked materials of a given hardness and specific mechanical properties Generally, two parameters are varied increasing cross-link density increases modulus and decreases elongation, and raising filler levels increases hardness and decreases solvent swell because of the decreased volume fraction of the elastomer In addition to these two major vanables, the major determinants of vulcanizate behavior are the chemical and thermal stabilities of its cross-links The selection of elastomer, of course, places limits on the overall resistance to fluids and chemicals and on its service temperature range... 

This section presents information and data related to thermal stability of resins and basic properties as a function of temperature. Thermal stability of fluoropolymers has special importance because of the high processing temperatures required by these thermoplastics and the toxic and corrosive nature of their degradation products. Fluoroplastics have useful properties at temperature extremes above and below ambient conditions. 

Fluoroplastics are used in a large number of applications that involve operations at temperature extremes because of the ability of these plastics to withstand very high or low temperatures. A popular method of testing a part is based on monitoring the physical or mechanical properties, such as tensile strength and break elongation, as a result of thermal exposure over time. To check the impact of process-... 

Failure of parts, irrespective of plastic t5 e, is an inevitable fact of the operation of chemical plants. Fluoropolymers are no exception in spite of their excellent chemical, thermal, and mechanical properties. These plastics form the processing surfaces of equipment where they are exposed to the most aggressive and corrosive chemicals. The repeated exposure of fluoroplastics to these chemicals, in addition to other factors, can affect the integrity and surface quality of the parts. The chapters dealing with properties and part fabrication techniques of fluoropolymers should be consulted extensively. An understanding of the limitations of fluoropolymers and flaws created by fabrication methods is required for successful failure analysis of parts. 

Fluoropolymers Polymers prepared Irom unsaturated fluorine-containing hydrocarbons. Has good chemical resistance, weatherability, thermal stability, antiadhesive properties, low friction, and flammability, but low creep resistance, strength, and difficulty processing. The properties vary with the fluorine content. Processed by extrusion and molding. Used as liners in chemical apparatus, in bearings, films, coatings, and containers. Also called Fluoroplastics. 

ETFE is a fluoroplastic with excellent electrical and chemical properties. It also has excellent mechanical properties. ETEE is especially suited for uses requiring high mechanical strength, chemical, thermal, and/or electrical properties. The mechanical properties of ETEE are superior to those of PTEE and EEP. ETFE has ... 

Ethylene chlorotrifluoroethylene copolymer (ECTFE, E/CTFE) n. A fluoroplastic with good mechanical, thermal, electrical, processing, and resistance properties. 

Perfluorocyclobutane (PFCB) polyaryl ethers are one such class of partially fluorinated polymers which combine the processability and durability of engineering thermoplastics with the optical, electrical, thermal, and chemical resistant properties of traditional fluoroplastics. Developed originally at The Dow Chemical Company" in Freeport, TX, PFCB polymers are prepared by the radical mediated thermal cyclopolymerization of trifluorovinyl ethers (Figure 1) and have, to date, provided a variety of thermoplastic and thermosetting materials possessing a tunable range of... 

PTFE Fluoroplastic n Polytetrafluoroethylene is prepared by free radical polymerization of tetrafluor-oethylene in aqueous systems with persulphate or peroxide initiators to give granular or dispersion polymers. The polymers have exceptionally high thermal and thermo-oxidative stability and are completely solvent resistant. PTFEs are tough, relatively flexible materials which have outstandingly good electrical insulation properties as well as unusually low coefficients of friction. 

The consumption of fluoroplastics has increased over the years as technological advancement has required the properties of fluoropolymers. The applications fluoropolymers, in general, span all facets of human life, from household uses to the aerospace and electronic industries. Properties (Table 1.2) of useful fluoropolymers lead directly to applications their chemical resistance, thermal stability, cryogenic properties, low coefficient of friction, low surface energy, low dielectric constant, high volume and surface resis-... 

Carbon, fluorine, and hydrogen are the major elements that form the perfluorinated and partially fluori-nated fluoropolymers. The presence of fluorine is the main reason that these plastics have many special properties, which surpass those of most polymers. The desirable properties span across mechanical, tribological, electrical, and thermal characteristics of these polymers in addition to chemical resistance. Increased fluorine content of the fluoropolymers enhances these properties. Consequently, perfluoropolymers should be sought out when ultimate chemical resistance, electrical properties, etc., are required. This chapter concentrates on presenting the key properties of fluoropolymers. Properties of fluoroplastics films can be found in Ch. 6 and Appendix VI. 

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