Physical properties fluoroplastics

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... 

In another example, ] a problem with poor physical properties of molded fluoroplastics was overcome. Transfer molded material was found to have low modulus of elasticity above 150°C and was prone to irreversible cold flow. The solution involved embedding a metal or plastic insert as a core material in the mold. The choice of the core material depended on the end use performance requirements. 

The melt processible fluoroplastics are often desired due to the cost benefits of melt extrusion over paste extrusion. FEP, PEA and specially formulated melt processible perfluoroplastics are used in many of these applications however, in some of these applications, perfluoroplastics may not be the ideal choice. In cases where high cut-through resistance and better tensile properties are required, it is often desirable to employ a partially fluorinated polymer such as ETFE (ethylene-tetrafluoroethylene). ETFE is the copolymer of ethylene and TEE [16] that normally includes an additional termonomer to increase the flexibility required in commercial applications [17]. The increased physical and electronic interactions of the ETFE polymer chain are responsible for the comparatively enhanced physical properties. Additionally, the partially fluorinated polymers may be cross-linked to further improve physical properties. These benefits, however, are obtained at the expense of the unique properties of perfluoroplastics discussed in the Introduction and Overview. 

In another example,1 1 a problem with poor physical properties of molded fluoroplastics was overcome. Transfer molded material was found to have low modulus of elasticity above 150°C and prone to irreversible cold flow. The solution involved embedding a metal or plastic insert as a core material in the mold. The choice of the core material depended on the end use performance requirements. An engineering plastic core was found preferable examples included polyetherether ketone (PEEK), polyphenylene sulfide (PPS), and polyether imide (PEI). Polytetrafluoroethylene bearers were placed in the mold to keep the core material away from the walls of the mold. No special cavity modifications were required. Any hot-melt fluoroplastic could be molded surrounding the insert examples include PVDF, FEP, ETFE, PFA, ECTFE, and PCTFE. 

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-... 

---