Perfluoroalkoxy melting temperature

The melting of a semierystalline or crystalline pol mier exhibits itself as an endothermic peak. The peak temperature is correspondent to the actual melting point of the pol mier. As in DSC, the area under the peak is proportional to the crystalline fraction of the sample. Mixtures of polymers can be characterized by DTA because the melting points of individual pol miers are, for the most part, unaffected by the mixture. Similar pol miers, such as high and low density, are distinguishable by DTA while infrared spectroscopy would not be able to easily resolve such subtle differences. Figure 10.29 shows a thermogram of a mixture of polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymer (PFA). 

PEA are fully fluorinated and melt processible [70,72,93]. They have chemical resistance and thermal stability comparable to those of PTFE. The specific gravity of perfluoroalkoxy resins is in the range of 2.12-2.17 and PFA has an upper continuous use temperature of 260°C. 

One of the disadvantages of PTIE is that it is not melt processable. In 1960 DuPont introduced fluorinated ethylene propylene (FEP), which was chiefly designed to provide melt processability. In 1972 DuPont introduced another fully fluorinated polymer, perfluoroalkoxy (PEA), which is also melt processable, with better melt flow and molding properties than FEP. Although PEA has somewhat better physical and mechanical properties than FEP above 3000°F (1490°C), it lacks the physical strength of PTFE at elevated temperatures and must be reinforced or designed with thickness to compensate for its softness. The heat deflechon temperature of PFA is the lowest of all fluoropolymers. PFA is used to make tubing products. 

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