Gas permeation resistance of various grades of perfluoroalkoxy-polytetrafluoroethylene copolymers

The permeation resistance of various grades of perfluoroalkoxy (PFA)/polytetrafluoroethylene (PTFE) copolymers was tested. Specimens were compression molded using two different cooling techniques: a faster one (ice water quench) and a slower one (press cooled). Permeability, diffusion, and solubilit...

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Bibliographic Details
Published in:Journal of applied polymer science 2009-01, Vol.111 (1), p.141-147
Main Authors: Monson, L, Moon, Sung In, Extrand, C.W
Format: Article
Language:English
Subjects:
diffusion
fluoropolymers
perfluoroalkoxy (PFA)
polytetrafluoroethylene (PTFE) copolymer
structure-property relations
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Summary:The permeation resistance of various grades of perfluoroalkoxy (PFA)/polytetrafluoroethylene (PTFE) copolymers was tested. Specimens were compression molded using two different cooling techniques: a faster one (ice water quench) and a slower one (press cooled). Permeability, diffusion, and solubility coefficients were measured for hydrogen, nitrogen, and oxygen gases. The slow cooled samples always showed much better permeation resistance than those cooled quickly, demonstrating that process can be as important as polymer grade in determining the ultimate permeation resistance of PFA. For a given cooling method, molecular mass (chain length) had no appreciable affect on the permeation resistance. On the other hand, PFA grades with increased comonomer content appeared to have slightly diminished permeation resistance whereas grades with PTFE filler had better permeation resistance. Differences in permeation resistance were attributed to variation in crystallinity arising from differences in molecular architecture and processing.
ISSN:0021-8995
1097-4628
DOI:10.1002/app.28858