Supercritical Fractionation of A Perfluorinated Copolymer
| Autor: | Mark A. McHugh, Cynthia A. Mertdogan, Dennis J. Walls, William H. Tuminello, Howard G. Barth |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | International Journal of Polymer Analysis and Characterization. 4:231-246 |
| ISSN: | 1563-5341 1023-666X |
| DOI: | 10.1080/10236669808009712 |
| Popis: | A perfluorinated copolymer, poly(tetrafluoroethylene-co-19, 3 mol % hexafluoropropylene), is fractionated using supercritical SF6. The fractionations arc performed isothermally at 163°C using an increasing pressure profile to obtain gram-sized fractions that have molecular weight distributions that are narrower than that of the parent copolymer. The fractionation pressure is increased in increments of 34 bar from 276 to 683 bar. The parent material and the fractions are characterized using SEC and FTTR spectroscopy. The first seven samples, eluting between 276 and 552 bar, show a trend of increased molecular weight of the fraction with increasing fractionation pressure. Above 552 bar, the molecular weight of the remaining fractions decreases with increasing fractionation pressure. Although these last fractions do not differ in hexafluoropropylene content, they do differ in the type and concentration of their end groups. In particular, the fractions that eluted at pressures greater than 552 bar co... |
| Databáze: | OpenAIRE |
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