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The Influence of the Irradiation Temperature on the Ratio of Chain Scission to Branching Reactions in Electron Beam Irradiated Polytetrafluoroethylene (PTFE)

✍ Scribed by Uwe Lappan; Uwe Geißler; Ulrich Scheler

Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
165 KB
Volume
292
Category
Article
ISSN
1438-7492

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✦ Synopsis

Abstract

Polytetrafluoroethylene (PTFE) films have been irradiated by electron beam in vacuum at various temperatures ranging from room temperature up to temperatures far above the melting temperature. Changes of the chemical structure have been analyzed by ^19^F solid‐state NMR and IR spectroscopy. The concentration of several structures generated by irradiation increases with increasing irradiation temperature up to the beginning of the thermal degradation. The molar ratio of >CF branching points to CF~3~ end groups changes with crossing of the melting temperature. The generation of >CF branching points is accelerated if the PTFE is irradiated in the molten state, where branching reactions become more important.

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Polytetrafluoroethylene powder (PTFE) was exposed to electron beam radiation in presence of air. The irradiation mainly resulted in chain scission and induction of oxygenated groups and radicals as well as unsaturation. The thermal behavior of the irradiated PTFE and the fate of the radicals were st