Electron beam irradiation of polytetrafluoroethylene in air: investigations on the thermal behaviour

The influences of annealing on electron beam irradiated polytetrafluoroethylene (PTFE) powder were studied. The onset of thermal degradation is shifted to higher temperatures in comparison to unannealed PTFE as followed closely by thermogravimetry. Above 225 degrees C radiation-induced peroxy radicals are converted to alkyl radicals in a partially reversible process. Simultaneous thermal analyses indicated a release of oxygen containing groups at temperatures distinctly below the degradation temperature of the backbone chains. The behaviour of the carbonyl fluoride and carboxyl groups during annealing in moist air, oxygen atmosphere, and vacuum was monitored by IR spectroscopy. (C) 1999 Elsevier Science B.V. All rights reserved.