THERMAL-STABILITY OF ELECTRON BEAM-IRRADIATED POLYTETRAFLUOROETHYLENE

Polytetrafluoroethylene (PTFE) was subjected to 1 MeV electron beam ir radiation in air. The thermal stability and the degradation fragments of the irradiated polymer were studied in dependence on the radiation dose up to 4 MGy by thermogravimetric analysis coupled with mass spect rometry. The TGA results confirm the known decrease in the thermal sta bility of irradiated PTFE with increasing radiation dose. At the therm al degradation, CO2, HF, and fluorocarbon fragments are evolved from t he irradiated samples. CO2 and HF are formed by decomposition of perox y radicals up to 250 degrees C. In addition, low molecular weight fluo rocarbons are desorbed from the irradiated PTFE. At temperatures above 300 degrees C, CO2 is formed by the decarboxylation of radiation-indu ced COOH groups inside the PTFE. (C) 1997 John Wiley & Sons, Inc.