RADIATION-INDUCED OXIDATION OF SOLID POLY(ETHYLENE OXIDE) .1. EXPERIMENTAL RESULTS

In the reported experiments, gamma-initiated oxidations of solid poly(ethylene oxide) (PEOP have been carried out at ambient temperatures and the dependence of the rate of oxygen consumption on rate of initiation, O//2 pressure, and crystallinity has been determined. At 25 degree C, the radiation yield G for O//2 absorbed is 117-281, depending on dose rate, and decreases moderately with increasing crystallinity. The principal oxidation products are formate and hemiformal groups, hydroperoxides, and some volatile compounds, mainly formaldehyde and carbon dioxide. The rate of O//2 consumption and formation of products and chain scission are little affected by a change of the temperature in the range minus 23 to plus 55 degree C except for hydroperoxide, the formation of which requires an activation energy of 4 kcal/mole. Experiments with 2,6-di-tert-butyl-p-cresol show that essentially all of the initiating PO//2 multiplied by (times) radicals escape cage termination; G value for formation of the initiating peroxy radicals was estimated from the inhibition period to be 5. 0 plus or minus 0. 3.