| abstract |
Disclosed is a method of treating a free-radical-containing, optionally room-temperature-aged, irradiated, normally solid high-molecular-weight, semi-crystalline propylene polymer material at about from 40°C to 110°C for at least about 10 minutes before being exposed to the higher temperatures that deactivate the residual free radicals therein. Treatment of the polymer at the intermediate temperature causes recombination, and better utilization, of free radicals with the production of more long-chain branching. A two-stage fluid bed process, with a first stage at the intermediate temperature for radical recombination and a second radical-deactivation stage at a higher temperature, is preferred. |