a biodegradable polymer composition having good resistance to thermal decomposition , wherein it is possible to control the weight - average molecular weight to within 30 % of the initial molecular weight after molding and radiation sterilization , by adding a free radical scavenger to the biodegradable polymer . biodegradable polymer compositions of the invention , which withstand thermal and radiation decomposition are effective for medical and many industrial uses . moreover , this inventive method is applicable for the treatment of many non - biodegradable polymers such as nylon or polypropylene which are subjected to thermal casting and radiation sterilization .