Radiation aging and chemi-crystallization processes in polyoxymethylene

► Polyoxymethylene radiochemical degradation is used to study the effects of molar mass changes in the crystallinity. ► Chemi-crystallization is evidenced by an increase in the crystallinity ratio and a decrease in the amorphous layer. ► Simple models, derived from Rault's theory, are used to predict the crystalline structure from molar mass values.