Thermal and Ultraviolet Stability of Polyoxymethylene

Abstract

We have studied the thermal and ultraviolet oxidation of polyoxymethylene (Delrin) film.
The changes in tensile strength, infrared absorption spectrum, melt flow rate, specific gravity and crystallinity were remarkable by the higher energy irradiation of ultraviolet ray 254mμ, 316mμ and heat treatment at 170°C, while these changes were slow by the lower energy irradiation of ultraviolet ray 354mμ and 380mμ.
The mechanism of degradation was considered as the random and/or the end scission of polyoxymethylene chain by oxidation.
We found that higher molecular weight polymer was more stable than lower one in high energy ultraviolet ray irradiation and heat treatment at 170°C and we also observed the increase of crystallinity by oxidation.