Thermal and oxidative effects in polyethylenes above 200°C

There is considerable literature on the behavior of polyethylene below 200°C and above 400°C. This paper presents results on both high and low density polyethylene between 2000 and 400°C, a range of practical import for various fabrication and processing steps. Practical exposure times may be short and the experimental procedures were designed to give meaningful results for times as low as 1 min. The principal effects are chain‐session and oxidation. Session was isolated by applying an atmosphere of pure nitrogen and proved uite shlow at 300°C but rapid at 400°C. The course of scission and produces discoloration, odor, and rising carbonyl content. A brief discussion is given of the role of diffusion in oxidation.