Mechanisms involved in the photolysis of thermally oxidized polyolefins during processing

7 Mechanisms involved in the photolysis of thermally oxidized polyolefins during processing 

All commercial polyolefins always contain a small amount of olefinic unsaturation, of which vinyl is the most important in high density polyethylene (HDPE) and vinylidene in low density polyethylene (LDPE)  

These groups, like unsaturation in polydiene polymers become involved in oxidative reactions during a typical processing operation [125, 414, 1920]  

Allylic hydroperoxides (3.11) formed from auto-oxidation at low temperatures (50-90 °C) and thermal oxidation during processing (130-190 °C) differ substantially in the rates of decomposition, and initiation of degradation processes  

Hydroperoxide groups formed at low temperatures in polyethylene (85-95°) and propylene (50-70 °C) are isolated from each other, and when UV irradiated very slowly, they photodecompose and have virtually no photo-initiating effect [145, 149, 778, 2277], 

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