It was confirmed that the trans chains of PE molecular chains, to which Li2CO3 was added (PE with Li2CO3), transform to gauche chains, and as a result, maltese crosses disappeared. We investigated changes in the suscep-tibility of PE to thermal oxidation with the transformation of PE molecular chains to gauche ones. Furthermore, the study by Py-GC method on the gases evolved by the oxidation of PE showed that the amount of CO gas evolved in PE with Li2CO3 is reduced compared to PE without Li2CO3 , indicating that the addition of Li2CO3 to PE is presumed to have the retardation effect for the oxidation. The amount of CO gas evolved in PE with Li2CO3 by heat treatment at 110°C for 1 to 5hr was less than that of PE without Li2CO3. This result also seems to be originated in the retardation effect due to Li2CO3 Among PE with Li2CO3 examined in this study, the smallest amount of CO gas evolved was recorded for PE to which Li2CO3 of 1.0 part per hundred resin was added, so it is expected to have the largest retardation effect for the oxidation.
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