Polyethylene bond dissociation energy

These data show that the dissociation energy of the urethane-type bonds is lower than that of -C-C- bonds from polyethylene or polypropylene. It is also two times lower than the dissociation energy of the bond from the polyamide chain. In this last case, the energetic barrier that must be overtaken in order as a elementary craek to appear is higher due to the supplementary orientation of the amorphous domains of fibres, realised by forced orientation during stretching. 

Polymers, particularly polyolefins, start to decompose at significantly lower temperatures under the same conditions because some weak sites, such as unsaturated groups and branching points, deaease the dissociation energy of C-C bonds." As an example, the thermal degradation of linear polyethylene in ox5 en-firee environment starts with random scission of the polymer chains preferentially in allylic positions... 

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