Vinyl groups, decay

Various authors—for example, Dole, Milner, and Williams (15) and Lyons (25)—have suggested that the decay of vinyl groups initially present in some types of high density polyethylene involves an end-linking process, these authors disagreeing only about the mechanism involved. If such were the case, some difference in solubility or elastic behavior above 140 °C. would be expected between low and high density poly-... 

Free radicals are also produced by chain scission during deformation of polyethylene and FT-IR has been used to follow this process 237). The polyethylene samples were unaxially drawn and the resultant spectra corrected for orientation. An increase in the vinyl and methyl end groups created by decay of the free radicals occured in going from draw ratios of 5 to 20 44). A similar study involving deformation was made of polystyrene 246) and a comparison demonstrated between the results of thermal and mechanical degradation 24S. ... 

The backbone structural feamre of two hydrogen atoms per carbon leads to several unique responses to irradiation including hydrogen gas evolution, formation of trans viny-lene unsaturation, the decay of vinyl end groups and extremely high crosslinking efficiency. 

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