Vicinal hydroperoxides decomposition

Figure 2 Intramolecular propagation and formation of vicinal hydroperoxides in PP and their decomposition.

In polyethylene the proportion of vicinal hydroperoxides is lower than in PP and random chain scission is initially the dominant process. However, a variety of low molar mass oxidation products are formed via vicinal hydroperoxides (Scheme 1). The alkoxyl radicals formed by decomposition of the hydroperoxides contain weak carbon-carbon bonds in the a positions to the hydroperoxide groups which lead to the formation of low molecular weight aldehydes and alcohols that further oxidise rapidly to abiotically stable carboxylic acids. These are biodegradable species, similar to those formed by hydrolysis of aliphatic polyesters and they provide an environment for rapid biofilm formation (Section 5.5). 

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