Reactions of Hydroperoxide Species That Lead to Backbone Degradation

Reactions of Hydroperoxide Species That Lead to Backbone Degradation 

The short polyenes that occur in PVC by elimination of HCl (Eq. 3) are another example of chromophore formation.  

These polyenes readily absorb near-UV and visible light, which is why unstabihzed PVC tends to yellow on exposure to UV radiation. Subsequent photochemical reactions with oxygen to form hydroperoxy species then occur as shown in scheme 4. 

One final example serves to illustrate that backbone cleavage can occur directly from the hydroperoxy species itself. On the basis of resonance Raman studies with polyamides, Valentini et al. proposed the chain scission sequence involving the hydroperoxide species shown in scheme 5.  

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