Polystyrene in the absence of oxygen

The primary process in UV (254 nm) irradiation of polystyrene in vacuum is the formation of polymer alkyl radical (3.74), double bonds in the polymer backbone (825 cm out-of-plane vibration of the C—H bond) and evolution of hydrogen [833, 835, 2286]  

A septet line ESR spectrum (Fig. 3.47a) is direct evidence for the formation of polymer alkyl radical (3.74) [492, 1360]. When the sample, irradiated by UV in vacuum is next exposed to air, a new asymmetric ESR spectrum is formed (Fig. 3.47b). This signal can be assigned to the formation of the polymer peroxy (PO 2) radical (cf. section 3.11.1.4) [980, 1360]. 

During UV irradiation of polystyrene in vacuum, the sample becomes insoluble (crosslinked) and slightly yellow coloured (due to the formation of 

Polystyrene blends with Polyethylene Poly(vinyl chloride) 

Poly(acrylonitrile-co-butadiene-co-styrene) and poly(vinyl chloride) 

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