Resonance Raman spectroscopic studies on dehydrochlorinated stretched poly(vinyl chloride)

Resonance Raman spectroscopy has been used to assess the effect of streching on the formation of conjugated polyenes during the thermal dehydrochlorination of poly(vinyl chloride). Two samples, a commerical mass polymer and a material prepared at −30°C, have been examined, unplasticised and plasticised, at different draw ratios. Stretching prior to dehydrochlorination leads to an increase in the length of the polyene sequences, the effect being more marked with the low temperature polymer and with increasing draw ratio. Stretching after dehydrochlorination has no significant effect on the polyene distribution. These observations are consistent with the occurrence of chain orientation and alignment during stretching; this reduces the incidence of cross‐linking between polyene sequences in adjacent chains and leads to an increase in the average sequence length.