UV-Visible spectrophotometry for determination of conjugated polyene structures in modified Poly (vinyl chloride) with NaOH solution

Chemical modification of poly (vinyl chloride) (PVC, Mn=79,950) by NaOH in an equal mixture of ethylene glycol (EG) / N,N-dimethylformamide (DMF) solvents in 150 °C have been investigated. The reaction of PVC with NaOH was found to result in the substitution of Cl in PVC with OH- from solution and also straight elimination of HCl (dehydrochlorination), both of which lead to dechlorination of PVC. Due to HCl elimination from PVC, unsaturated C=C bonds was formed in polymer chains. The formation of conjugated polyene structures can be well recognized from gradual changes in product colors from white (PVC) to brown for sample c. The results of UV-Visible analysis show that with increasing the degree of dechlorination, the concentration and length of conjugated bonds was increased

Keywords:

PVC , dehydrochlorination , conjugated polyene structures , UV-Visible