Assessment of degradation of plasticized poly(vinyl chloride) films through polyene formation under isothermal conditions

The aim of this work is to assess the degradation of flexible poly(vinyl chloride) (PVC) films produced using orthophthalate based and recently introduced nonorthophthlate plasticizers which have compliance with recent environmental regulations. The plasticized PVC films were subjected to several heat treatments at 85–160 °C up to 420 min. Ultraviolet–visible spectroscopy was utilized to follow polyene formation upon dehydrochlorination of PVC. The amount of polyenes formed exhibited difference amongst the films those plasticized with diethyl hexylphthalate, diisodecyl phthalate, dioctyl terephthalate (DOTP), and diisononyl 1,2‐cyclohexanedicarboxylic acid (DINCH). The order of polyene concentration formed at the utmost level severe heat treatment is in line with the molecular weight ranking from highest to lowest, as the films with diisodecyl phthalate > DINCH > DOTP > diethyl hexylphthalate. Discoloration assessed in terms of yellowness index revealed that the films having recently introduced plasticizers as DOTP and DINCH were competing well with the films having orthophthalate based plasticizers. Scanning electron microscopy images revealed that the longer times for gelation during their production would improve the maturation of the films although they are already coherent and strong. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46092.