Effects of maleic anhydride on degradation of PVC during pyrolysis

The effect of maleic anhydride on the chemical structure of solid pyrolyzate obtained from PVC pyrolysis was investigated. It was found that by mixing maleic anhydride with poly(vinyl chloride) prior to the pyrolysis, the dehydrochlorination of the PVC was retarded. On the other hand, by sequentially adding maleic anhydride during the pyrolysis of poly(vinyl chloride), new FT-IR peak at 1858 and 1771 cm−1 corresponding to a carbonyl group of the anhydride were observed, owing to the chemical reaction between polyene intermediate and the anhydride. Besides the dehydrochlorination of PVC and the reaction between polyene intermediate and the anhydride, it is apparently that cross-linking of the polyene intermediate also occurred as evidenced from gel content analysis. The results showed that gel content increased with increasing reaction temperature and time.