Hydrolysis of post-consume poly(ethylene terephthalate) with sulfuric acid and product characterization by WAXD, 13C NMR and DSC

Post-consume PET was hydrolysed with commercial sulfuric acid (96%) with varying reaction times (5-120 min). The structure of the material obtained was analysed by 13C NMR, DSC, and WAXD and the results were correlated with reaction time. 13C NMR shows a decrease in chain size with reaction time and an increase in the number of carboxyl groups at the end of the chains. The correlation of DSC and WAXD data indicates the presence of structures of different sizes and an increase in crystallinity with reaction time. The structure of the samples hydrolysed for 5-60 min is less ordered than those of the samples hydrolysed for 60-120 min because the amorphous phase is predominantly quickly dissolved. Dissolution of the crystalline phase is favoured by the increase in reaction time. In this process, the crystalline memory retained in the dissolution of the crystalline phase behaves as nucleation sites which form smaller and more ordered structures compared to those obtained with shorter reaction times.