A physicochemical route for compensation of molecular weight loss during recycling of poly(ethylene terephthalate)

This work is aimed to undertake the simultaneous effect of chain extension (chemical modification) and solid-state polymerization (SSP) on the structural properties of recycled poly(ethylene terephthalate) to compensate the molecular weight (MW) losses caused by thermal degradation. This hybrid technique was qualified by tracking changes in the MW, intrinsic viscosity (IV), and concentrations of hydroxyl and carboxylic groups of various samples containing different concentrations of chain extender that experienced different residence times (2, 4, 6, 8, and 10 h) and different SSP process temperatures (190, 200, and 210 degrees C). It was found that at high concentrations of chain extender, thermal degradation is facilitated owing to the lack of functional groups, as witnessed by a sharp drop in the MW and IV. The re-recycled poly(ethylene terephthalates) experienced chemical modification followed by SSP physical treatment and revealed a rise in MW and IV. Accordingly, the synergistic effect of hybrid modification in comparison with the individual chemical modification was highlighted. J. VINYL ADDIT. TECHNOL., 22:387-395, 2016. (c) 2015 Society of Plastics Engineers