PET recycling: Evaluation of the solid state polymerization process

ABSTRACT: Many studies have been carried out to makebottle-to-bottle recycling feasible. One of the difficultiesfound is the decrease in the polymer’s molar mass, whichdamages the injection blow molding process. A methodusually employed to increase the molar mass of virgin PETconsists of solid-state polymerization (SSP). In this work, westudied the SSP process applied to post-consumer recycledPET by analyzing the inherent viscosity and amount ofcarboxylic end groups, and the results of dynamic flowrheometry. Although the results show that the recyclingprocess decreases polymer molar mass, and this indicatesdegradative processes, SSP was successful in increasing mo-lar mass in post-consumer recycled PET. This made feasiblebottle-to-bottle recycling. In addition, the parallel plate rhe-ometry technique was powerful in assessing the degradativeprocess and, therefore, that the SSP process was successful. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2117–2123, 2006 Key words: recycling; post-consumer; poly(ethylene tereph-thalate); degradation; solid-state polymerization