Abstract: Using pyromellitic dianhydride (PMDA) and epoxy resin as chain extenders, reactive extrusion for recycled PET flakes was carried out in a co-rotating twin screw extruder. The intrinsic viscosity, carboxyl content, and crystallinity of the reaction products were analyzed. It was found that either PMDA or epoxy resin played a good role in chain extending, their combination was more effective. After the chain extending, the intrinsic viscosity of PET increased from 0.45 to 0.58 dl/g. When using epoxy resin, the carboxyl content decreased obviously and the degree of crystallinity increased.

Key words: recycling, polyethylene terephthalate, pyromellitic dianhydride, epoxy resin, chain extension, reactive extrusion