Chain Extension of Recycled PET by Reactive Extrusion

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.