Chain Extension Of Recycled Pet By Reactive Extrusion

The influence of the drying-time,chain extender kind and content on the intrinsict viscosity ,carboxyl content and crystal capability of the PET was studied carefully using the extenders of Pyromellitic dianhydride(PMDA) , Epoxy resin and the mixture of the both with polycondensation reactive extruder during reactive extrusion processing.Experiments showed that the intrinsict viscosity of the PET was increaseing with the longer drying-time.PMDA and Epoxy resin has an effective chain extending effect,and the effect is better when using the mixture of the both. After the reaction the intrinsict viscosity of the PET increased from 0.45 dl/g to 0.58dl/g, the molecular weight was also increased abviously. The corbosyl content decreased abviorsly and the crystal degree raised when using epoxy resin.With different contents of DOPO-ITA and ODOPB and the mixture of the both as chain extender, reactive extrusion process for recycled PET flakes was conducted by means of a co-rotating twin screw extruder. The results showed: DOPO-ITA has the best effective chain extending effect. The best intrinsict viscosity of the PET is 0.52 dl/g when using the content of DOPO-ITA is 2%. But the intrinsice viscosity of the PET is 0.47dl/g when using ODOPB.The effect is worse than DOPO-ITA.