Abstract: Recycled poly(ethylene terephthalate)（PET）bottle flakes were prepared by melt extrusion, and the chain extension was performed during the extrusion process by addition of methylene diphenyl diisocyanate (MDI), pyromellitic dianhydride (PMDA) and MDI/PMDA mixture as chain extenders. The results indicated that the intrinsic viscosity of recycle PET reached a maximum value of 0.87 dL/g when using PMDA as a chain extender, whereas the ecycle PET only achieved an intrinsic viscosity of 0.68 dL/g by use of MDI chain extender. Furthermore, when using a mixture of MDI and PMDA for the chain extension of recycled PET, the intrinsic viscosity research 0.62~0.68 dL/g. The crystallization temperature of recycled PET decreased due to the addition of PMDA or MDI, whereas its crystalline enthalpy increased. However, the crystallization rates always exhibited little change with the addition of chain extenders.

Key words: recycle, polyethylene terephthalate, chain extender, crystallization