Reactive extrusion of recycled poly(ethylene terephthalate) with polycarbonate by addition of chain extender

Poly(ethylene terephthalate) (PET) resin is one of the most widely used engineering plastic with high performance, but the poor impact strength limits its applications for the notch sensitivity. In this research, toughened PET alloy was prepared by blending recycled PET with polycarbonate (PC) and MDI (methylenediphenyl diisocyanate). Intrinsic viscosity and melt viscosity measurements proved increase of the molecular weights of PET via chain-extending reaction. FTIR and DMA results proved that some PET-PC copolymers were produced and the compatibility of PET phase and PC phase was improved. In addition, the reaction induced by MDI also affected the crystallization behaviors of PET, as observed from DSC results, and the crytallinity of PET decreased with the increase of MDI content. For all of these effects of MDI of increasing of molecular weight, improving of compatibility, and limiting the crystallization behaviors of PET/PC alloy, the notched-impact strength was greatly improved from 17.3 to 70.5 kJ/m. (c) 2007 Wiley Periodicals, Inc.