Poly(ethylene terephthalate)/polypropylene reactive blends through isocyanate functional group

To evaluate the compatibilization effects of an isocyanate group on poly(ethylene terephthalate)/polypropylene (PET/PP) blends through a reactive blend, PP grafted with 2‐hydroxyethyl methacrylate‐isophorone diisocyanate (PP‐ g ‐HI) was prepared and blended with PET. In view of the blend morphology, the presence of PP‐ g ‐HI reduced the particle size of the dispersed phase by the reduced interfacial tension between the PP and PET phases, indicating the in situ copolymer (PP‐ g ‐PET) generated during the melt blending. The DSC thermograms for the cooling run indicated that the PET crystallization in the PP‐ g ‐HI rich phase was affected by the chemical reactions of PET and PP‐ g ‐HI. The improved mechanical properties for the PET/PP‐ g ‐HI blends were shown in the measurement of the tensile and flexural properties. In addition, the water absorption test indicated that the PET/PP‐ g ‐HI blend was more effective than the PET/PP blend in improving the water resistance of PET. The positive properties of PET/PP‐ g ‐HI blends stemmed from the improved compatibilization of the PET/PP blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1056–1062, 2001