The chemical reactions occurring during the melt blending between a dibutyl maleate functionalized polyolefin (POF) and poly(ethylene terephthalate) (PET) in the presence of Zn(OOCCH3)(2) (.) 2H(2)O were studied as a function of blending conditions, such as the preliminary drying of PET, the presence of a nitrogen flow during blending and the time of blending. The selective extraction of POF/PET 30/70 by weight blends to remove unreacted PET and the determination of its molecular weight by viscosimetric measurements allowed to evaluate both the grafting points' number and the molecular weight of PET. In this way the impact of degradation of PET onto its grafting by transesterification onto POF was investigated. The examined blending conditions were shown to affect both PET degradation and POF-PET copolymer formation. In order to correlate data about macromolecular and morphological structure with the final properties of the blends, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests were also carried out. (c) 2007 Elsevier Ltd. All rights reserved.