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Amine (primary and secondary) functional polypropylenes were prepared by the melt blending of maleated polypropylenes with small diamines, including hexamethylenediamine (primary–primary diamine), p‐xylylenediamine (primary–primary diamine), and N‐hexylethylenediamine (primary–secondary diamine), at various diamine/anhydride molar ratios in a batch mixer and a twin‐screw extruder. The experimental conversion data by Fourier transform infrared nearly agreed with the assumption of a complete reaction between the primary amine and anhydride. Chain extensions of the maleated polypropylenes by the diamines were monitored by the torques during mixing and further evaluated by rheological (dynamic shear rheometry) and mechanical measurements. We show that these amino polypropylenes are very effective adhesion promoters and compatibilizers of thermoplastic polyurethanes with polypropylene. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4217–4232, 2005

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Compatibilized blends of thermoplastic polyurethane (TPU) and polypropylene (PP) were developed using amine (primary or secondary) functionalized PP's (PP‐g‐NH2 or PP‐g‐NHR). The strategy of reactive compatibilization is based on fast reactions between amine functional groups and urethane linkages or traces of free isocyanates released by thermal degradation of TPU. Excellent compatibilization between TPU and PP was confirmed by rheological, morphological, and mechanical properties. Much finer domain size, higher interfacial adhesion, and more stable morphologies were clearly observed by scanning electron microscopy. Significant improvements in the overall mechanical properties (tensile, tear, abrasion) imply significantly more reaction between TPU and PP phases in the two TPU/PP blends containing PP‐g‐NH2 or PP‐g‐NHR than a TPU/PP blend using PP‐g‐MA as a compatibilizing agent.