AbstractThe current investigation was aimed at assessing the effect of carboxylation of NBR phase in dynamically vulcanized NBR/low‐melting polyamide thermoplastic elastomeric compositions. Improved strength and set properties were achieved because of better compatibilization with carboxylated NBRs. The dispersion of the rubber became homogeneous and finer with increase in the degree of carboxylation. Glass transition studies by DMA and DSC suggested the presence of a compatibilizing block copolymer generated in situ by the reaction between the COOH groups in the rubber and the NH2 groups in the polyamide during melt‐mixing. The reaction was studied for a representative 60 : 40 rubber/plastic blend by DSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1008–1012, 2006