Binary blends using metallocene ethylene-1-octene copolymer as matrix were prepared and subjected to electron beam (EB)irradiation (50, 100, and 200 kGy). Gel content and melt flow index values indicated that the blends were crosslinking. Fourier transform infrared-ATR spectroscopy was used to study the crosslinking and oxidative degradation of the blends via tertiary carbon and carboxyl group formation, respectively. Thermal and mechanical properties were studied showing that the crystallinity of both matrix and dispersed phase decreased with irradiation dose, and that the thermoplastic elastomers with good mechanical properties may be obtained by EB irradiation. Chain branching and scission were also detected at all irradiation doses, although at the highest doses (200 kGy) a crosslinking reaction was the most predominantly observed effect. The successive self-nucleation annealing technique was used to determine the EB irradiation effects on crystallization of some blends in which crosslinking and chain branching take place, modifying the chain's structure and therefore crystalline regions in the matrix and the dispersed phase. (c) 2007 Wiley Periodicals, Inc.