The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene-co-vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes-melting, transitions, and reactions-all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry. (c) 2006 Wiley Periodicals, Inc.