A thermoplastic resin based on ethylene/ methacrylic acid copolymer (EMA) was used as a modifier for different low density polyethylene (LDPE) batches under the effect of electron beam irradiation. The EMA resin was used in the zinc metal form at a constant ratio of 9 wt% in all preparations. The effect of EMA resin as a crosslinking agent was characterized by percentage gel fraction, tensile mechanical, and differential scanning calorimetry (DSC). In this study, the maximum gel content (G(max)) and gelling dose (D-gel) parameters were determined by applying the familiar Charlesby-Pinner relationship. The results showed that the gel content for all investigated samples gradually increases with increasing irradiation dose. The modified LDPE batches with EMA show higher gel content than unmodified ones at any irradiation dose. Also, the gel content of all LDPE composites decreases as a result of post-storage effect. The mechanical properties (tensile strength and elongation at break) exhibit significant change as a result of irradiation and blending the LDPE batch with EMA. The level of change in mechanical properties seems to be more pronounced for EMA-modified LDPE batches. © 2005 Wiley Periodicals, Inc.