Dynamic vulcanization was studied in terms of the change in alpha-relaxation temperatures of the LDPE matrix, morphology, and mechanical properties of LDPE/ozonolysed NR blends which were vulcanized at various blend ratios and with different curing systems, i.e., peroxide and sulfur systems. The ozonolysed NR with (M) over bar (w) 8.30 x 10(5) g mol(-1) and (M) over bar (n) 2.62 x 10(5) g mol(-1), prepared by the in situ ozonolysis reaction of natural rubber latex, was used in this study. The significant change in the a-relaxation temperature of LDPE in the LDPE/ozonolysed NR, dynamically vulcanized using the sulfur system, suggested that sulfur vulcanization of the blend gave a higher degree of crosslink density than using peroxide and corresponded with the improved damping property and homogenous phase morphology. However, the peroxide cured blends of LDPE/ozonolyzed NR gave more improvement of tensile strength and elongation at break than the sulfur cured system. Furthermore, the mechanical properties of tensile strength, elongation at break, and damping were improved by increasing the ozonolyzed natural rubber content in both DCP and sulfur cured blends. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2606-2614, 2011