Epoxidized natural rubber (ENR) with a level of epoxide groups of 20 mol % was prepared via the performic epoxidation method. It was then used to blend with high-density polyethylene (HDPE) at various blend ratios. Three types of blend compatibilizers were prepared. These included a graft copolymer of HDPE and maleic anhydride (MA; i.e., HDPE-g-MA) and two types of phenolic modified HDPEs using phenolic resins SP-1045 and HRJ10518 (i.e., PhSP-PE and PhHRJ-PE), respectively. We found that the blend with compatibilizer exhibited superior tensile strength, hardness, and set properties to that of the blend without compatibilizer. The ENR and HDPF interaction via the link of compatibilizer molecules was the polar functional groups of the compatibilizer with the oxirane groups in the ENR molecules. Also, another end of the compatibilizer molecules (i.e., HDPE segments) was compatibilizing with the HDPE molecules in the blend components. The blend with compatibilizer also showed smaller phase morphology than the blend without compatibilizer. Among the three types of the blend compatibilizer, HDPE-g-MA provided the blend with the greatest strength and hardness properties but the lowest set properties. (c) 2008 Wiley Periodicals, Inc.