Ternary composites of high-density polyethylene (HDPE)/maleated poly(ethylene-octene) (POE-g)/calcium carbonate (CaCO3) were prepared by the melt extrusion process. Crystallization behavior investigation and mechanical properties study showed that there existed a transition in both crystallization temperature (T-c) and impact strength of ternary composites. These transitions were attributed to the development of morphology, with variation of concentration of POE-g in ternary composites. The strength of interfacial adhesion also influenced the property transitions. (c) 2006 Wiley Periodicals, Inc.