A solid-state mechanochemical pulverization process, that is, pan milling, was used to prepare a polypropylene (PP)/carbon nanotube (CNT) composite powder. The composite powder was then melt-mixed with a twin-roll masticator to obtain a PP/CNT composite. The morphology of the PP/CNT powder and the PP/CNT composite was investigated. The crystallization and mechanical properties of the latter were also studied. After 20 milling cycles (ca. 60 min), the average diameter of PP/3 wt % CNT composite powder particles was a few micrometers. The length of the CNTs was reduced from a few micrometers to 0.4-0.5 mum. The CNTs became straighter and more uniform in length. The effects of incorporating the CNTs into PP were as follows: (1) the crystallization rate and temperature of PP increased, (2) a strong b-plane orientation of PP was induced, and (3) the Young's modulus and yield strength of PP increased. Interfacial adhesion between PP and the CNTs was improved by the mechanical action of the solid-state pulverization process used, which favored the dispersion of the CNTs into PP. (C) 2004 Wiley Periodicals, Inc.