The use of nanoparticulates in polymeric materials has become a potential alternative for organic-inorganic composite materials because of their versatility in property modification and ease of batch fabrication. This paper investigates the kneading and mechanical properties of polypropylene (PP) with added nano-ZnO powder in sizes of 10-30 nm, through batch kneading and microinjection molding processes. The results show that the PP microgears with added ZnO nanoparticles are well replicated with clear structural definition. The resulting composites with a small amount of nanofiller added exhibit significant improvement in wear resistance and mechanical properties. The possible strengthening and wearing mechanisms is discussed based on the investigation of the worn and fractured surfaces of the composites. (c) 2006 Wiley Periodicals, Inc.