Abstract: Polypropylene (PP)/nano-CaCO3/profiled fibers composites were prepared via melt blending. The profiled fibers had cylindrical, flat, or triangular cross-sections. The structure of untreated and treated CaCO3 was investigated and the dispersion condition was observed by means of SEM. It showed that silane coupling agent was better than stearic acid. Fibers with different cross-sections have different influence on the mechanical properties. The composite containing triangular fiber with the largest surface area was much better than others. When the mass fraction of nano-CaCO3 was 3 % (silane coupling agent was 2 %) and the volume fraction of triangular fibers was 2 % (coupling agent was 4 %)，length/diameter(L/D) was 80, the yield strength and elastic modulus of the composites were increased by 21 % and 82 %, respectively.

Key words: calcium carbonate, profiled fiber, composite, polypropylene, coupling agent, polyethylene terephthalate, mechanical property