A modified clay was used to prepare poly(L-lactic acid)/clay nanocomposite dispersions. X-ray diffraction and transmission electron microscopy experiments revealed that poly(L-lactic acid) was able to intercalate the clay galleries. IR spectra of the poly(L-lactic acid)/ clay nanocomposites showed the presence of interactions between the exfoliated clay platelets and the poly(L-lactic acid). Thermogravimetric analysis and differential scanning calorimetry were performed to study the thermal behavior of the prepared composites. The properties of the poly(L-lactic acid)/clay nanocomposites were also examined as functions of the organoclay content. The exfoliated organoclay layers acted as nucleating agents, and as the organoclay content increased, the crystallization temperature increased. (c) 2007 Wiley Periodicals, Inc.