Composites of poly(lactic acid) (PLA) and organoclays with clay loadings of up to 80% were prepared as self-supporting films using a doctor-blading approach. Depending on the properties of the used organoclay, either intercalated nanocomposites or conventional composites were obtained. The incorporation of such high amounts of clay resulted in up to 10-fold decrease in the water vapor transmission rate when compared to the pristine polymer. The effect of clay platelets on the crystallization of PLA chains was also studied; it was found that high amounts of clay hinder only the melt crystallization of the polymer, whereas cold crystallization proceeds as usual. On the other hand, the crystallization of PLA also influenced the composite structure by increasing the extent of intercalation of polymer between clay layers. This study thus shows that the change in the extent of clay-polymer interactions is also an important factor in controlling nanocomposite structure, especially for high loading. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013