It is well known that PLA crystallizes slowly compared with other polyesters such as PCL and polyethylene terephthalate because of the rigid segments in its main chain.17 In Figure 4 we can see that, at the cooling rate of 10 °C/min, the pure PLA does not crystallize, therefore no crystallization peak is visible in its cooling thermogram. This result implies that the pure PLA samples cooled from the isotropic melt at a cooling rate more than 10 °C/min remain amorphous. However, for 2 and 5 wt % 30B nanocomposites, crystallization peaks of PLA were observed with the peak temperatures around 90 °C. These results clearly show that small amounts of 30B exfoliated in PLA matrix result in an obvious increase of the crystallization rate as compared with the pure PLA. This behavior can be explained by the assumption that the exfoliated silicate layers act as efficient nucleating agents, which enhance the crystallization rate of the matrix molecules, and this effect will be increased with the increasing of the organoclay contents because of the increased amount of nucleating agents.