Poly(lactic acid) (PLA) nanocomposites containing five types of organically modified, layered silicates and two elastomeric compatibilizers, namely ethylene-glycidyl methacrylate (E-GMA) and ethylene-butyl acrylate-maleic anhydride (E-BA-MAH), were prepared using a twin screw extruder. The morphologies of the nanocomposites were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the rheological properties of the melts were measured using small-amplitude oscillatory shear. XRD revealed that the addition of E-GMA to the binary nanocomposites resulted in higher compatibility between the organoclay nanoplatelets and the polymer matrix. TEM showed that all of the nanocomposites contained mixed dispersed structures, involving tactoids of various sizes, as well as intercalated and exfoliated organoclay layers. Rheological properties were found to be affected by the differences in the compatibility between the organoclays and the polymer matrix, and by the addition of the compatibilizer. Organoclay types that resulted in high level of dispersion exhibited higher values of complex viscosity compared to that of neat PLA. The addition of E-GMA introduced a solid-like rheological behavior at low frequencies. All of the nanocomposites had similar rheological behavior at high frequencies. (C) 2015 Wiley Periodicals, Inc.