Intercalative polymerization of L-lactide with organically modified clay by a reactive extrusion method and instrumental analyses of the poly(lactic acid)/clay nanocomposites

Using a reactive extrusion-molding process, we produced poly(lactic acid) (PLA) nanocomposites from L-lactide monomer in the presence of organic montmorillonites. On the basis of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses, we determined that the intercalation of the PLA between the clay layers in the mixing process, followed by disappearance of agglomeration, proceeded in the extrusion process. Although only a slight change in the chemical shifts in cross-polarization/magic angle spinning 13C-NMR was observed with the addition of the organic clay, the presence of the additive and the organic content of the nanocomposites affected the nuclear magnetic relaxation times [the 1H spin-lattice relaxation time (T1H) and the 13C spin-lattice relaxation time (T1C)] for different temperatures. The nanoclay suppressed increases in T1H at elevated temperatures and extended T1C values of C=O and CH around room temperature. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012