Poly(lactic acid) nanocomposites with various organoclays. I. Thermomechanical properties, morphology, and gas permeability

The thermomechanical properties, morphology, and gas permeability of hybrids prepared with three types of organoclays were compared in detail. Hexadecylamine-montmorillonite (C-16-MMT), dodecyltrimethyl ammonium bromide-montmorillonite (DTA-MMT), and Cloisite 25A were used as organoclays in the preparation of nanocomposites. From morphological studies using transmission electron microscopy, most clay layers were found to be dispersed homogeneously in the matrix polymer, although some clusters or agglomerated particles were also detected. The initial degradation temperature (at a 2% weight loss) of the poly(lactic acid) (PLA) hybrid films with C-16-MMT and Cloisite 25A decreased linearly with an increasing amount of organoclay. For hybrid films, the tensile properties initially increased but then decreased with the introduction of more of the inorganic phase. The O-2 permeability values for all the hybrids for clay loadings up to 10 wt % were less than half the corresponding values for pure PLA, regardless of the organoclay. (C) 2002 Wiley Periodicals, Inc.