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.
Poly(vinyl alcohol) (PVA)/clay nanocomposites were synthesized using the solution intercalation method. Na ion-exchanged clays [Na ϩ -saponite (SPT) and Na ϩ -montmorillonite (MMT)] and alkyl ammonium ionexchanged clays (C 12 -MMT and C 12 OOH-MMT) were used for the PVA nanocomposites. From the morphological studies, the Na ion-exchanged clay is more easily dispersed in a PVA matrix than is the alkyl ammonium ion-exchanged clay. Attempts were also made to improve both the thermal stabilities and the tensile properties of PVA/clay nanocomposite films, and it was found that the addition of only a small amount of clay was sufficient for that purpose. Both the ultimate tensile strength and the initial modulus for the nanocomposites increased gradually with clay loading up to 8 wt %. In C 12 OOH-MMT, the maximum enhancement of the ultimate tensile strength and the initial modulus for the nanocomposites was observed for blends containing 6 wt % organoclay. Na ion-exchanged clays have higher tensile strengths than those of organic alkyl-exchanged clays in PVA nanocomposites films. On the other hand, organic alkyl-exchanged clays have initial moduli that are better than those of Na ion-exchanged clays. Overall, the content of clay particles in the polymer matrix affect both the thermal stability and the tensile properties of the polymer/clay nanocomposites. However, a change in thermal stability with clay was not significant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.