Effect of the montmorillonite intercalant and anhydride maleic grafting on polylactic acid structure and properties

Abstract

The goal of this work is to prepare maleic anhydride grafted poly(lactic acid) (PLAgMA) according to a method described by Hwang et al. in order to investigate its effect as matrix and as compatibilizer on the dispersion of two organic nanofillers into PLA matrix, as well as its effect as compatibilizer on rheological and barrier properties of clay mineral–PLA nanocomposites. Two different montmorillonites, Cloisite® 20A and Cloisite® 30B, are used in this study. The latter is classically used in pristine PLA nanocomposites. The clay mineral polymer nanocomposites are prepared by the incorporation of 3 mass % of each layered silicate into PLA, PLAgMA and PLA/PLAgMA via melt blending. Transmission electron microscopy micrographs of the PLAgMA/Cloisite® blends showed the presence of intercalated and partially exfoliated areas with Cloisite® 20A and re-aggregation of the layered silicates with Cloisite® 30B. These results are confirmed by rheological behaviors, which showed their dependence on the content of maleic anhydride and nature of montmorillonite. Water vapor permeations (WVP) were strongly reduced by the incorporation of Cloisite®, and the better results are obtained with C20A/PLA containing 5 mass % of PLAgMA.