Morphology and mechanical properties of polylactide/montmorillonite composites

Abstract

In this study, polylactide (PLA)/montmorillonite (MMT) composites were prepared by melt intercalation technique. Three types of MMT, Cloisite® 30B, Cloisite® Na+ and Cloisite® Ca++DEV were used as fillers. The morphology and mechanical properties of the composite materials were investigated and compared with unfilled PLA, keeping the same thermomechanical history. The morphology of the composite materials was evaluated by small-angle x-ray scattering (SAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the tensile properties of these composites were measured by an Instron universal testing machine. The morphology observations showed that the good affinity between the organo-modified clay (Cloisite® 30B) and the PLA was sufficient to form intercalated structure in the nanocomposite. Cloisite® Na+ and Cloisite® Ca++ DEV clays exhibited a modest improvement of the young's modulus of about 18 % and 17 % respectively, due to poor dispersion in the PLA matrix as well as poor polymer-filler interactions compared to Cloisite® 30B. Compared to those of pure PLA, the PLA/Cloisite® 30B composites showed notable improvement of the Young's modulus of about 54 %.