Interactions between PLA, organo-montmorillonite and plasticizer: Synergistic effect on the barrier and mechanical properties of PLA nanocomposites blown films

In this study, the impact of incorporating a plasticizer on the compatibility between organo-montmorillonite (OMMt) and polylactic acid (PLA) is investigated, and the resulting barrier and mechanical properties are reported. Four polymers were chosen as plasticizers to prepare the PLA nanocomposite blown films: poly(ethylene glycol), poly(ethylene oxide), polycaprolactone (PCL), and random ethylene-methyl acrylate-glycidyl methacrylate terpolymer. Firstly, 5 wt% of each plasticizer and 3 wt% of OMMt (Dellite® D43B) were mixed simultaneously with PLA in a twin-screw extruder and then introduced into the hopper of a single screw extruder to produce D43B-PLA/plasticizer nanocomposite films. The compatibilization effect was examined based on microstructure observations and thermodynamic predictions. Crystallinity was evaluated using DSC and XRD measurements. The results obtained for permeability and mechanical testing showed that the improvement of barrier and mechanical properties depends directly on the degree of compatibility between plasticizer, OMMt, and PLA. Indeed, the interfacial properties, XRD diffraction, and TEM images showed that a synergistic effect can result from high interfacial interactions between different compounds.

Mots clés

barrier properties; compatibility; mechanical properties; organo-montmorillonites; PLA; plasticizer