The Selective Localization of Organic Montmorillonite at the Interface and Its Effects on the Micro-Morphology and Properties of Bio-Based Polylactic Acid/Eucommia Ulmoides Gum (PLA/EUG) Blends

Highly toughened bio-based polylactic acid (PLA)/<i>Eucommia ulmoides</i> gum (EUG) blends were prepared using organic montmorillonite (OMMT) as a compatibilizer through melt-blending. Both the theoretically predicted values and the experimental results confirm that the majority of the OMMT's nanolayers are selectively localized at the PLA/EUG interface. This localization leads to improved interfacial properties and a more refined morphology of the dispersed EUG phase. By increasing the OMMT content from 0 phr to 2 phr, the notched Izod impact strength of the PLA/EUG/OMMT (85/15/2) blend increases to a maximum value of 44.6 kJ/m². This is significantly higher than the values observed for neat PLA at 3.8 kJ/m² and the PLA/EUG (85/15) blend at 4.7 kJ/m². Moreover, compared to neat PLA and the PLA/EUG (85/15) blend, which exhibit poor tensile ductility, as indicated by their low elongation at break, the PLA/EUG/OMMT blend demonstrates a substantial improvement in its tensile ductility when an appropriate amount of OMMT is added. It is believed that the enhanced toughness of the PLA/EUG/OMMT blends can primarily be attributed to the refinement and more uniform dispersion of the EUG domains, which is caused by the incorporation of OMMT. In addition, the crystalline properties, thermal degradation behavior, and extrudate swell behavior of the PLA/EUG blends with and without OMMT were also evaluated in detail. Finally, the experimental results prove that the PLA/EUG (85/15) blend containing 2 phr of OMMT exhibits the highest impact toughness and tensile ductility, accompanied by improved thermal stability and extrusion stability.