The combined effect of reactive and high-shear extrusion on the phase morphologies and properties of PLA/OBC/EGMA ternary blends

Abstract

Reactive extrusion and high-shear extrusion are both effective methods to regulate the size of dispersed phase and improve the properties for polymer blends, which have been investigated widely but separately. In this work, the combined effect of reactive and high-shear extrusion has been carried out in polylactide (PLA)/olefin block copolymer (OBC)/ethylenemethyl acrylate-glycidyl methacrylate terpolymer (EGMA) blends to better control the phase morphologies and improve the properties. It was found that, for PLA/OBC binary blends (80/20), the size of OBC dispersed phase decreased from 1.95 to 1.09 μm with increasing the rotation speed from 100 to 900 rpm, but the obtained phase morphologies couldn't be maintained after annealing treatment. In contrast, for PLA/EGMA binary blends (80/20), the effect of shear force on the dispersed phase size was negligible, due to the efficient reaction even under relative low shear force, and the morphologies of the annealed specimens is stable. For PLA/OBC/EGMA ternary blends, the suitable dispersed phase size and appropriate interfacial adhesion regulated by variations of composition and shear force lead to a significant increase of impact toughness. Super toughened PLA/OBC/EGMA blend (80/10/10–900) after annealing treatment shows impact strength of 49.61 kJ/m2, 21 times as comparing to that of the pure PLA. Our work demonstrates the importance of a suitable dispersed phase size and appropriate interfacial adhesion for the improvement of impact strength of PLA/OBC/EGMA blends achieved via a combined effect of reactive and high-shear extrusion.