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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. Image 1 • The influence of shear force on the dispersed particles size for the blends was systematically investigated. • The effect of dispersed particles size and the interfacial adhesion on the impact strength of the blends was studied. • There was an optimum dispersed particle size for the best toughening effect of amorphous or highly crystalline PLA. • The suitable dispersed particles size and the appropriate interfacial adhesion are necessary for better toughening of PLA. [ABSTRACT FROM AUTHOR]

Abstract Exerting high shear force and adding compatilizer are two different methods used for regulating the size of dispersed phase of polymer blends. Nevertheless, the comparison of the effect of the high shear force and adding compatilizer on the phase morphologyies and properties is less studied, not to mention the synergistic effect. In this work, the incompatible PP/PLA binary blends with large polarity differences were prepared using high-shear processing, compared with the effect of adding ethylene-(methyl acrylate)-(glycidyl methacrylate) (EMA-GMA) as reactive compatibilizer for PP/PLA blends. It was found that adding compatilizer under relative low shear force was more efficient on improving the interface, showing blurred boundaries, compared with the reduction of the dispersed phase size under high shear force without compatilizer. As a result, the blends with the compatilizer presented a higher elongation at break; yet the yield strength of the binary blends prepared under high shear force was higher than that of the ternary blends. Furthermore, the synergistic effect of adding compatibilizer and high shear force was limited, which could be attributed to the fact that the degree of reactive compatibilization had already reached saturation under the rotation speed of 100 rpm due to the high efficiency of EMA-GMA. Graphical abstract Image 1 Highlights • The comparison of the effect of the high shear force and adding compatilizer is systematically studied. • The size of the PLA dispersed droplets decreases significantly under high rotation speed and relatively low temperature. • The PP/PLA binary blends prepared using high-shear processing show higher yield strength and lower toughness. [ABSTRACT FROM AUTHOR]