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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]

Melt mixing and solution mixing are two commonly used methods for the preparation of polymer nanocomposites. In this work, thermoplastic polyurethane (TPU) composites with unmodified MWCNTs and carboxyl MWCNTs (MWCNT-COOH) were prepared using melt mixing and solution mixing. The dispersion of filler in TPU matrix and the macro-properties of composites under different processing conditions were systematically investigated. It was found that for pristine MWCNTs, a better dispersion was obtained using solution method at relatively low content of fillers (≤2.5 wt%); but when the content of MWCNT was above 2.5 wt%, melt mixing under high shear force was more effective to achieve a homogeneous dispersion. The similar result was confirmed in TPU/MWCNT-COOH composites, with the critical concentration shifted to 5.0 wt%, indicating that the interaction between CNT and TPU also played role on the dispersion of CNT in TPU matrix via solution mixing. Our finding is important for the preparation of polymer/CNT nanocomposites with good dispersion depending on the filler content and mixing methods. Image 1052 • The dispersion state of CNT in TPU matrix with solution and melt mixing was compared. • The effect of the concentration and the surface modification of CNT on the dispersion of CNT in TPU matrix was studied. • Melt mixing under high shear force with unmodified MWCNTs is a better way to obtain high-performance composites. [ABSTRACT FROM AUTHOR]