One-Step Reactive Branching for Compatibilization of PA6/PA66 Blends: Achieving Concurrent Improvements in Mechanical Properties, Foamability, and Creep Resistance

Abstract A simple one-step branching approach was employed to achieve simultaneous enhancement of compatibility, strength, toughness, viscoelasticity, and dimensional stability of PA6/PA66 blends through reactive extrusion. The occurrence of branching reactions and the presence of branched structures were confirmed by torque rheometer, FTIR, GPC, and rheological analysis. A selective foaming approach was adopted to investigate the effects of the modifier ADR on phase size and interfacial adhesion. The correlation between branched architecture and the mechanical properties, foamability, and creep resistance of PA6/PA66 blends was further investigated in detail. The results demonstrated that, compared to the unmodified PA6/PA66 blends, incorporation of 5.0 wt % ADR reduced the PA66 phase size from 28.0 to 7.9 μm, consequently increasing the tensile strength and tensile toughness by 18.4% and 390.6%, respectively. Furthermore, the branched structures introduced by ADR significantly enhanced both the foaming performance and dimensional stability of the blends, substantially broadening the foaming temperature window (35 °C), increasing the expansion ratio (18.2-fold), and reducing the creep strain. The branched PA6/PA66 blends also retained the toughness of branched PA6 as well as the strength and creep resistance of branched PA66. This work provides important insights for the controlled preparation and property optimization of multifunctional PA-based blends.