Effect of poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and maleic anhydride-grafted SEBS triblock copolymers in immiscible blends of (polyamide-6)/polycarbonate: Morphology-mechanical properties relationships

Abstract

The effects of using maleated poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer (SEBS-g-MAH) and unmodified SEBS (unSEBS) on the phase morphology and mechanical properties of immiscible polymer blends of polyamide-6 (PA-6) and polycarbonate (PC) are investigated. Different binary, ternary, and quaternary blends were prepared by using a Brabender® co-rotating twin-screw extruder. The weight ratio of unSEBS to SEBS-g-MAH was changed to probe the phase morphology and mechanical properties. The results revealed that the mechanical properties of (PA-6)/PC/(unSEBS/SEBS-g-MAH) blends were considerably governed by the unSEBS to SEBS-g-MAH weight ratio. Morphological investigation based on the spreading coefficient concept confirmed the results of scanning electron microscopy, indicating encapsulation of unSEBS domains around the PC core-forming component in the presence of reactive SEBS-g-MAH precursor. Moreover, larger unSEBS-PC composite droplets appeared throughout PA-6 matrix upon increasing the ratio of unSEBS to SEBS-g-MAH, until reaching a maximum value. In the case of the (PA-6)/PC blend compatibilized with a 50/50 combination of unSEBS and SEBS-g-MAH, the highest mechanical properties, i.e., tensile strength, impact resistance, and strain at break, were achieved owing to compatibilizing effect of virgin and maleated SEBS constituents. J. VINYL ADDIT. TECHNOL., 21:245–252, 2015. © 2014 Society of Plastics Engineers