Super toughened immiscible polycarbonate/poly(l-lactide) blend achieved by simultaneous addition of compatibilizer and carbon nanotubes

Abstract

Polycarbonate/poly(L-lactide) (PC/PLLA) blend exhibits great potential application in several fields, including package, toy, electronic element and automobile. However, the poor mechanical properties of the immiscible PC/PLLA blend restrict its application. In this work, a compatibilizer maleic anhydride grafted ethylene–octene copolymer (EOR-g-MAH) and functionalized carbon nanotubes (F-CNTs) were introduced into the immiscible PC/PLLA blend by simple melt-compounding processing. Mechanical property measurements showed that even at low environmental temperature (0 °C), the blend composites exhibited excellent fracture toughness, e.g. 40.9 ± 2.1 kJ m⁻² at F-CNT content of 2 wt%. To better understand the toughening mechanism, the morphologies of the blend composites and the dispersion of F-CNTs and the rheological properties were systematically investigated. The results showed that with the combined effects of EOR-g-MAH and F-CNTs, the decreased PLLA particles were achieved. Most of F-CNTs selectively located in the PC matrix and some F-CNTs entered into PLLA particles. Specifically, at relatively high content (>2 wt%), F-CNTs formed percolated network structure. Then, the toughening mechanism was proposed on the basis of the morphology evolution, the formation of F-CNT network structure and the impact-fractured surface morphologies. This work demonstrated that even for the immiscible polymer blend, the super toughened blend composites could be achieved by the combined effects of compatibilizer and carbon nanotubes, and therefore it provides an alternative strategy for largely improving the fracture toughness of immiscible polymer blends.