Effect of mixing protocol on the morphology development of multi-walled carbon nanotubes incorporated ternary blends of polycarbonate, styrene-acrylonitrile, and poly(methyl methacrylate) in a twin screw extruder

摘要

In this study, the effects of component pair miscibility and mixing sequence on the phase structure of ternary blends of polycarbonate (PC), styrene-acrylonitrile (SAN), and poly(methyl methacrylate) (PMMA), and their composites with multi-walled carbon nanotubes (MWCNTs) were investigated. SAN phase was surrounded by a layer of PMMA in the PC matrix and the thickness of the shell was dependent on the content of acrylonitrile (AN) in SAN (24% vs. 32%). It was established that the miscibility between SAN and PMMA affects the shell thickness on the merging of SAN and PMMA domains, which were separately dispersed at the early stage of kneading section in a twin-screw extruder. Consequently, the PMMA shell around the SAN was thinner in the SAN24, which is miscible with PMMA. When the pre-compounded composites of SAN/PMMA/MWCNT were mixed with PC through a 2-step blending, shell formation was promoted only with SAN32, which is immiscible with PMMA at a processing temperature. Additionally, it was established during the 2-step blending that the MWCNTs pre-dispersed in SAN and PMMA were transferred to the PC phase. This migration behavior of MWCNTs was prevented by introducing viscous impact modifiers. The change in electrical resistivity of the composites was explained using the observed phase morphology.