A small-scale experimental extrusion set-up for exploring relationships between process-induced structures and characteristics of multiphase polymer systems

Abstract

Taking immiscible polymer blends of polystyrene (PS)/poly(methyl methacrylate) (PMMA) as a case study, we present the capabilities of a small-scale experimental extrusion set-up for sightseeing the morphological evolution during processing and identify relationships between process-induced structure, blend rheology, and product (extruded sheet) properties. In-line rheo-optical data collected with an instrumented slit die coupled to the small-scale extrusion line are in agreement with the results reported elsewhere for model polymer blends studied with simpler and slower flow fields with less relevance to industrial application. Shear stress and first normal stress difference transients relate to the stretching, orientation, break up, and subsequent string arrangement of droplets probed in the die by in-line polarized optical microscopy and small-angle light scattering. The partially relaxed droplet morphology in extruded sheets has no impact on their mechanical properties which are essentially linked to those of PS and PMMA