In-line particle size assessment of polymer suspensions during processing

Abstract

The validation and the operating window of an in-line rheo-optical slit die coupled to a prototype single/twin-screw mini-extrusion system are reported. This experimental set-up is able to perform in-situ rheological measurements, together with Small Angle Light Scattering (SALS) and Polarized Optical Microscopy (POM), thus enabling the structural characterization of materials during extrusion. The optical validation focuses on particle sizing and is performed using standard size particles suspended in a Newtonian polydimethylsiloxane (PDMS) matrix. The outcome is a map of the range of particle sizes and concentrations that can be measured with the two complementary in-line optical techniques. The techniques are then applied to study the morphological development in PMMA/PS blends, in order to screen for their applicability to commercial systems. Thus, limitations of POM and SALS for the characterization of industrial materials are also indicated.