In-line rheo-optical characterisation of polymeric systems

Abstract

As increasingly more sophisticated polymer systems are being developed, it is important to rapidly estimate their processability, morphology after processing and performance under service conditions, if possible using small amounts of materials. In order to accomplish this, a single I twin-screw mini-extrusion system of modular construction, with well-controlled outputs in the range 30-300 g/h, was coupled to a rheological slit die able to measure shear viscosity and normal-stress differences, as well as performing rheo-optical experiments, namely small angle light scattering (SALS) and polarized optical microscopy. In addition, the extrudate can be directly used for mechanical testing. The first normal stress difference is determined using the hole pressure method. Low and high volume fraction -dispersions of standard size particles in polydimethylsiloxane are used to map the potential of the technique for assessing in-line the size and structural arrangements of fillers in polymer melts. Application of the in-line rheo-optical characterization to a model polymer blend is also presented.