Processing of Metallic Pigments in a Co-Rotating Twin-Screw Extruder Studied by Means of Dielectric Analysis and Terahertz Spectroscopy

When working with polymeric compounds containing metallic particles, it is essential to know the influence of the shear rate of different screw elements in a co-rotating twin-screw extruder (TSE) on particle size distribution and particle shape. Particle size and form are significant for various processing conditions. A large variety of TSE screw and mixing elements and a wide range of complex mixing geometries are available for processing polymeric compounds with metallic pigments. In this case study, we investigated the feasibility of extruding powder coatings containing metallic pigments as a replacement for the conventional bonding process. Further, we examined the influence of different screw elements on particle size by means of optical microscopy, scanning electron microscopy, dielectric analysis and terahertz spectroscopy.