Characterization of kneading block performance in co-rotating twin screw extruders

This is a first part of a series of papers focusing solely on kneading block performance. Direct measurements of dye intensity, fill length and residence time were conducted to quantify mixing. Image analysis and visualization were performed in a 30 mm TSE with transparent barrel to investigate the flow behavior and mixing performance of narrow kneading blocks. Narrow kneading blocks were found to display a relatively wide dye intensity distribution at low percent drag flow, which implies an intense mixing in axial direction. The distribution becomes narrow with increasing percent drag flow. The fill length and residence times in the kneading blocks are functions of percent drag now. There is a turning point for fill length at 30% drag flow. Viscoelastic materials show longer fill length and residence time in comparison to Newtonian fluids.