Concepts responsible for creating properties on co-rotating twin screw extruders Degree-of-fill, shear rate, residence time, heat transfer Dispersive vs. distributive mixing Influence of extruder configuration on compounding performance How machine design impacts mixing (e.g. d0/di, co vs counter, etc.) What is optimum extruder configuration?
Description of unit operations: feeding, melting, mixing, venting, pressurization Introduction of the process model – role of specific energy Interaction of process parameters Process optimization
The “Art” of Screw Design
Working principles for each element type (conveying, mixing) Overview of available screw element designs Characterization of dispersive and distributive mixing elements Selection of the optimum screw type for each of the unit operations Examination and analysis of typical compounding screw configurations Masterbatch, concentrates Non-reinforcing fillers Fiber compounding Liquid additives
Scale-up factors based on volume, power, and heat transfer
Process Troubleshooting Diagnosis of compounding instabilities with respect to residence time Consistency (i.e. within-lot) Reproducibility (i.e. lot-to-lot)