Devolatilization via Twin-Screw ExtrusionTheory, Tips, and Test Results
In a twin-screw extruder (TSE), the mixing/blending of polymers/additives and devolatilization are mass-transfer operations dependent upon shear/energy that is being imparted into the materials being processed by rotating screws. In pharmaceutical applications, devolatilization (DV) could refer to the removal of residual solvents from an active pharmaceutical ingredient (API), removal of water from the process that could cause degradation through hydrolysis, or even simply removing air to reduce entrapped bubbles in the final product. Process control parameters include screw speed (rpm), feed rate, barrel/die temperatures, and vacuum level. Twin-screw extrusion continues to evolve and become more integrated in the pharmaceutical industry in research, development, and manufacturing. However, while extrusion applications and techniques have risen to the forefront, devolatilization is currently underutilized in pharmaceutical installations. Nevertheless, as understanding of the technology and realization of its importance becomes apparent, devolatilization will become more commonplace.