Bubble-free devolatilization in counterrotating nonintermeshing twin-screw extruder

✍ Scribed by R. W. Foster; J. T. Lindt

• Publisher: Society for Plastic Engineers
• Year: 1990
• Tongue: English
• Weight: 609 KB
• Volume: 30
• Category: Article
• ISSN: 0032-3888
• DOI: 10.1002/pen.760300707

✦ Synopsis

Abstract

A theoretical analysis of the diffusion‐controlled, essentially bubble‐free, mass transfer regime of polymer solution devolatilization has been performed for a counterrotating, nonintermeshing twin‐screw extruder (1). The commonly used penetration diffusion approach is applied specifically to this geometry. Mass transfer from the recirculating pool and barrel film in the closed channel and the pool only in the open channel is taken into account. Use is made in this study of the recently determined pumping characteristics of this geometry (2), which allow the estimation of the length of the extraction section. Mass transfer rate measurements have been taken on a 20‐mm extruder using the model system polystyrene/ethylbenzene. The agreement between the mass transfer calculations and the experimental results is very good.