title: Mechanistic modeling of modular co-rotating twin-screw extruders.
abstract: In this study, we present a one-dimensional (1D) model of the metering zone of a modular, co-rotating twin-screw extruder for pharmaceutical hot melt extrusion (HME). The model accounts for filling ratio, pressure, melt temperature in screw channels and gaps, driving power, torque and the residence time distribution (RTD). It requires two empirical parameters for each screw element to be determined experimentally or numerically using computational fluid dynamics (CFD). The required Nusselt correlation for the heat transfer to the barrel was determined from experimental data. We present results for a fluid with a constant viscosity in comparison to literature data obtained from CFD simulations. Moreover, we show how to incorporate the rheology of a typical, non-Newtonian polymer melt, and present results in comparison to measurements. For both cases, we achieved excellent agreement. Furthermore, we present results for the RTD, based on experimental data from the literature, and found good agreement with simulations, in which the entire HME process was approximated with the metering model, assuming a constant viscosity for the polymer melt.
authors.affiliation: Institute for Process and Particle Engineering, Graz University of Technology, Inffeldgasse 13/III, 8010 Graz, Austria. Electronic address: andreas.eitzlmayr@tugraz.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Eitzlmayr
authors.affiliation: Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13/III, 8010 Graz, Austria. Electronic address: gerold.koscher@tugraz.at.
authors.forename: Gerold
authors.initials: G
authors.lastname: Koscher
authors.affiliation: Pharmaceutical Development, AstraZeneca, Charter Way Macclesfield, SK10 2NA, United Kingdom. Electronic address: gavin.reynolds@astrazeneca.com.
authors.forename: Gavin
authors.initials: G
authors.lastname: Reynolds
authors.affiliation: Pharmaceutical Development, AstraZeneca, Charter Way Macclesfield, SK10 2NA, United Kingdom. Electronic address: henry.huang@astrazeneca.com.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Pharmaceutical Development, AstraZeneca, Charter Way Macclesfield, SK10 2NA, United Kingdom. Electronic address: jonathan.booth@astrazeneca.com.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Booth
authors.affiliation: Pharmaceutical Development, AstraZeneca, Charter Way Macclesfield, SK10 2NA, United Kingdom. Electronic address: philip.shering@astrazeneca.com.
authors.forename: Philip
authors.initials: P
authors.lastname: Shering
authors.affiliation: Institute for Process and Particle Engineering, Graz University of Technology, Inffeldgasse 13/III, 8010 Graz, Austria; Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13/III, 8010 Graz, Austria. Electronic address: khinast@tugraz.at.
authors.forename: Johannes
authors.initials: J
authors.lastname: Khinast
mesh_terms: D002626:Chemistry, Pharmaceutical; D005615:Freezing; D006358:Hot Temperature; D011108:Polymers / Q000737:chemistry*; D012212:Rheology; D012399:Rotation; D019415:Torque; D014783:Viscosity
chemical_list: D011108:Polymers
keywords: Co-rotating twin-screw extruder; Hot melt extrusion; Non-Newtonian; One-dimensional model; Residence time distribution