A novel model predicting the residence-time distribution during reactive extrusion

Abstract

A novel model predicting the residence-time distribution during reactive extrusion de Graaf, R.A.; Rohde, M.; Janssen, L.P.B.M. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract-A new model for the residence-time distribution in a counter rotating twin-screw extruder is compared with experimental results obtained during the gelatinisation of starch and the grafting of polystyrene on starch. The model consists of a transfer function from which the first three moments can be derived and is based on physical principles without any adjustable parameters. In the model and during experiments, parameters like screw rotation, fully filled length and throughput have been varied. By comparing calculated residence-time distributions with the measurements conclusions about the extruder hold-up and the fully filled extruder length can be drawn. As an extra parameter, the density change of the extruded material was needed to model the residence-time distribution curve during the grafting of polystyrene on starch. ('8 1997

A Review of Dynamic Models of Hot-Melt Extrusion

“…In the literature, a constant density is often used and the shear viscosity is modeled by an empirical equation [56][57][58] or a rheological law [35,[52][53][54][55].…”

“…In [56,57], the filling ratio, monomer concentration, temperatures and RTD are determined for a counter-rotating twin screw extruder using a subdivision of the screws in C-chambers (see Figure 10) where mass and energy balances are expressed using continuum mechanics. If the system includes a high inter-meshing area between the screws, other volume elements may be added to model the specific flows in this zone (see [52]).…”

“…In these models, pressure can be considered as a system input in completely filled zones [56,57] or can be determined by integration of the filling ratio, as in [52].…”

Scale‐Up of Extrusion‐Cooking in Single‐Screw Extruders

“…Equal residence time can be achieved if the volume divided by the throughput remains constant, or, if we define Z as the average residence time [4,8]:…”

Low-dimensional models for describing mixing effects in reactive extrusion of polypropylene

“…They showed that back pressure exists only in the presence of die component at the end of an extruder. Graaf et al (1997) derived the mathematical model that describes the residence time distribution of reactive and non-reactive system of starch extrusion in a counter rotating twin-screw extruder. The model based on the polymer moments successfully predicted the sensitivity of parameters such as screw speed, filling length of screw and throughput, on the process.…”