Modeling residence time distribution in a twin-screw extruder as a series of ideal steady-state flow reactors

Kumar, Ajay; Ganjyal, Girish M.; Jones, David D.; Hanna, Milford A.

doi:10.1016/j.jfoodeng.2007.06.017

Cited by 50 publications

(27 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For fixed screw rotating speed (shear rate) and feed rate (throughput), a shorter residence time often indicates better flow properties of the melt, which is also suggestive of lower melt viscosity (36,37). Its dependence on temperature could be easily explained using the Arrhenius equation,…”

Section: Hot-melt Extrusion Using Varying Processing Parametersmentioning

confidence: 99%

Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters

et al. 2016

View full text Add to dashboard Cite

Abstract. The aim of this article was to construct a T-ϕ phase diagram for a model drug (FD) and amorphous polymer (Eudragit® EPO) and to use this information to understand the impact of how temperature-composition coordinates influenced the final properties of the extrudate. Defining process boundaries and understanding drug solubility in polymeric carriers is of utmost importance and will help in the successful manufacture of new delivery platforms for BCS class II drugs. Physically mixed felodipine (FD)-Eudragit ® EPO (EPO) binary mixtures with pre-determined weight fractions were analysed using DSC to measure the endset of melting and glass transition temperature. Extrudates of 10 wt% FD-EPO were processed using temperatures (110°C, 126°C, 140°C and 150°C) selected from the temperaturecomposition (T-ϕ) phase diagrams and processing screw speed of 20, 100 and 200rpm. Extrudates were characterised using powder X-ray diffraction (PXRD), optical, polarised light and Raman microscopy. To ensure formation of a binary amorphous drug dispersion (ADD) at a specific composition, HME processing temperatures should at least be equal to, or exceed, the corresponding temperature value on the liquid-solid curve in a F-H T-ϕ phase diagram. If extruded between the spinodal and liquid-solid curve, the lack of thermodynamic forces to attain complete drug amorphisation may be compensated for through the use of an increased screw speed. Constructing F-H T-ϕ phase diagrams are valuable not only in the understanding drug-polymer miscibility behaviour but also in rationalising the selection of important processing parameters for HME to ensure miscibility of drug and polymer.

show abstract

Section: Hot-melt Extrusion Using Varying Processing Parametersmentioning

confidence: 99%

Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The cascade of CSTRs models the completely filled part inducing a reflux and characterized by two parameters: the number of reactors n and the ratio between the forward and backward flows σ = Q Q B . • The works in [51] and [45] suggest another model inspired by [44] for a granulation process. A plug-flow reactor is placed in series with a cascade of CSTRs with dead zones (see Figure 8) where a fraction of the material is retained.…”

Section: The Earlier Models: Static Mapsmentioning

confidence: 99%

“…To illustrate their potential, the model of [51] is used to represent the RTD measurements of Figure 3. Equation (3) is modified to include a dead zone parameter d, which influences parameter…”

Section: The Earlier Models: Static Mapsmentioning

confidence: 99%

A Review of Dynamic Models of Hot-Melt Extrusion

2016

View full text Add to dashboard Cite

Hot-melt extrusion is commonly applied for forming products, ranging from metals to plastics, rubber and clay composites. It is also increasingly used for the production of pharmaceuticals, such as granules, pellets and tablets. In this context, mathematical modeling plays an important role to determine the best process operating conditions, but also to possibly develop software sensors or controllers. The early models were essentially black-box and relied on the measurement of the residence time distribution. Current models involve mass, energy and momentum balances and consists of (partial) differential equations. This paper presents a literature review of a range of existing models. A common case study is considered to illustrate the predictive capability of the main candidate models, programmed in a simulation environment (e.g., MATLAB). Finally, a comprehensive distributed parameter model capturing the main phenomena is proposed.

show abstract

“…Residence time distribution (RTD) is an important indicator to measure the distributive mixing performance (Kumar, et al, 2008). The residence time is usually used to describe the time history of a fluid inside a reactor.…”

Section: Evaluation Of Distributive Mixing Performance With Rtdmentioning

confidence: 99%