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Title: DEM-PBM modelling of pharmaceutical ribbon breakage
Author: Loreti, Simone
ISNI:       0000 0004 6501 012X
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2018
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Milling of roll compacted ribbons is a commonly used unit operation in the pharmaceutical industry to improve the manufacturability of fine powders. In this thesis, two computational techniques, the Discrete Element Method (DEM) and the Population Balance Modelling (PBM), are combined into a coupled DEM-PBM framework, to investigate the micro-mechanics of ribbon breakage in milling. The effects of interfacial energy and porosity on the mechanical properties of ribbons and the effects of interfacial energy, impact velocity and abrasion velocity on ribbon fragmentation during impact and abrasion tests are explored. On the effects of interfacial energy and porosity on the mechanical properties of ribbons, it is found that the tensile strength of the ribbon is a linear function of the interfacial energy and an exponential function of the porosity. An equation to evaluate the ribbon’s tensile strength, from both the porosity and the interfacial energy is then derived. The proposed equation, which is similar to the Ryshkewitch-Duckworth (RD) formula that considers only the porosity, can be considered as an extension of the RD equation to consider the interfacial energy effect. On the impact and abrasion tests, mathematical models are derived to describe the dependency of the number of large fragments and the fraction of fines (small fragments), resulting in DEM ribbon impact and abrasion tests on the interfacial energy, the impact velocity and the abrasion velocity. It is found that these models, when used as input for PBM, in a multiscale DEM-PBM modelling framework, reasonably well predict the experimental data for the impact tests and are in good agreement with the experimental data for the abrasion tests.
Supervisor: Wu, Chuan-Yu (Charley) Sponsor: IPROCOM Marie Curie Initial Training Network
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available