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On the physical interpretation of the Kawakita and Adams parameters derived from confined compression of granular solids
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2008 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 182, no 3, 424-435 p.Article in journal (Refereed) Published
Description
Abstract [en]

The objective of this paper was to investigate the physical significance of the Kawakita and Adams parameters derived from the compressionof some granular solids. Four model granules of different expected deformation behaviour were prepared by varying the composition and porosityof the granules. The granules were nearly spherical and of similar size and showed a variation in mechanical properties in terms of their elasticity,plasticity, fracture strength and brittleness. Due to the size and shape of the granules, compression due to granule rearrangement was generallylimited. The Kawakita a parameter approximated the maximal engineering strain of the granular solids and both the Kawakita a and b−1parameter reflected the plasticity of the granules. The Adams parameter τ0 seemed to reflect the initial cracking of granules. Thus, the combineduse of the Kawakita parameters a and b−1 and the Adams parameter τ0 may give a comprehensive representation of the compression behaviour ofgranular solids.

Place, publisher, year, edition, pages
2008. Vol. 182, no 3, 424-435 p.
Keyword [en]
Compression, powder, granular materials, compression parameters, Kawakita, mechanical properties
National Category
Pharmaceutical Sciences Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-97466DOI: 10.1016/j.powtec.2007.07.009ISI: 000254818800012OAI: oai:DiVA.org:uu-97466DiVA: diva2:172427
Available from: 2008-09-09 Created: 2008-09-09 Last updated: 2016-05-13Bibliographically approved
In thesis
1. Compression analysis as a tool for technical characterization and classification of pharmaceutical powders
Open this publication in new window or tab >>Compression analysis as a tool for technical characterization and classification of pharmaceutical powders
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There are today strong incentives for an increased understanding of material properties and manufacturing processes to facilitate the development of new technologies in the pharmaceutical industry. The purpose of this thesis was to suggest methods requiring a low sample amount for characterization of technical properties of powders.

Compression analysis was used to evaluate the formulation relevance of some compression equations. Using the mechanics of single granules to estimate powder functionality was part of this work. It was concluded that the formability of granular solids and the plasticity of single granules could be determined with compression analysis by using the Kawakita model for single components and binary mixtures of ductile granules.

Further on, the fragmentation propensity of solid particles could be estimated from compression analysis by using the Shapiro equation, enabling indicators of both the fragmentation and the deformation propensity of particles to be derived in one single compression test.

The interpretations of the compression parameters were only valid if the influence of particle rearrangement was negligible for the overall compression profile. An index indicating the extent of particle rearrangement was developed and a classification system of powders into groups dependent on the incidence of particle rearrangement was suggested as tools to enable rational interpretations of compression parameters.

The application of compression analysis was demonstrated by investigating the relevance of the mechanics of granular solids for their tableting abilities. The plasticity of single gran-ules was suggested to influence both the rate of compactibility and the mode of deformation, and consequently the maximal tablet strength. The degree of granule bed deformation was shown to be a potential in line process indicator to describe the tableting forming ability.

This thesis contributes to a scheme, suitable in formulation work and process control, to describe manufacturability of powders for an enhanced tablet formulation technology.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 72 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 79
Keyword
compaction, compression, granules, Kawakita, mechanical properties, particles, PAT, pharmaceutical powders, tablets
National Category
Pharmaceutical Sciences
Identifiers
urn:nbn:se:uu:diva-9214 (URN)978-91-554-7265-8 (ISBN)
Public defence
2008-10-03, B21, Biomedical Center, BMC, Husargatan 3, Uppsala, 13:15
Opponent
Supervisors
Available from: 2008-09-09 Created: 2008-09-09Bibliographically approved

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Welch, KenFrenning, Göran

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