Turner, TD orcid.org/0000-0003-3776-2044, Gajjar, P, Fragkopoulos, IS et al. (7 more authors) (2020) Measuring the Particle Packing of l-Glutamic Acid Crystals through X-ray Computed Tomography for Understanding Powder Flow and Consolidation Behavior. Crystal Growth & Design, 20 (7). acs.cgd.9b. pp. 4252-4263. ISSN 1528-7483
Abstract
The morphology of free-flowed and gravity consolidated crystal powder beds of the alpha and beta polymorphic forms of l-glutamic acid, together with a detailed analysis of particle density and microstructure within alpha form tablets using state -of-the-art X-ray computed tomography (XCT), is presented. The Carr’s index is measured to be 19.7 and 35.2 for the bulk powders of the prismatic alpha form and needle-like beta form, respectively, revealing the alpha forms increased powder flowability versus the beta form. XCT reveals the alpha form consolidates under gravity more efficiently than beta, where the final measured bed density of the alpha form is 0.724 g/cm3 compared to 0.248 g/cm3 for the beta form, which is found to be caused by the inability of the beta particles to pack efficiently along their needle axis. Tabletting studies reveal that the alpha form consolidates into compacts of intermediate tensile strength, whereas the beta form cannot be compacted under these conditions. XCT analysis of tablets formed from α-form crystals reveals two discrete density regimes, one low-density region of fine powder which accounts for 53.8% of the compact, and high-density regions of largely intact single crystals which account for 44.2% of the compact. Further analysis of the tablet microstructure reveals that the crystal particles are generally orientated with their basal {0 0 1} plane, normal to the compaction force and that small microcracks which appear within the particles generally occur perpendicular to the surface and are orientated through possible {1 1 0} and {1 0 1} fracture planes. XCT also reveals evidence for incipient transformation between the meta-stable alpha to stable beta phase at concentrations below that detected using laboratory X-ray diffraction. The results show that XCT can accurately measure the extent of tapping induced densification and reveals the powder bed mesostructure characteristics and tablet microstructure for the two polymorphic forms of alpha and beta l-glutamic acid.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium,provided the author and source are cited. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Inorganic Chemistry (Leeds) |
Funding Information: | Funder Grant number EPSRC (Engineering and Physical Sciences Research Council) EP/I028293/1 Innovate UK fka Technology Strategy Board (TSB) 14060 EPSRC (Engineering and Physical Sciences Research Council) EP/N025075/1 EPSRC (Engineering and Physical Sciences Research Council) EP/R00661X/1 EPSRC (Engineering and Physical Sciences Research Council) EP/N025075/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 29 May 2020 15:24 |
Last Modified: | 25 Jun 2023 22:17 |
Status: | Published |
Publisher: | American Chemical Society (ACS) |
Identification Number: | 10.1021/acs.cgd.9b01515 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:161279 |