Density and plastic strain evaluations using small-angle X-ray scattering and finite element simulations for powder compacts of complex shape

Han, Lianghao; Laity, Peter R.; Cameron, Ruth E.; Elliott, James A.

doi:10.1007/s10853-011-5559-8

Cited by 13 publications

(17 citation statements)

References 38 publications

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“…Hence, the results obtained here for gMgSm agreed reasonably well with previously published results for compacted clays [Vanorio et al 2003, Mondol et al2007, Moyano et al 2012 and were somewhat larger than expected for sMCC, based on data previously reported by Han et al [2011]. The smaller modulus of sMCC suggests that it should exhibit greater strain during loading and unloading than gMgSm, which is counter to the observations.…”

Section: Bulk Compaction Behavioursupporting

confidence: 92%

“…Significant differences can be observed between flat-faced and convex punches, while dramatic effects can be produced by embossed features [Sinka et al 2004, Djemai and Sinka 2006, Wu et al 2008, McDonald et al 2009, Han et al 2011, Laity 2014. The density variations can also be affected by the compaction method; friction against the die walls during single-ended compaction causes distinct asymmetry between the static and driven faces, while double-ended compaction (i.e.…”

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confidence: 99%

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Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Laity

Asare-Addo

Sweeney

et al. 2015

Applied Clay Science

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ABSTRACT:The compaction behaviour of a commercial granulated clay (magnesium aluminium smectite, gMgSm) was investigated using macroscopic pressure-density measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray microtomography (XµT) and small-angle X-ray scattering (SAXS). This material was studied as a potential compaction excipient for pharmaceutical tabletting, but also as a model system demonstrating the capabilities of SAXS for investigating compaction in other situations.Bulk compaction measurements showed that the gMgSm was more difficult to compact than polymeric pharmaceutical excipients such as spheronised microcrystalline cellulose (sMCC), corresponding to harder granules. Moreover, in spite of using lubrication (magnesium stearate) on the tooling surfaces, rather high ejection forces were observed, which may cause problems during commercial tabletting, requiring further amelioration. Although the compacted gMgSm specimens were more porous, however, they still exhibited acceptable cohesive strengths, comparable to sMCC. Hence, there may be scope for using granular clay as one component of a tabletting formulation.Following principles established in previous work, SAXS revealed information concerning the intragranular structure of the gMgSm and its response to compaction. The results showed that little compression of the intragranular morphology occurred below a relative density of 0·6, suggesting that granule rearrangements or fragmentation were the dominant mechanisms during this stage. By contrast, granule deformation became considerably more important at higher relative density, which also coincided with a significant increase in the cohesive strength of compacted specimens.Spatially-resolved SAXS data was also used to investigate local variations in compaction behaviour within specimens of different shape. The results revealed the expected patterns of density variations within flat-faced cylindrical specimens. Significant variations in density, the magnitude of compressive strain and principal strain direction were also revealed in the vicinity of a debossed feature (a diametral notch) and within biconvex specimens. The variations in compaction around the debossed notch, with a small region of high Clay compaction SAXS -revised PRL 2015-01-03

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Section: Bulk Compaction Behavioursupporting

confidence: 92%

mentioning

confidence: 99%

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Laity

Asare-Addo

Sweeney

et al. 2015

Applied Clay Science

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“…Consequently, reliable methods for investigating density variations are very important for understanding the characteristics and behaviour of tablets. Although other methods based on microindentation, 5 MRI to observe the distribution of a non-swelling liquid 6 and XmT 7,8 are available, the results presented here, in other recent publications 16,17 and work to be reported elsewhere 25 suggest that density measurements from SAXS can provide a very useful contribution to the subject.…”

Section: Discussionmentioning

confidence: 61%

“…Further work comparing results from SAXS analyses with predictions from FE modelling, for specimens of more complex shapes will also be reported separately. 25 …”

Section: Introductionmentioning

confidence: 99%

Variations in Compaction Behaviour for Tablets of Different Size and Shape, Revealed by Small-Angle X-Ray Scattering

Laity

Han

Elliott

et al. 2010

Journal of Pharmaceutical Sciences

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“…Combined with the fact that smaller particles have smaller masses, the dissipated energy is predicted to increase their temperature significantly during such powder processing as compaction [27]. This can be crucial for the tabletting of pharmaceutical powders, where the increase in temperature can affect the properties of the drug [28,29].…”

Section: Discussionmentioning

confidence: 99%

Effect of particle size on energy dissipation in viscoelastic granular collisions

2011

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We analyze the scaling properties of the Hertz-Kuwabara-Kono (HKK) model, which is commonly used in numerical simulations to describe the collision of macroscopic noncohesive viscoelastic spherical particles. Parameters describing the elastic and viscous properties of the material, its density, and the size of the colliding particles affect the restitution coefficient ɛ and collision time τ only via appropriate rescaling but do not change the shape of ɛ(v) and τ(v) curves, where v is the impact velocity. We have measured the restitution coefficient experimentally for relatively large (1 cm) particles of microcrystalline cellulose to deduce material parameters and then to predict collision properties for smaller microcrystalline cellulose (MCC) particles by assuming the scaling properties of the HKK model. In particular, we demonstrate that the HKK model predicts the restitution coefficient of microscopic particles of about 100 μm to be considerably smaller than that of the macroscopic particles. In fact, the energy dissipation is so large that only completely inelastic collisions occur for weakly attractive particles. We propose a straightforward self-consistent extension to the Johnson-Kendall-Roberts (JKR) model to include dissipative forces and discuss the implications of our findings for the behavior of experimental powder systems.

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Density and plastic strain evaluations using small-angle X-ray scattering and finite element simulations for powder compacts of complex shape

Cited by 13 publications

References 38 publications

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Using small-angle X-ray scattering to investigate the compaction behaviour of a granulated clay

Variations in Compaction Behaviour for Tablets of Different Size and Shape, Revealed by Small-Angle X-Ray Scattering

Effect of particle size on energy dissipation in viscoelastic granular collisions

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