Flow Function of Pharmaceutical Powders Is Predominantly Governed by Cohesion, Not by Friction Coefficients

Leung, Lap Yin; Chen, Mao; Srivastava, Ishan; Du, Ping; Yang, Chia-Yi

doi:10.1016/j.xphs.2017.04.012

Cited by 39 publications

(30 citation statements)

References 15 publications

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“…The results from Tables 1 and 2 corroborate this notion. 15 The wall friction angles, against stainless steel with 2B surface finish, are presented in Figure 3. The addition of 0.2% colloidal silicon dioxide slightly reduces the wall friction angle, but the difference between 2 powder blends diminishes at lower stresses.…”

Section: Experimental Considerations and Test Resultsmentioning

confidence: 99%

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A Proposed Complete Methodology to Predict Gravity Flow Obstruction of Pharmaceutical Powders in Drug Product Manufacturing

Leung

Chen

Pieters

et al. 2019

Journal of Pharmaceutical Sciences

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We present herein a comprehensive methodology to evaluate the risks involved in gravity-driven flow of pharmaceutical powders, including mass flow/funnel flow pattern, arch formation under active stress state (initial discharging) and passive stress state (following initial discharging), and rathole formation. Built on original theories underpinning the hopper design procedure, the methodology was modified to accommodate practices of pharmaceutical powder handling. All data required are generated from conventional ring shear tester. We applied the methodology to evaluate the powder flow risks during drug product manufacturing campaigns, where two powder blends with distinct flow behavior were discharged from a 200-L bin. The predicted results are in agreement with experiments where visual observations were possible, including the flow pattern, arch formation under active stress state, and rathole formation. One notable discovery is that pharmaceutical powders exhibit high risk of arch formation under active stress state, because of the exceeding major principal stress than the passive state. This phenomenon has been so far overlooked and the existing flow function-based classification cannot capture this risk. We propose, through this methodology, that reliable powder flow assessment should consider factors preventing flow (i.e., flow function), as well as factors facilitating flow (i.e., external stress).

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Section: Experimental Considerations and Test Resultsmentioning

confidence: 99%

“…14 The major principal stress of the bulk powder can be determined according to the method on the stress calculation under the active stress condition, which is presented in the preceding section (Eqs. [7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Estimation Of Stable Rathole Formationmentioning

confidence: 99%

A Proposed Complete Methodology to Predict Gravity Flow Obstruction of Pharmaceutical Powders in Drug Product Manufacturing

Leung

Chen

Pieters

et al. 2019

Journal of Pharmaceutical Sciences

Self Cite

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“…Crawford et al (2016) used it to study the effect of preprocessing of biomass and Léonard and Abatzoglou (2010) to investigate lubricated and unlubricated pharmaceutical powders. The FT4 shear cell was also used by Leung et al (2017) to investigate the flowability of pharmaceutical powders mainly driven by cohesion.…”

Section: Rotational Shear Testersmentioning

confidence: 99%

From Quasi-static to Intermediate Regimes in Shear Cell Devices: Theory and Characterisation

Francia

Yahia

Ocone

et al. 2021

KONA

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The design of new technology for processing and manufacturing particulate products requires understanding granular rheology over a broad range of conditions. Powders display a complex behaviour due to their ability to rearrange under stress, and as a result, granular flow is generally classified into three flow regimes, namely a quasi-static regime dominated by frictional contacts, an inertial regime dominated by collisional and kinematic stresses and an intermediate regime where the three sources of stress are important to establish a stress-strain rate relationship. Characterisation of the flowability is generally restricted to the flow initiation in quasi-static regime, even if, transition into inertial conditions is very common in practical applications involving the control of dense flows, such as powder handling, particle formation processes or additive manufacturing. This work presents a critical review of available techniques to characterise the departure from the quasi-static regime into an intermediate flow. We revise the application of shear cells and present different strategies to modify classic devices with external actuation, such as aeration, to operate at higher inertial numbers. We pay particular attention to innovative designs using aerated Couette flow configurations, highlight the complexity in the standardisation and the challenges in advancing towards a universal model.

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“…[3][4][5][6] From powder shear tests, flow properties, such as cohesion, unconfined yield strength, s c , bulk density, r B , and various angles of friction, are obtained at the defined major principal stress, s 1 , which is also the consolidation stress. 7 The ratio of s 1 to the corresponding s c , normally represented as ff c , has been a useful parameter for classifying the "flowability" of bulk solids. A lower ff c is an indicator of poorer flowability.…”

Section: Introductionmentioning

confidence: 99%

“…A lower ff c is an indicator of poorer flowability. [6][7][8][9] Typically, formulation scientists rank order the ff c of materials to select the bulk solid with better flowability. 10,11 This is an attractive approach because it spares material and time; however, a single ff c provides no information on the stress dependence of powder flowability.…”

Section: Introductionmentioning

confidence: 99%

Impact of Shear History on Powder Flow Characterization Using a Ring Shear Tester

Swize

Osei-Yeboah

Peterson

et al. 2019

Journal of Pharmaceutical Sciences

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In this study, we have investigated the impact of repeated shear displacement on powder flow properties. We show that when multiple yield loci are obtained using the same bulk solid specimen by stepping through different stress levels (i.e., stress walk [SW]), the shear deformation of the powder in a rotational shear cell, that is, Schulze Ring Shear Tester, is maximized, reducing the powder shear strength. This approach is material and time sparing; however, it imprecisely predicts better powder flowability. The magnitude of the change in the unconfined yield strength, σ, due to this prolonged shear displacement appears to be material-dependent, being less impactful for free-flowing powders. Using the SW and the individual yield loci-generated flow properties, we have demonstrated that in hopper design, the shear displacement effect impacts the computed critical arching diameter more than the critical mass flow angle. This knowledge of powder flow properties highlights limitations associated with the SW. An exponential function was found to describe the relationship between the change in σ at the highest major principal stress and the density weighted flowability, ff, with an R of 0.98. Such a model could be a valuable tool for correcting shear strength results obtained from SW, saving time, and material.

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Flow Function of Pharmaceutical Powders Is Predominantly Governed by Cohesion, Not by Friction Coefficients

Cited by 39 publications

References 15 publications

A Proposed Complete Methodology to Predict Gravity Flow Obstruction of Pharmaceutical Powders in Drug Product Manufacturing

A Proposed Complete Methodology to Predict Gravity Flow Obstruction of Pharmaceutical Powders in Drug Product Manufacturing

From Quasi-static to Intermediate Regimes in Shear Cell Devices: Theory and Characterisation

Impact of Shear History on Powder Flow Characterization Using a Ring Shear Tester

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