A comparison of ram extrusion by single-holed and multi-holed dies for extrusion–spheronisation of microcrystalline-based pastes

Zhang, M.; Rough, S.L.; Ward, R.; Seiler, Christian; Wilson, D.I.

doi:10.1016/j.ijpharm.2011.06.043

Cited by 19 publications

(41 citation statements)

References 16 publications

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“…Severe LPM or LPM-related phenomena such as pooling of free water were not observed in the LRS tests, confirming that LRS extrusion, operating in wiping mode, could work at low velocities (<1 mm s −1 ) representative of industrial screen extruders without promoting LPM. The estimated ˙ app values ranged from 0.16 to 7.44 s −1 , which are considerably lower than the values estimated for an industrial unit by Zhang et al (2011), of 600-10,000 s −1 . Higher extrusion rates could be achieved by the LRS but require automated, faster feeding.…”

Section: Paste Densitycontrasting

confidence: 64%

“…The rheological behaviour of the paste was reported by Zhang et al (2011) in their study of ram extrusion (and subsequent spheronisation of this material) using multi-holed dies. The products obtained after spheronisation of the extrudates are here termed pellets.…”

Section: Introductionmentioning

confidence: 69%

“…A Beckman Coulter LS230 laser diffraction instrument (Coulter Electronics Limited, Bedfordshire, UK) was used as by Zhang et al (2011) for MCC particle sizing analysis. The particle sizes lay in the range of 2-260 m with a Sauter mean diameter of 49.1 m. Zhang et al also reported rheological characterisation of the paste using ram extrusion through single-holed dies according to the Benbow-Bridgwater method (Benbow and Bridgwater, 1993).…”

Section: Materials and Paste Preparationmentioning

confidence: 99%

“…The extrudate velocities lie in the range 0.02-0.93 mm s −1 . Zhang et al (2011) reported that ram extrusion of a similar paste using single-holed (percentage hole area, 0.16%) and 137-holed (percentage hole area of 21.9%) dies encountered LPM at v ex values less than 31 and 1 mm s −1 , respectively. Severe LPM or LPM-related phenomena such as pooling of free water were not observed in the LRS tests, confirming that LRS extrusion, operating in wiping mode, could work at low velocities (<1 mm s −1 ) representative of industrial screen extruders without promoting LPM.…”

Section: Paste Densitymentioning

confidence: 99%

“…The LRS is used here with a simple 45 wt% MCC/water based paste studied previously (Zhang et al, 2011) to gain an understanding of screen devices, paste flow behaviour, the influence of the nip size and the quality of the spheronised extrudates. The rheological behaviour of the paste was reported by Zhang et al (2011) in their study of ram extrusion (and subsequent spheronisation of this material) using multi-holed dies.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A novel lab-scale screen extruder for studying extrusion-spheronisation

Zhang

Mascia

Rough

et al. 2013

International Journal of Pharmaceutics

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Section: Paste Densitycontrasting

confidence: 64%

Section: Introductionmentioning

confidence: 69%

Section: Materials and Paste Preparationmentioning

confidence: 99%

Section: Paste Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A novel lab-scale screen extruder for studying extrusion-spheronisation

Zhang

Mascia

Rough

et al. 2013

International Journal of Pharmaceutics

Self Cite

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Linking particle properties to dense suspension extrusion flow characteristics using discrete element simulations

et al. 2017

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Extrusion is a widely used process for forming pastes into designed shapes, and is central to the manufacture of many industrial products. The extrusion through a square-entry die of a model paste of non-Brownian spheres suspended in a Newtonian fluid is investigated using discrete element simulations, capturing individual particle contacts and hydrodynamic interactions. The simulations reveal inhomogeneous velocity and stress distributions, originating in the inherent microstructure formed by the constituent particles. Such features are shown to be relevant to generic paste extrusion behaviour, such as die swell. The pressure drop across the extruder is correlated with the extrudate velocity using the Benbow-Bridgwater equation, with the empirical parameters being linked directly to particle properties such as surface friction, and processing conditions such as extruder wall roughness. Our model and results bring recent advances in suspension rheology into an industrial setting, laying foundations for future model development, paste formulation and extrusion design. arXiv:1608.06188v1 [cond-mat.soft]

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Modeling the breakage stage in spheronization of cylindrical paste extrudates

Wang

Lim

et al. 2021

AIChE Journal

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Spheronization of cylindrical extrudates on a rotating friction plate involves breakage and rounding. Little attention has been given to the breakage stage and quantitative modeling of this process is scarce. Two simple models are compared with experimental data obtained for the early stages of spheronization of microcrystalline cellulose/water extrudates. Tests were conducted for different times (t), rotational speeds (ω), initial loadings, and on pyramidal friction plates with different dimensions. The first model, describing the number of pellets, validated ω 3 t as a characteristic time scale for the breakage stage. The kinetic parameters obtained by fitting showed a systematic dependence on plate dimensions expressed as a scaled gap width. The second model, a simple population balance, described the evolution of the number and length of pellets. The pseudo rate constants provided insights into the kinetics: extrudates tended to break near the middle, while breakage of smaller pellets was slowed down by more pellet-pellet collisions.

show abstract

A comparison of ram extrusion by single-holed and multi-holed dies for extrusion–spheronisation of microcrystalline-based pastes

Cited by 19 publications

References 16 publications

A novel lab-scale screen extruder for studying extrusion-spheronisation

A novel lab-scale screen extruder for studying extrusion-spheronisation

Linking particle properties to dense suspension extrusion flow characteristics using discrete element simulations

Modeling the breakage stage in spheronization of cylindrical paste extrudates

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