Promotion of deactivated sintering by dry‐particle coating

Mohan, Michelle Ramlakhan; Davé, Rajesh N.; Pfeffer, Robert

doi:10.1002/aic.690490307

Cited by 9 publications

(5 citation statements)

References 24 publications

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“…It has been shown that such surface modification allows for modifying and controlling properties such as cohesion, flow, sinterability (coated material can be made to sinter at a lower or higher temperature than normal), etc. [15,16]. It was also shown that dry coating is more effective than simple addition of nano silica to the cohesive powder [15].…”

Section: Introductioncontrasting

confidence: 38%

Near-Infrared Spectroscopy for the In-Line Characterization of Powder Voiding Part II: Quantification of Enhanced Flow Properties of Surface Modified Active Pharmaceutical Ingredients

et al. 2010

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In this work, dry-particle coating was used to modify the surface properties of active pharmaceutical ingredients (APIs) having extremely poor flow properties. Near-infrared (NIR) spectroscopy was utilized as a novel approach to characterize the improved flow behavior of APIs and their blends. Acetaminophen and ibuprofen were coated with nano-sized silica at two different coating levels (0.5% and 1% w/w of the API) in dry-particle coating devices viz. magnetically assisted impaction coater (MAIC) and Hybridizer. Surface modified (dry coated) APIs were then blended with excipient (spray dried lactose monohydrate) in a V-blender. As a baseline comparison to dry coating, the silica addition was also accomplished by two commonly used industry methods, i.e., passing a portion of API with silica through a sieve (sieve blending method) or blending a portion of API powder with silica in a V-blender (preblending method). Flow results showed that dry particle coated acetaminophen as well as ibuprofen blends performed significantly better than uncoated API blends at higher API concentrations. In addition, examination of the flow intensity from NIR spectra (inverse signal to noise ratio of spectra) and its standard deviation revealed that dry particle coated blends showed better uniformity of flow as compared to the other methods. Angle of repose measurements corroborated these results, showing that the majority of the blends prepared from coated APIs stayed in either passable or fair category.

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Section: Introductioncontrasting

confidence: 38%

Near-Infrared Spectroscopy for the In-Line Characterization of Powder Voiding Part II: Quantification of Enhanced Flow Properties of Surface Modified Active Pharmaceutical Ingredients

et al. 2010

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“…At that point, an additional mechanism, such as mechanical vibration or fine powder coating, has to be implemented to fluidize them. 19,40,41 As in the beds of noncohesive particles, both T and Tr͑ =͒ / D form lobes when plotted against , and manifest the same path dependence ͑Figs. 15 and 17͒.…”

Section: Effect Of Cohesionmentioning

confidence: 45%

“…For sufficiently cohesive particles (Bo >∼ 8), as one can readily expect, the maximum tensile stress driven solely by gravity fails to reach the tensile strength of the material, and the bed does not form a stable traveling wave any more. At that point, an additional mechanism, such as mechanical vibration or fine powder coating, has to be implemented to fluidize them [40,41].…”

Section: Effect Of Cohesionmentioning

confidence: 99%

Compaction and dilation rate dependence of stresses in gas-fluidized beds

2006

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A particle dynamics-based hybrid model, consisting of monodisperse spherical solid particles and volume-averaged gas hydrodynamics, is used to study traveling planar waves ͑one-dimensional traveling waves͒ of voids formed in gas-fluidized beds of narrow cross-sectional areas. Through ensemble-averaging in a co-traveling frame, we compute solid phase continuum variables ͑local volume fraction, average velocity, stress tensor, and granular temperature͒ across the waves, and examine the relations among them. We probe the consistency between such computationally obtained relations and constitutive models in the kinetic theory for granular materials which are widely used in the two-fluid modeling approach to fluidized beds. We demonstrate that solid phase continuum variables exhibit appreciable "path dependence," which is not captured by the commonly used kinetic theory-based models. We show that this path dependence is associated with the large rates of dilation and compaction that occur in the wave. We also examine the relations among solid phase continuum variables in beds of cohesive particles, which yield the same path dependence. Our results both for beds of cohesive and noncohesive particles suggest that path-dependent constitutive models need to be developed.

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“…That may explain why the dry-coated samples are well dispersed, and there are no solid bridges observed in the SEM images. The influence of dry coating on altering surface properties has also been shown in the previous study, 54 where dry coating by nanosized silica was used to increase the sintering temperature, thus reducing the sintering rate of glass beads, poly(methyl methacrylate) (PMMA) and γ-alumina. In the current work, dry coating appears to prevent aggregation that may be based on sintering or solid bridging.…”

Section: Particle Scale Characteristicsmentioning

confidence: 46%

Passivation of High-Surface-Energy Sites of Milled Ibuprofen Crystals via Dry Coating for Reduced Cohesion and Improved Flowability

Han

Jallo

et al. 2013

Journal of Pharmaceutical Sciences

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Promotion of deactivated sintering by dry‐particle coating

Abstract: Dry-particle coating was used to examine the feasibility of increasing

Cited by 9 publications

References 24 publications

Near-Infrared Spectroscopy for the In-Line Characterization of Powder Voiding Part II: Quantification of Enhanced Flow Properties of Surface Modified Active Pharmaceutical Ingredients

Near-Infrared Spectroscopy for the In-Line Characterization of Powder Voiding Part II: Quantification of Enhanced Flow Properties of Surface Modified Active Pharmaceutical Ingredients

Compaction and dilation rate dependence of stresses in gas-fluidized beds

Passivation of High-Surface-Energy Sites of Milled Ibuprofen Crystals via Dry Coating for Reduced Cohesion and Improved Flowability

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