The compression mechanism of powders

Kennedy, Tadhg; Yaginuma, Yoshihito; Hampshire, Stuart

doi:10.1016/0924-0136(95)01872-7

Cited by 2 publications

(2 citation statements)

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“…It is believed that the external pressure is able to inhibit grain growth by decreasing the mass diffusivity and grain boundary mobility at high temperature [17]. Simultaneously, external pressure can also facilitate densification by assisting particle rearrangement, increasing sintering kinetics and promoting diffusion creep [15,18,19].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of zirconia ceramics consolidated by a novel oscillatory pressure sintering

Xie

Xue

2015

Ceramics International

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Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of zirconia ceramics consolidated by a novel oscillatory pressure sintering

Xie

Xue

2015

Ceramics International

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“…Mathematical models have been used to describe the consolidation or volume reduction of powders. Such models were derived from empirical mathematical relationships and were based on the proposal that different mechanisms occur in distinct ranges of applied pressure (Kennedy et al, 1996). These models are used to characterize tableting excipients for compact development.…”

Section: Powder Consolidation Modelsmentioning

confidence: 99%

Assessment of co-processing of cellulose II and silicon dioxide as a platform to enhance excipient functionality

Rojas¹

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This thesis project studied microcrystalline cellulose II (CII), a polymorphic form of cellulose, which has lower mechanical properties, less plastic deformation, higher elastic recovery and faster disintegration properties than microcrystalline cellulose I (CI). Also, the effects of processing and silicification on CII materials were investigated. Particle modification through spray drying, wet granulation and spheronization was employed to improve CII performance. Spray-drying (SDCII) and wet granulation (WGCII) produced materials with no difference in mechanical or disintegration properties from unprocessed CII, but did show an increase in density and particle flow. Conversely, spheronization (SPCII) showed the poorest mechanical properties compared to CII. Further, SDCII showed better dilution potential than CII. Thus the advantages of SDCII were apparent when it was mixed with a poorly compressible drug (acetaminophen) because fibrous CII was converted to spheroidal particles through spray drying. The rapid disintegration of SDCII and CII compacts was due to water wicking through capillaries followed by compact bursting. Compacts of ibuprofen mixed with SDCII and Avicel ® PH-102 had comparable disintegration rates and release profiles compared to ibuprofen formulated with commercial disintegrants and Avicel ® PH-102, especially at levels 10% w/w. Adding fumed silica into CII particles through spray drying, wet granulation (WGCII) and spheronization (SPCII) at 2-20% w/w was also studied. Silicification increased physical properties such as true density, Hausner ratio, porosity, ejection force and specific surface area of SDCII and WGCII. Other properties such as bulk and tap densities were reduced due to the amorphous and light character of fumed silica. Spheronized CII showed no change in these properties with silicification. Silicification diminished lubricant sensitivity with magnesium stearate due to the competition of SiO 2 with magnesium stearate to coat CII particles. Silicification also decreased the affinity of CII for water only at the 20% w/w level due to the few silanol groups available for water interaction compared to surface hydroxyl groups on CII alone. Particle size modification of CII was process-dependent v transformed my vision of the role of pharmaceutics and physical pharmacy for drug development. I also appreciate their financial support and the initial support provided by University of Antioquia, especially to Professors Tobon and Bedoya. I also express my gratitude to Dr. Reist for his trust, support and teaching me the value of professionalism and personalized pedagogy in the Pharmacy Practice Laboratory.

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The compression mechanism of powders

Cited by 2 publications

References 14 publications

Microstructure and mechanical properties of zirconia ceramics consolidated by a novel oscillatory pressure sintering

Microstructure and mechanical properties of zirconia ceramics consolidated by a novel oscillatory pressure sintering

Assessment of co-processing of cellulose II and silicon dioxide as a platform to enhance excipient functionality

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