A numerical investigation of air flow during tablet compression

Kremer, D M.

doi:10.1016/j.ces.2006.09.038

Cited by 2 publications

(2 citation statements)

References 31 publications

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“…At standard temperature and pressure, the adsorbed layer on the surface and in the pores of the powder particle are in liquid mono, or multilayer states [36]. However, because the compression process is very fast and the powder has a low water content, the water is assumed to flow mainly in vapor form in high-velocity dry air [35,37], but the liquid form may still exist in the capillaries due to the hygroscopic powder particle. Hence, in the moisture transport equations, the liquid form of water is considered [30].…”

Section: Mathematical Modelmentioning

confidence: 99%

Moisture Transport Coefficients Determination on a Model Pharmaceutical Tablet

2022

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In this work, a novel methodology to determine moisture transport coefficients for MMC PH101 tablets is presented. Absolute permeability, moisture diffusion, moisture transfer, and water vapor permeability coefficients were estimated on compressed powder tablets produced with different compression pressures (20 MPa to 200 MPa with an interval of 20 MPa). The ASTM D6539 standard test was used to measure the absolute permeability. The moisture transfer coefficient was determined from measured absolute permeability. The moisture diffusion coefficient was obtained with the tablet average pore radius, which was determined with the water droplet penetration method. Descriptive and phenomenological models derived from the measurements were confronted with existing and adopted models, and a good agreement was found. The obtained models are of the function of the microstructural properties of the tablet (average pore radius and average porosity). The tablet average porosity was found to be the principal parameter that governs the behavior of the moisture transport coefficients. The findings of this study might be applicable to obtain a series of input parameters for modelling software, such as COMSOL Multiphysics®, to infer delamination, sticking, and failure propensity from the effect of moisture.

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Section: Mathematical Modelmentioning

confidence: 99%

Moisture Transport Coefficients Determination on a Model Pharmaceutical Tablet

2022

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“…12 Numerical studies examining the increase of air pressure and flow of air within the die during compaction are limited. Kremer 13 investigated through computational fluid dynamics the flow of gas in a die cavity on compaction. In this work, there was no solid material consolidation considered and only air movement on tableting in an empty die.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Air Pressure Increase Within a Powder Bed During Compression—A Step Toward Understanding Tablet Defects

Klinzing

Troup

2019

Journal of Pharmaceutical Sciences

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The cause of tablet defects, such as cracking, bubbling, and capping, during compression is currently not fully understood. Prior experimental work suggests that an increase in internal air pressure on powder compression can directly contribute to the formation of cracks within a tablet. The present study examines the air pressure increase on compression in a fully two-dimensional axisymmetric tablet geometry while being coupled to a plasticity model describing the evolution of tablet relative density on consolidation. It is shown numerically that increasing compression speed results in a large air pressure increase on the order of 1-1.5 MPa which approaches the diametrical tensile strength of tablets. In addition, it is shown experimentally through X-ray microcomputed tomography scans of tablets made at various dwell times that increasing dwell times equivalent to that on a tablet press has no effect on the degree of cracking within the tablet. Only when dwell times reach a time scale of 10 to 100 s does the air pressure diminish to a point at which cracking is eliminated. The reduction in air pressure during these extended dwells is captured by the current model. The experimental and numerical work presented here couples for the first time an air pressure model and plasticity model on compression. In addition, it provides a foundation for understanding how realistic tableting aspects such as precompression and tablet size impact the air pressure increase on consolidation.

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A numerical investigation of air flow during tablet compression

Cited by 2 publications

References 31 publications

Moisture Transport Coefficients Determination on a Model Pharmaceutical Tablet

Moisture Transport Coefficients Determination on a Model Pharmaceutical Tablet

Modeling the Air Pressure Increase Within a Powder Bed During Compression—A Step Toward Understanding Tablet Defects

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