Polydisperse powders

This can be done via Eqs. (29) through (32). From the dissolution data, the coefficient B2 is obtained and through the results from microscopy the moments r2 and p3 can be evaluated. By knowing N, the initial number of particles, and the density of the solid, the average initial volume shape factor for a polydisperse powder can be estimated. 

ATK Lu, ME Frisella, KC Johnson. Dissolution modeling Factors affecting the dissolution rates of polydisperse powders. Pharm Res 10 1308-1314, 1993. 

Swaminathan V. Kildsig D. Polydisperse powder mixtures Effect of particle size and shape on mixture stability. Drug Dev Ind Pharm 2002 28(l) 41-8. 

Ti02 powders can be readily obtained from the hydrolysis and condensation of titanium alkoxides. However such precursors are highly reactive, leading to the uncontrolled precipitation of polydispersed powders upon addition of... 

Vibration combined with upward flow of air in an aerated bed enables particles to pseudofluidize smoothly. The gas velocity required for minimum fluidization is considerably lower than the minimum fluidization velocity in a conventional FBD. Attrition due to vigorous actions between particle-particle and particle-wall is thus minimized appreciably. Hence, application of fluidized bed can be extended to fragile, abrasive, and heat-sensitive materials. The problem of fine particle entrainment is also avoided. For polydisperse powders, low gas velocity fluidizes the fine particles gently, whereas vibration keeps the coarse particles in a mobile state. 

The completeness of removal of monodisperse particles can be defined by means of Eqs. (I.2)-(I.4) in cases in which the same detachment force is acting on these particles. In cases in which a certain detachment force acts on particles of different sizes in a polydisperse powder fraction, the detachment results will not be the same for the different particles. The coarse particles will be removed... 

Polydisperse powders can be separated into fractions in this vibroseparator, for example into fractions <5, 5-10,10-20, and 20-30 jum. The productive capacity this apparatus depends on the particle size distribution of the powder being separated. In separating 1 kg of powder consisting of particles with diam-... 

S. Sato, J. H. Pinsent, D. Y. H. Pui, The Characterization of Particle Size fiir Polydispersed Powders Aerosolized and Detected by Light-Scattering , Part. Part. Syst. Charact., 13 (1996) 234-237. 

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