Flowability, powder

The cost/performance factor of individual surfactants will always be considered in determining which surfactants are blended in a mixed active formulation. However, with the recent advent of compact powders and concentrated liquids, other factors, such as processing, density, powder flowability, water content, stabilization of additives, dispersibility in nonaqueous solvents, dispersion of builders, and liquid crystalline phase behavior, have become important in determining the selection of individual surfactants. 

SB Tan, JM Newton. Powder flowability as an indication of capsule filling performance. Int J Pharm 61 145-155, 1990. 

The bulk density of the powder inside the die is called the fill density, Djm. A high fill density reduces both the air content in the powder and the distance the punch needs to travel to further compress the powder during pressing. Poor powder flowability... 

Prescott JK, Barnum RA. On powder flowability. Pharm Technol 2000 24(10) 60-236. 

Kurihara K, Ichikawa I. Effect of powder flowability on capsule filling weight variation. Chem Pharm Bull 1978 26 1250-1256. 

P. Maijanovic, D. Geldart, J.L.R. Orband, Techniques for assessing powder flowability - a comparison, Proceedings of the World Congress on Particle Technology 3, Brighton, UK, July 1998. 

Prescott JK, Bamum RA. 2000. On powder flowability. Pharm. Technol. 24 60-84. 

Powder flowability is measured empirically as the time for a standardized mass of powder to flow out of a horizontal rotating drum through slits in the drum wall. Drum dimensions and rotational speed are standardized. 

TABLE 15 Carr Index Classification and Powder Flowability... 

Description Catalyst in mineral-oil-slurry is metered into the reactor together with co-catalyst and modifier. The proprietary supported catalyst developed by BP has control morphology, super-high activity and very high sterospecifity. The resulting PP product is characterized by narrow particle size distribution, good powder flowability, minimum catalyst residues, noncorrosiveness, excellent color and low odor. 

Increase solids mixing. Improve powder flowability of feed. Increase agitation intensity (e g., impeller speed, fluidization gas velocity, or rotation speed). 

Several strains of the Bacillus thuringiensis are pathogenic to some insects. The bacterial organisms are cultured, then harvested in spore form for use as insecticide. Production methods vary widely. Proteinaceous and nu-cleotide-like toxins generated by the vegetative forms (which infect insects) are responsible for the insecticidal effect. The spores are formulated as wettable powders, flowable concentrates and granules for application to field crops and for control of mosquitoes and black flies. 

Fig. 9 Descriptive drawing of a rotating drum avalanche test device. This device is commercially available as the TSI Aero-Flow automated powder flowability analyzer. The top pictures the device. The progress of powder avalanche shows the position of the powder in the drum as the drum is rotated and the lower voltage output shows the output of the device during each drum rotation. (From Ref. °. )...

Fig. 10 Rotating drum avalanche data from a TSI Aero-Flow automated powder flowability analyzer. The first frame shows the data output for lactose, which passed through a 38-pm screen (less than 38-pm). The output data for the original lactose sample (notscreened) is shown in the middle frame. The last frame shows the flow data for the lactose sample remaining on the 38- j,m screen (greater than 38-pm). (From Ref l)...

Schulze D. Measuring powder flowability A comparison of test methods. Part 1. Powder Bulk Eng 1996 tO(4) 4S-61. 

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