Compression powder flow

The bulk density of a powder is calculated by dividing its mass by the volume occupied by the powder (Abdullah Geldart, 1999). Tapped bulk density, or simply tapped density, is the maximum packing density of a powder achieved under the influence of well-defined, externally applied forces (Oliveira et al., 2010). Because the volume includes the spaces between particles as well as the envelope volumes of the particles themselves, the bulk and tapped density of a powder are highly dependent on how the particles are packed. This fact is related to the morphology of its particles and such parameters are able to predict the powder flow properties and its compressibility. 

Amidon and Houghton [48] completed a comparative study of several common methods of characterizing powder flow. Table 2 contains experimental results for a number of commonly used pharmaceutical excipients. Compressibility index, angle of repose, flow rate through an orifice, and shear cell data are presented. 

In recent years the compressibility index Ci( has become a simple, fast, and popular method of predicting powder flow characteristics [40,42-44,51,52]. Carr [42-44] proposed its use as an indirect measure of bulk density, size and shape,... 

The pellets are prepared by compressing the powder. The powder flows through a feeder mechanism, and is filled into a rotating die, where it is compressed by pistons. 

In previous work, the formula used were optimized by direct compression [13]. The area under the dissolution curve was optimized and validated by a composite design. However, the formulation gave poor powder flow as well as variability in the dissolution parameters. Thus the double compression process was investigated in order to change the powder into solid aggregates and therefore to enhance homogeneity, density and powder flow in addition it was expected that this process would reduce the variability between tablets. 

The area under the dissolution curve (AUC=T6), was chosen as the major response to be optimized. Nevertheless, the results showed that it is necessary to study several properties to define the best formulation adequate powder flow, compression behaviour and particularly, a minimal variability of the dissolution parameters [3]. It was noted that good powder flow rate is not always related to an adequate compression behaviour [4]. 

Menon A, Gillece T, Chakrabarti S. Co-processing method for making a free flowing compressible powder and tablet therefrom. US Patent No. 5,560,927, 1996. 

The critical unit operations that should be monitored and/or optimized are the reaction and fermentation steps for the purpose of increasing API yield and reducing the residual impurity profile. Other critical unit operations that are especially important to the end user (pharmaceutical dosage form operations) include precipitation or crystallization, milling, sizing, and purification operations, which may affect the physical properties (particle size and shape, bulk powder flow, blend uniformity, and compressibility) of the API. 

Powder flow and compressibility characterization Heavy metals and arsenic content... 

Chitin was evaluated as a direct-compression vehicle using powder flow properties and the physicomechanical properties of the manufactured tablets, and it was proven that this natural polymer has suitable characteristics for being used for this end. 

The electrolyte constitutes a separator for the gas flows shown in Fig. 3.16, in addition to providing ionic transport. Physically, it consists of a compressed powder behaving as a soft paste at the operating temperatures, thus substantiating the name "molten carbonate" for the liquid Li-Na or Li-K carbonates inhabiting the electrolyte substrate. The LiAlOj material used for the support structure can exist in three different forms (phase a, P and fj, and transitions have been observed (e.g., yto d) after extended fuel cell operation... 

To improve powder flow properties for dosage filling and compression processes... 

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