Shear mixing materials

Many reactions involve shear-sensitive materials, which severely limit the maximum mixing rate and make impeller and reactor design important. Mixing becomes the limiting factor. 

Insoluble Lubricants. Lubricants act by interposing an intermediate layer between the tablet constituents and the die wall. The smaller the amount of stress needed to shear the material, the better its lubricant properties will be. Since they are primarily required to act at the tooling/material interface, lubricants should be incorporated in the final mixing step after all granulation and... 

Nienow and Elson (1988) have reviewed work done mainly by them and their co-workers on the mixing of non-Newtonian liquids in tanks. The above approach for inelastic, shearing thinning liquids has been largely substantiated but considerable doubt has been cast over using this method for dilatant, shear thickening materials. 

Nonconjugated hydrocarbon polymers could also be combined with carbon nanotubes, with polystyrene being the most studied example. The composites are generally prepared by solution or shear mixing techniques, resulting in materials with improved mechanical properties [60]. 

While the microbubbles with an albumin shell were already in development, other groups of researchers investigated the use of surfactants or fipid-stabilized microbubble shells. Pluronic-stabifized renografin-air bubbles were prepared, but their storage stability was unsatisfactory. It required sonication shear mixing immediately prior to administration into experimental animals [18]. Other materials fared considerably better. A combination of a hydrophobic Span and... 

Powder discharge process Gravity-assisted Impeller assisted BM Gravity-assisted discharge process HSDB Impeller required to discharge material from high-shear mixing vessel... 

In 1949, also in Germany, Lodige invented another important new tool for high shear mixing, the plow (Fig. 7.37). This element is fastened, in multiplicity, to a horizontal shaft as shown in Fig. 7.38 and rotates in a stationary drum (Fig. 7.38a). The rotational speed depends on the material, the diameter of the drum as well as the shape of the plows and is empirically determined to produce an intensive, three-dimensional particle motion as shown schematically in Fig. 7.38b. Often, the condition of the tur-bulently moving, aerated particle mass is described by the term mechanically fluidized . 

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