High-shear equipment

Thermoplastic elastomers that are hard polymer/elastomer combinations are often not truly synthesized. Instead, the two polymers that form the hard and soft phases are intimately mixed on high shear equipment. 

High shear wet grinding equipment can reduce the particle size of the active ingredient to the needed size range and also activate the clays used in many formulations to stabilize the suspension. High shear equipment has not always been used for production of dispersions. 

Based on the machine design parameters, high-shear granulation equipment of the same type will usually vary less in tip speed, Froude number, and RSV upon scale-up in equipment size. The differences in Froude number and RSV among high-shear mixers of different types are less as the size of the equipment increases. Therefore, development and scale-up are easier if the same type of high-shear equipment is used. 

Among the factors impacting binder performance in high shear equipment are the binder quantity, binder addition method (wet vs dry), solvent quantity, solvent addition rate and method (spray vs open tube), wet massing time, impeller speed, chopper speed, and equipment design and these parameters need to be optimized during the development process, typically with the aid of a statistically designed set of experiments. 

Active or mechanical material transfer with a high degree of induced shear is performed by what is known as high-shear equipment ... 

In another patented process, starch was destructurized in the presence of low molecular weight polymers such as polyethylene-vinyl alcohol (EVOH), EAA, poly-e-caprolactone and small amounts of moisture and of a high boiling point plasticizer, using a high shear equipment like a twin-screw extruder [77]. From these materials emerged one of the most successful commercial thermoplastic materials based on starch, which took the name of Mate-Bi . 

Carbon blacks are supplied as powder or pellets. Powders are confined mostly to dry blending. Pellets are preferred for concentrates, with high-shear equipment mandatory. Micropulverized delayed coke, a relatively new form of carbon black, is a coarse filler offered as an alternative to thermal blacks for tinting and UV stabilization in some uses. 

Figure 5-5X. Type R-500. Very high shear radial flow impeller for particle size reduction and uniform dispersion in liquids. By permission, Lightnin, (Formerly Mixing Equipment Co.) a unit of General Signal.

Sulfonation plants are normally equipped with neutralization units based on pressure recycle loops, simple or multistage, composed of in-line high-shear... 

To prepare nanoparticles based on water-insoluble polymers, a solution of the polymer in an organic solvent can be emulsified within an aqueous phase. This O/W emulsion is then homogenized under high shear with an appropriate homogenization equipment... 

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