Shearing 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. 

Comminution, or particle size reduction of solids, is considerably different from that of the breakup of one liquid by dispersal as small droplets in another. Particle size reduction is generally achieved by one of four mechanisms (1) compression, (2) impact, (3) attrition and (4) cutting or shear. Equipment for particle size reduction or milling includes crushers (which operate by compression, e.g., crushing rolls), grinders (which operate principally by impact and attrition, although some compression may be involved, e.g.,... 

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. 

Equipment used for active or passive material transfer, with a low degree of induced shear, is classified as low-shear equipment ... 

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

Mix until a creamy mixture is obtained. Load Bentone 38 by sifting or screening if low shear equipment is used. 

The bursters removed from the munitions are then sheared to access the energetic materials. The sheared burster parts and fuzes are then transferred to the ERH. The shearing step is a mechanical cutting operation involving shearing equipment used in the baseline disassembly process and in nonchemical weapons applications. All propellant material removed either from the storage containers or from the munitions is fed into the ERH along with the fuzes and sheared bursters. 

When selecting shearing equipment, it is essential that the buyer understands the advantages and disadvantages of each design, the operating variables, and the principles of shearing to ensure that the machine of choice is one that is most suitable for his particular operation. 

The choice of shearing equipment range from manual, to pneumatic, mechanical, and hydraulic operation to drive the crosshead through the work stroke. The basic function of the method of operation is to successfully move the crosshead and blade through the material to produce an acceptable cut. The shearing application usually determines the method of operation needed to achie ve production requirements. 

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. 

Umbrell-CoaKer Shearicon. Semiautomatic image-shearing equipment to size particles or features observed by optical microscopy, or of images from optical or electron photomicrographs, or a television picture. J.Powder Bulk Solids Technol. 3 (1), 26,1979). 

Features Good salt and alkali stability withstands alkaline conditions of the chlorine, chlorite, or peroxygen bleaching systems fast wetting for low shear equip. Properties Cl. liq. sp.gr. 1.03 dens. 8.59 Ib/gal pH 6.0 (1%)... 

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