Flowables

Fats contribute to the rheological properties in flowable and pastry foods. By combining with starches to form a clathrate, a product different from the native starch is formed, eg, shortening in baked goods. The highly developed shortness of pies baked in eadier times resulted from the use of high levels of lard. The use of less fat in pie cmsts is evident, ie, the cmsts are harder and readily become soggy. 

Prolonged Action Parenterals Injections. Intramuscular injections have been developed to achieve prolonged therapeutic effects. This can be accompHshed by suspension of dmg particles in oils or flowable gels, from which the dmg slowly diffuses. Aqueous suspensions can also provide such therapeutic response. In these cases, the soHd dmg crystals generally are quite water insoluble and of a controlled particle size and crystallized form. 

Mewtonian andMon-Mewtonian Materials. A Newtonian material s viscosity is shear-independent, whereas non-Newtonian materials are shear-dependent (Eig. 7). Eor most potting materials, a Newtonian material is preferred because the material is required to flow under all electronic components, but not be susceptible to shear. However, when flowable material is used for conformal coating appHcations, a non-Newtonian material with thixotropy agent added is desired since the material should flow on the electronic substrate but stop at the edge without creeping or mnover at the circuitry. 

Plow chaiacterlstic.s. Angle of repose and flowability are measurable charac teristics for which standard tests are available (e.g., ASTM Test B213-48, Flow Rate of Metal Powders, etc.). A steeper angle of repose would indicate less flowability. The term Hubricity has sometimes been used for solid particles to correspond roughly to viscosity of a fluid. 

Larger amounts of clay are being produced in diy powdered form [Anon., Ceramics Forum International, 67(7-8), 330-4 (1990)]. After grinding, the clay is agglomerated to a flowable powder with water mist in a balling drum. 

Flowability Very free-flowing—angle of repose up to 30 1... 

Age appears to improve the flowability of certain materials. This is probably the result of particle-surface oxidation, more even moisture distribution, and the rounding of particle corners caused by handhng. 

Oil content does not materially decrease flowability. For example, the addition of oils and fats to animal-feed ingredients improves the quahty of pellets made from these materials, making the pellet surfaces harder and enabling the pellets to resist attrition. 

As another consequence of the properties of the siloxane bond, the value of n in the common linear trimethylsiloxy-endblocked-PDMS, (M-D -M) can vary from zero to tens of thousands giving a range of viscosity from 0.65 to 2,500,000 centipoise to the polymeric material. This relationship between viscosity and polymer chain length allows PDMS polymers to vary in form from water-like fluids to a flowable gum, while retaining the same chemical character. 

Moisture can significantly affect loose materials, particularly their flowability. Low temperatures, particle bridging, and caking can alter interparticle void fractions and cause dramatic changes in bulk density. Moisture becomes bound to solids because of mechanical, physicochemical, and chemical mechanisms. Moisture retained... 

In addition to the physical properties just described there are those properties which affect the flowability of the material. Specifically, these properties are the material s angle of repose, angle of internal friction, and the angle of slide. 

What is the effect of moisture on the flowability and feeding characteristics of dry bulk filter aids ... 

Elongation, tensile strength, hardness, snappiness, good flowability, easy vulcanization, weatherability. ozone resistance, heat resistance, skid resistance, abrasion resistance Flowability, injection molding processability easy vulcanization, weatherability, ozone resistance, heat resistance, skid resistance, abrasion resistance, snappiness Green strength, flowability, extmdability injection molding processability, weatherability, ozone resistance, heat resistance snappiness... 

Less volatile solvents with a higher flash point, used for agricultural formulations (Catanach and Hampton, 1992). In many cases, aqueous or dry flowable formulations for agricultural chemicals may be used instead of organic formulations... 

Flow property Flowable Flowable Flowable Flowable... 

STIFFNESS, TOUCHINESS, FLOWABILITY, HEAT DISTORTION TEMPERATURE, STRESS CRACK RESISTANCE, GLOSS, TRANSPARENCY, WEATHER RESISTANCE, CREEP etc.)... 

It has been found that, for a fixed mineral filler content, the viscosity of PMF-based composites increases when the coat is made of polyethylene [164, 209, 293], poly(vinyl chloride) [316] and polypropylene [326, 327], The picture was different, however, for composites based on the ethylene/vinyl acetate copolymer to which kaolin with grafted poly (vinyl acetate) was added [336]. Addition of PMF with a minimum quantity of grafted polymer results in a sharp drop of flowability (rise of viscosity), in comparison to addition of unmodified filler but with a further increase of the quantity of grafted polymer the flow gradually increases and, depending on the kaolin content and quantity of grafted polymer, may even become higher than in specimens with unmodified filler, for equal concentrations. 

The process basically forms the sheet after it has been heated to the point at which it is soft and flowable, and then applying differential pressure (atmospheric pressure, air pressure, vacuum, or their combinations) to make the sheet or film conform to the shape of the male or female mold producing many different products (Table 8-23). The more precise and controlled pressure applied, the more efficient in reproducing products at the lowest cost occurs (Fig. 8-50),... 

Both shape and design details are heavily process related. The ability to mold ribs, for example, may depend on material flow during a process or on the flowability of a plastic reinforced with glass. The ability to produce hollow shapes depends on the ability to use removable cores, including air, fusible or soluble solids, and even sand. Hollow shapes can also be produced using cores that remain in the product, such as foam inserts in RTM or metal inserts in IM. 

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. 

Manufacture of highly water-absorbent polymers with uniform particle size and good flowability can be carried out by reverse phase suspension polymerization of (meth)acrylic acid monomers in a hydrocarbon solvent containing crosslinker and radical initiator. Phosphoric acid monoester or diester of alka-nole or ethoxylated alkanole is used as surfactant. A polymer with water-absorbent capacity of 78 g/g polymer can be obtained [240]. 

The physical forms indicated are those which, for each specific type of product, assure product flowability within the reported range of residual moisture they can be achieved by specific mechanical devices operating at the outlet of the evaporator and cooler. 

At the outset it is useful to consider some common examples of problems encountered in industrial mixing operations, since this will not only reveal the ubiquitous nature of the process, but will also provide an appreciation of some of the associated difficulties. Several attempts have been made to classify mixing problems and, for example, REAVELL(1) used as a criterion for mixing of powders, the flowability of the final product. HARNBY et at.(2) base their classification on the phases present that is liquid-liquid, liquid-solid and so on. This is probably the most useful description of mixing as it allows the adoption of a unified approach to the problems encountered in a range of industries. This approach is now followed here. 

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