Necessary rheological properties

The thixotropic properties of pigment structures in oil-based paints provide the paint with the necessary rheological properties. Mixing results in the destruction of the coagulation structure and allows one to apply the paint as a thin layer on the surface. Quick restoration of the coagulation structure prevents the paint from gravity-caused draining downward. 

In practice, around 30% of fracturing operations use cross-linked gels and 50% of these in turn use borates and boron compounds to cross-link the polymer and provide the necessary rheological properties. 

It is very important, from one hand, to accept a hypothesis about the material fracture properties before physical model building because general view of TF is going to change depending on mechanical model (brittle, elasto-plastic, visco-elasto-plastic, ete.) of the material. From the other hand, it is necessary to keep in mind that the material response to loads or actions is different depending on the accepted mechanical model because rheological properties of the material determine type of response in time. The most remarkable difference can be observed between brittle materials and materials with explicit plastic properties. 

One of the most common rubber adhesives are the contact adhesives. These adhesives are bonded by a diffusion process in which the adhesive is applied to both surfaces to be joined. To achieve optimum diffusion of polymer chains, two requirements are necessary (1) a high wettability of the adhesive by the smooth or rough substrate surfaces (2) adequate viscosity (in general rheological properties) of the adhesive to penetrate into the voids and roughness of the substrate surfaces. Both requirements can be easily achieved in liquid adhesives. Once the adhesive solution is applied on the surface of the substrate, spontaneous or forced evaporation of the solvent or water must be produced to obtain a dry adhesive film. In most cases, the dry-contact adhesive film contains residual solvent (about 5-10 wt%), which usually acts as a plasticizer. The time necessary... 

One of the most difficult parenteral dosage forms to formulate is a suspension. It requires a delicate balance of variables to formulate a product that is easily resuspended and can be ejected through an 18-to 21-gauge needle through its shelf life. To achieve these properties it is necessary to select and carefully maintain particle size distribution, zeta potential, and rheological properties, as well as the manufacturing steps that control wettability and surface tension. The requirements for, limitations in, and differences between the design of injectable suspensions and other suspensions have been previously summarized [17b, 18,19]. 

Rheological properties are very important in mixing and processing the compositions. Thus sedimentation of suspended solid before curing ought to be negligible. Casting must be sufficiently fluid to allow the escape of gas-bubbles. It is necessary... 

Rheology is the science of deformation and flow of matter. In food rheology, the matter of interest is food, and the importance of its deformation and flow relate to several important properties. Of these, texture is the most important. Texture is one of four quality factors of foods the others are flavor, appearance, and nutrition. In the food industry, there are other properties and processes in which rheology has an important role. They include formulation, manufacturing, transportation, and shelf stability. The measurement of the rheological properties of foods provides the food scientist and engineer with critical information necessary for the successful development and delivery of formulated foods to the consumer. 

Two Brookfield viscometers were used to collect the data necessary for rheologic property studies of wet grains a Brookfield RVDV III viscometer with a cone-and-plate spindle and a Brookfield HBDV III viscometer with a double helical ribbon impeller attachment. The Brookfield RVDV III had a full-scale torque of 7187 dyn-cm, and the HBDV III had a full-scale torque of 57,496 dyn-cm. Each viscometer had a maximum rotational speed of 250 rpm. Both viscometers had accuracy limits of 5% full-scale torque. 

On its appearance this book was given such a good welcome that a second edition proved to be necessary within four years. For this purpose the book was completely revised, updated and considerably extended. The scope of the chapters dealing with the mechanical and rheological properties was much enlarged, as where the sections discussing polymer solutions. An improved system for the assessment of the transition temperatures was introduced. SI units are used throughout the book. 

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