Shear thinning gels

U.S. 4824590 (1989)[74] Roselle (Procter Gamble) Shear-thinning gels with incorporated air Improved stability... 

Reversible shear thinning gel— Methyl, ethyl, etc. vinyl United States 3,810,784 1974 Owens-Corning Fiberglass... 

Thixotropic formulations such systems exhibit shear thinning when agitated and thus are pumpable. Yet, when agitation stops, the system rapidly establishes a gel structure, thereby avoiding leakage. 

The typical viscous behavior for many non-Newtonian fluids (e.g., polymeric fluids, flocculated suspensions, colloids, foams, gels) is illustrated by the curves labeled structural in Figs. 3-5 and 3-6. These fluids exhibit Newtonian behavior at very low and very high shear rates, with shear thinning or pseudoplastic behavior at intermediate shear rates. In some materials this can be attributed to a reversible structure or network that forms in the rest or equilibrium state. When the material is sheared, the structure breaks down, resulting in a shear-dependent (shear thinning) behavior. Some real examples of this type of behavior are shown in Fig. 3-7. These show that structural viscosity behavior is exhibited by fluids as diverse as polymer solutions, blood, latex emulsions, and mud (sediment). Equations (i.e., models) that represent this type of behavior are described below. 

Use anionic polymers such as polyacrylic acids cross-linked with allyl ethers of pentaerythritol or sucrose as thickeners, if a gel structure and pseudoplastic (shear-thinning) properties are desirable. Consider adding colloidal alumina to further increase the viscosity at pH 13 [ 15]. 

Fernandez et al. (2007) have characterized the rheological behavior of the mashed potatoes with added biopolymers using steady shear measurements. Fresh and frozen/thawed mashed potatoes present shear thinning with yield stress (Canet et al., 2005a), and dynamic shear data reveal weak gel-like behavior in potato purees (Alvarez et al., 2004). The effects are strongly... 

Some fluids are called shear thinning. Common household examples include mayonnaise and latex paint. As they sit in a jar or can, these materials are quite viscous, almost gel-like. However, the harder we stir them, the lower their viscosities become (up to a point). Latex paint sticks to a brush or roller, but flows easily when we apply the brush or roller to a surface. Once... 

The technological importance of xanthan gum rests principally on its unusual and distinctive properties25 28 29 49,116,251,257-260 in aqueous solution. Some of these properties are (1) remarkable emulsion-stabilizing and particle-suspension ability, (2) low concentrations yield high viscosities, (3) recoverable shear-thinning (extremely large shear dependence of viscosity), (4) little variation in viscosity with temperature under normal conditions of industrial utilization, and (5) gel formation when mixed with certain other, nongelling polysaccharides. 

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