… and other liquids.
Shear Thinning Liquids
- When you try to pour ketchup, sometimes it just won’t start until you tap the bottle on the side of the bottom.
- This is because when force is applied, the liquid becomes thinner, and flows more easily.
- Other similar liquids are mayonnaise, oyster sauce, mustard, hoisin.
- GEEK INFORMATION:
Summary: Warm ketchup flows more easily than cold ketchup.Non-Newtonian viscous shear thinning in ionic liquids We have studied the shear thinning of several protic and aprotic ionic liquids (ILs) by stress-controlled rheometry, which indicated that some ILs exist as liquid phase aggregates that can be disrupted or broken at high shear rates. Increasing the temperature shifted the onset of shear thinning to higher frequency and indicated that a smaller or less cohesive aggregate was formed. However, upon application of a sufficiently high temperature, the sample resumed the characteristics of a Newtonian fluid. (HOEt)2NH.AcOH was selected as an example of a protic ionic liquid (PIL) to probe concentration effects on liquid ordering. At water concentrations lower than one equivalent per PIL component pair, the viscosity rapidly decreased, although the onset frequency of shear thinning remained constant. The shear thinning and low viscosity regime remained until approximately 3–4 equivalents of water were added and the PIL behaved as a Newtonian fluid. The effect of water on the shear thinning of (HOEt)2NH.AcOH indicated that small dilution volumes did not alter the aggregate structure, but instead reduced the number of aggregates. Both the temperature and additive water strongly suggested that the IL aggregates were due to intermolecular hydrogen bond networks.
Shear Thickening Liquids
- When you mix water and corn starch (as a thickener in gravy for example) it flows easily.
- If you had a large amount and smacked it with your hand, it would feel quite solid.
- This is because when force is applied, the liquid becomes thicker, and flows less easily.
- Other similar liquids are
- GEEK INFORMATION:
Shear induced self-thickening in chitosan-grafted polyacrylamide aqueous solution A remarkable shear induced self-thickening of chitosan-graft-polyacrylamide aqueous solution was observed. After the polyelectrolyte solution presenting shear thinning was subjected to a high-rate shear for several minutes, their viscosities recovered and then a much higher zero shear viscosity than the original one appeared. Obviously, the self-thickening differs from conventional shear thickening or viscous recovery, as reported previously. The mechanism of self-thickening was investigated by rheological methods together with TEM, 1H NMR and DLS, etc. It was found that some aggregates exist in original chitosan-graft-polyacrylamide aqueous solution and the scale of such aggregations would become larger within several minutes after a strong shear. The thickening was proven to be the result of an enhanced scale of GPAM aggregation in aqueous solution, and the mechanism of aggregation was proven to be intermolecular hydrogen bonding effects. Besides, the shear-induced self-thickening appears to be facile, maintainable and easily controllable by changing the shear conditions.
Rheology of Liquid Foods
Liquid foods are classified and their properties discussed under various types of rheological behavior: Newtonian, pseudoplastic, shear thickening, thixotropic, and viscoelastic. Rheological data on selected liquid foods are summarized in either tabular form or in the form of equations. Wherever possible the influence of temperature, constituents, and structure on the rheological behavior is detailed. Because many foods are suspensions, the measurement of flow properties of suspensions and factors influencing their rheological behavior are also covered. Finally, the relationship between the flow behavior and the sensory evaluation of mouth feel and viscosity is discussed.
