Here are the answers to the Frequently Asked Question(FAQS) on Rheology.

How is temperature related to viscosity?

Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another. Thus the viscosity of a liquid depends on the: … the kinetic energy of the molecules, which depend on the temperature.

Does the viscosity of water change with temperature?

The viscosity of water decreases markedly with increasing temperature. When the viscosity decreases, the flow resistance decreases. … Yes, liquids viscosity decreases by increasing in temperature as through these molecules of liquids went into excited take and cause the increase in kinetic molecular energy.

Why does viscosity change with temperature?

With an increase in temperature, there is typically an increase in the molecular interchange as molecules move faster in higher temperatures. The gas viscosity willing crease with temperature. With high temperatures, viscosity increases in gases and decreases in liquids, the drag force will do the same.

What is isoelectric point?

The isoelectric point is the pH at which a particular molecule carries no net electrical charge or is electrically neutral in the statistical mean.

The standard nomenclature to represent the isoelectric point is pH(I).

What are Newtonian and non-Newtonian fluids?

A Newtonian fluid is a fluid in which the viscous stresses arising from its flow, at every point, are linearly proportional to the local strain rate—the rate of change of its deformation over time. Water, oil, gasoline, alcohol and even glycerin are examples of Newtonian fluids.

A non-Newtonian fluid is a fluid that does not follow Newton’s law of viscosity, i.e. constant viscosity independent of stress. Most commonly, the viscosity (the gradual deformation by shear or tensile stresses) of non-Newtonian fluids is dependent on shear rate or shear rate history.

Non-Newtonian fluids are slurries, suspensions, gels and colloids.

Blood is a non-Newtonian fluid. Its viscosity changes depending on how much stress is placed on it. It’s a so-called “shear-thinning” liquid–the more blood is agitated the less viscous it becomes.

Honey is a non-Newtonian fluid – a fluid that changes its behavior when under stress or strain.

The yogurt has a characteristic of non-Newtonian fluids that shows different viscosity when a different shear rate is provided.

Ketchup, in addition to being an exceptionally popular condiment, is also a non-Newtonian fluid.

Jelly is also a non-Newtonian fluid. It is a ‘colloid’ and it is closest to a liquid rather than a solid.

Aqueous solution of Guar Gum is a non-Newtonian fluid.

The viscous colloidal solutions of Guar Gum show the typical variance of viscosity versus shear rate of non-Newtonian fluids.

Best way to make aqueous solution of Polysaccharides.

Polysaccharides start to swell in contact with water. If you are not fast or cautious enough lumps get created.

The best way to make use of the polysaccharides to take part in the aqueous medium is to wet it initially with glycerin or oil (If oil is part of your formulation, like emulsion, than dissolve it in the oil phase) and then put water over it. A globule-free colloidal solution of the polysaccharide will form.

Units of Measurement of viscosity.

The UoM of viscosity in different systems are:

Sl. No. System UoM Abbreviation
01 SI Pascal-second Pa. S
centipoises cPs
02 CGS square centimeters per second cm2 s–1
centistokes cSt