Does oil display shear thinning properties?
Engine oil VMs are polymers with molecular weights typically in the range 300–700 k. As such they can exhibit both permanent and temporary shear thinning at the high shear rates present in engine components including the ring pack and journal bearings.
Is oil a shear thinning or thickening?
Fluids that exhibit shear thinning are sometimes called pseudoplastics and are typically complex fluids such as blood, motor oil, ketchup, and even whipped cream, though simple fluids can also exhibit the behavior near their critical point (ex: xenon in Ref. 1).
What is an example of shear thinning with polymers?
Shear thinning fluids, also known as pseudo-plastics, are ubiquitous in industrial and biological processes. Common examples include ketchup, paints and blood.
What is an example of a shear thinning fluid?
Some fluids become thinner as the rate of shear increases. These fluids are referred to as shear-thinning or thixotropic. Fluids that experience shear-thinning include: ketchup, lotions, and blood, for example. Shear stress is caused by the flow of fluid across a surface.
Why are polymers shear thinning?
In polymer systems such as polymer melts and solutions, shear thinning is caused by the disentanglement of polymer chains during flow. At rest, high molecular weight polymers are entangled and randomly oriented.
Why does shear thinning happen?
Why Does Shear Thinning Occur? Shear thinning occurs because of rearrangements in the fluid microstructure in the plane of the applied shear. It is frequently seen in dispersions such as suspensions and emulsions, including melts and solutions of polymers.
Are polymers shear thinning?
https://doi.org/10.1122/1.550409 Shear thinning is a common property of polymer melts under shear flow, in which the viscosity of a polymer fluid — the measure of a fluid’s resistance to flow — decreases with increasing shear rates, and is one fundamental characteristics that distinguishes polymeric fluids from …
What causes shear thickening?
Shear thickening behavior occurs when a colloidal suspension transitions from a stable state to a state of flocculation. A large portion of the properties of these systems are due to the surface chemistry of particles in dispersion, known as colloids.
How do you know if shear is thinning?
Shear thinning index can be calculated by dividing apparent viscosity at the lowest speed by the value of apparent viscosity at the highest speed (typically at 2 and 20 or 5 and 50 rpm). The resultant ratio is an index of shear thinning.
Is shear thinning permanent?
Permanent shear thinning increases with the number of cycles in an approximately linear fashion, although it starts to level out after 20 cycles at the highest shear rate.