How is thixotropic index measured?
The thixotropic index is obtained by measuring the viscosity of a fluid at room or ambient temperature. The viscometer is used to measure the viscosity at two speeds (one is a multiple or a factor of 10 of the other).
What do you mean by thixotropy fluid with example?
A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids.
What are thixotropic fluids?
A thixotropic fluid is one that takes a fixed time to return to its equilibrium viscosity when subjected to abrupt changes in shear rate. In other words, the liquid becomes less viscous (thinner or flows more easily) when shaken, stirred, agitated or otherwise stressed.
Which of the following material shows thixotropic behavior?
In its fresh state, foamed concrete is a free flowing, self-compacting and self-leveling material and therefore is expected to yield a collapse slump but it is known to exhibit a thixotropic behavior [6].
What is the thixotropic index?
The thixotropic index is a ratio of the viscosity of a material at two different shear rates (low-shear viscosity/high-shear viscosity). The low-shear rate and high-shear rate are typically different by a factor of 10.
What is the difference between pseudoplastic and thixotropic?
The key difference between thixotropic and pseudoplastic is that the viscosity of thixotropic fluids decreases upon applying a force, whereas the viscosity of pseudoplastic fluids increases upon applying a force. Some common examples of pseudoplastic fluids include ketchup, paint, cornstarch in water suspension, etc.
Which of the following is an example of thixotropic gel?
Thixotropy occurs in paint, such as lithopone in oil, which flows freely when stirred and reverts to a gel-like state on standing. Quicksand, a mixture of sand and water, is rendered thixotropic by the presence of certain clays.
What are rheopectic fluids?
Rheopectic fluids are liquids or gases whose viscosity of the fluid increases with stress over time. The behaviour of these fluids can be described as a time-dependent dilatant behaviour. Thus, these fluids are a rare class of non-Newtonian fluids.
What is an example of rheopectic fluid?
Rheopectic fluids, such as some lubricants, thicken or solidify when shaken. Examples of rheopectic fluids include gypsum pastes and printer inks. In the body synovial fluid exhibits the extraordinary property of inverse thixotropy or rheopexy.
What is thixotropic index?
The thixotropic index is a ratio of the viscosity of a material at two different shear rates (low-shear viscosity/high-shear viscosity). Thixotropy is important for applications that require the material to flow easily during dispensing but then must stay in place once they are dispensed.
Is tomato sauce thixotropic?
Ketchup is a thixotropic fluid which is classified as a non-Newtonian fluid which has property of becoming a liquid like state when force is applied and returns to gel like state without force. The thick viscous consistency of ketchup comes from the pectin in the tomato.
Which is the example of dilatant fluid?
Fluid Mechanics An example of dilatant fluid is sand in water. On the other hand, when viscosity decreases when stress increases, the fluid is called pseudoplastic fluid.
How to determine whether the sample is thixotropic?
The results give an indication whether the sample is thixotropic. Sample A has a high degree of thixotropy, so a loop is seen between the UP and DOWN curves, i.e. the samples behave differently before and after shearing. Sample B appears to have only a shear thinning nature, as the UP and DOWN curves almost overlay each other.
What is thixotropy of viscosity?
Thixotropy is the property of certain fluids and gels of becoming thinner when a constant force is applied and after reduction of the force the viscosity recovers fully to the initial state in an appropriate period of time i-ii. The higher the force that is applied, the lower the viscosity becomes.
What is thixotropic index (TI)?
Sometimes the term “Thixotropic Index (TI)” is used in different ways concerning measurement methods and analysis. Some call TI the ratio between the viscosity of a sample at a low (ƞ A) and at a high (ƞ B) rotational speeds. For example, a material’s viscosity was measured at 5 rpm (ƞ A) and at 50 rpm (ƞ B).
What is thixotropic breakdown coefficient?
The “thixotropic breakdown (Tb) coefficient” is a simple test for analyzing the time-dependent behavior of samples. It is especially used for quick quality control checks with entry-level rotational viscometers.