20 Questions
What is the definition of rheology?
The study of flow of liquids and deformation of matter
What phenomenon leads to the increase in viscosity by forming hydroclusters?
Hydroclustering
How is viscosity generally measured in rheological studies?
Resistance to flow
How is thixotropy defined in terms of the conversion of sol to gel?
Isothermal slow reversible
What does the hysteresis loop represent in thixotropy?
Irreversible thixotropy
Which type of deformation is reversible in a pharmaceutical system?
Elasticity
Which process involves a slow conversion from solution-fluid to semisolid gel by applying shear stress?
Thixotropy
What is the viscosity unit commonly used, as described in the text?
Poise or Centipoise
What type of flow is exhibited by polymer dispersions like Tragacanth water and Sodium alginate in water?
Pseudoplastic
In what type of flow does the resistance to flow (viscosity) increase with an increase in shear rate?
Dilatant
What does N equal to if a material exhibits Newtonian behavior?
1
What property characterizes Dilatant Flow?
Volume increases with shear rate
What is the formula to calculate the instrumental constant in the context of viscoelasticity?
(T - Tf) / V
Which type of materials exhibit both the viscous properties of liquid and the elastic property of solids, as mentioned in the text?
Creams and lotions
In the context of pharmaceutical products, what does rheology mainly study in terms of creams and ointments?
Viscosity and spreading
Why is studying rheological properties important in pharmaceutical products, according to the text?
To understand formulation and analysis
Which type of viscometers are suitable for both Newtonian and non-Newtonian systems?
Rotational viscometers
In the falling sphere viscometer formula η = t (Sb – Sf) B, what does B represent?
Constant for ball
What is the formula provided for determining viscosity in Newtonian liquids using rotational viscometers?
$\eta = C T/V$
Why are multi-point instruments preferred over single-point instruments in non-Newtonian systems?
To measure viscosity at different shear rates
Explore concepts related to viscosity, shear rate, plastic viscosity, yield value, and pseudoplastic flow. Understand the relationship between shear stress and shear rate in different materials.
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