29 Questions
What is the meaning of the term 'Rheology'?
The science of deformation of matter under the influence of stress
What is the primary characteristic of a Newtonian liquid?
Viscosity remains constant with the applied shear force
What is the unit of viscosity equivalent to 100 centipoise?
Poise
What type of deformation is reversible?
Elastic deformation
What is the relationship between the rate of shear and shearing stress in Newtonian fluids?
The rate of shear is directly proportional to the shearing stress
What is the term for the measure of a fluid's resistance to flow upon application of a certain shear stress?
Viscosity
What is the reciprocal of viscosity?
Fluidity (Ø)
What happens to the viscosity of liquids when the temperature is increased?
It decreases
What is the equation that describes the relationship between viscosity and temperature?
η=Ae^(Ev/RT)
What is the characteristic of a plastic flow rheogram?
It intersects the shearing stress axis at a point called Yield value
What type of flow does not occur until a shearing stress corresponding to the yield value is exceeded?
Plastic flow
What is the type of flow that exhibits a decrease in viscosity with an increase in shear rate?
Pseudoplastic flow
What is the characteristic of a deflocculated suspension at rest?
Closely packed particles with minimum void volume
What is the process of accelerated reformation of the gel consistency after deformation by applying gentle or regular movements?
Reopexy
Which type of viscometer is used for measuring the viscosity of non-Newtonian fluids?
Multipoint viscometer
What is the term for the time-dependent changes in the viscosity of non-Newtonian liquids at a changeable shearing stress?
Thixotropy
What is the characteristic of a dilute suspension?
Does not show dilatancy
What is the type of viscometer that uses 20-50 ml sample?
Cup and BOB viscometer
What is the effect of high shear on polymers during preparation of products?
Results in lower viscosity
What is the effect of electrolytes at high concentration on polymer viscosity?
Competes for the absorbed water leading to polymer dehydration and decreased viscosity
What is the effect of pH on some polymers?
Causes polymer precipitation
What is the effect of temperature on polymer viscosity?
Decreases polymer viscosity, except with some polymers
What is the effect of aeration on polymer viscosity?
Increases polymer viscosity, except with emulsions
What is the effect of light on some polymers?
Causes polymer decomposition and decreased viscosity
What is the percentage of aqueous Penicillin G Procaine suspension that transforms from a fluid to a compacted depot in the muscle?
40-70 % w/w
What is affected by the viscosity of creams and lotions?
Rate of diffusion through skin
What is improved in thixotropic preparations?
Stability of vitamins
What is related to the diagnosis of diseases?
Rheology of body fluids
What is minimized or eliminated by formulation of flocculated suspensions with thixotropic characters?
Sedimentation or coagulation of suspended substances
This quiz covers the basics of rheology, including the definition of rheology, types of deformation, and viscosity. It also discusses Newtonian and non-Newtonian flow.
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