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Ceutics(2) Exam 1 - Rheology 2

Terms in this set (16)

Which viscometers are for Newtonian fluids only
Capillary
Falling Sphere
Which viscometers are for both Newtonian and Non-Newtonian
Cup & Bob
Cone & Plate
Operate good at single shearing stress
Good for Newtonian fluids only
One-Point Systems (Capillary/Falling Sphere)
Could operate at multiple shearing stress
Applicable to non-Newtonian fluids
Provide complete rheograms
Multipoint Systems (Cup & Bob/Cone & Plate)
Measures time required for the liquid to pass between two marks as it flows through a vertical capillary tube
Ostwald Capillary Viscometer
______ is an isothermal and comparatively slow recovery, on standing of a material, of a consistency lost through shearing
Thixotropy
The rheograms of thixotropic systems are highly dependent on (2)
The rate at which stress is applied or removed
The length of time the material is subjected to stress
Thixotropy is applicable to ______ systems only
Shear-thinning
At rest, thixotropy systems have a loose _____ network throughout
3D
(Thixotropy) Under shear flow starts, loose network breaks resting in a ________
Shear Thinning
(Thixotropy) Upon stress removal, the structure starts to reform, but could not instantaneously do so, as the asymmetric particles counter the forces of _________
Brownian Motion
________ suspensions do not settle out in storage, but upon shaking will aid in proper dose
Thixotropy
Altered thixotropy over time may result in inadequate _______
Formulation
_______ are clear, non-toxic, water-based gels as dermatologic base
Poloxamers
_________ have low shear rate during non-blinking, high shear rate during blinking (shear thinning)
Polymers in opthalmic
Increase in consistency on the down curve
The equilibrium is gel-like, provides great stability, yet is easily pourable
When allowed to stand, the material returns to its sol-like properties
Negative Thixotropy
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