Term
| Which of the following have flow properties:solid,liquid,or gas? |
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Definition
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Term
| What represents the internal friction of a system and is the resistance to flow? |
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Definition
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Term
| What determines the system viscosity? |
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Definition
| The strength that a layer exerts on adjacent layers. |
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Term
| Which type of fluids have a linear relationship between rate of shear and shearing stress? |
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Definition
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Term
| What is the Newtonian law of flow? |
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Definition
| The higher the viscosity, the greater the shearing stress required to produce a certain rate of shear. |
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Term
| How do you calculate rate of shear? |
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Definition
G=dv/dr
G-rate of shear
dv-thickness of layers
dr-difference of velocity |
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Term
| How do you calculate shearing stress given the force? |
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Definition
F=force/A
F-shearing stress
A-area |
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Term
| Calculate shearing stress or rate of shear given the other. |
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Definition
F=nG
F-Shearing stress
n-coefficient of viscosity(poise)
G-Rate of shear |
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Term
| The greater the force the ______ the rate of shear. |
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Definition
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Term
| What are the three non-Newtonian flows? |
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Definition
Plastic flow
pseudo-plastic flow
dilatant flow |
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Term
| What is the relationship between viscosity and fluidity? |
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Definition
Fluidity is the reciprocal of viscosity
1/n |
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Term
| How do you calculate kinematic viscosity? |
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Definition
viscosity(n)/density(p)
units are stokes or centistokes depending on poise or cp |
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Term
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Definition
| The force required to move adjacent layers 1cm apart at 1cm/s velocity. |
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Term
| Differentiate plasic and elastic. |
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Definition
plastic=flexible
elastic=rigid |
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Term
| What does a Newtonian rheogram look like? |
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Definition
| a linear line going through the origin |
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Term
| What does a Platsic flow rheogram look like? |
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Definition
curved at the bottom but linear going up.
-intersects x-axis at yield value(f) |
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Term
| What does a pseudoplastic flow rheogram look like? |
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Definition
curve increasing in slope
.
.
..
... |
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Term
| What does a Dilatant flow rheogram look like? |
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Definition
curve decreasing in slop
...
..
.
. |
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Term
What do plastic flow compounds act as if:
1)F2)F>f
F=shearing stress
f=yield value |
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Definition
1)elastic(solid)
2)Newtonian |
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Term
| What kind of flow are characterized by bingham bodies? |
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Definition
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Term
| How do you calculate plastic viscosity? |
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Definition
plastic viscosity(U)=(F-f)/G
units are still poise |
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Term
| What are flocculated suspensions an example of? |
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Definition
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Term
| The more flocculated the suspension, the _______ the yield value is. |
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Definition
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Term
| What contributes to yield value? |
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Definition
van der waals forces
inter-particle friction |
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Term
| What flow is in between Newtonian and plastic? |
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Definition
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Term
| What flow represents shear thinning systems? |
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Definition
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Term
| What is apparent viscosity? |
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Definition
| viscosity at a given F that is determined by the slope of the tangent. |
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Term
Natural and synthetic gums are an example of which material?
ex-tragacanth, methylcellulose, Na-CMC, Na-alginate |
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Definition
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Term
| With increasing force in pseudo-plastic materials, uncoiling cause the viscosity to _______. |
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Definition
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Term
| Which flow is opposite to pseudo-plastic and viscosity increases with force? |
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Definition
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Term
What is the flow, looking at F^N=nG
1)F=1
2)F>1
3)F<1 |
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Definition
1)newtonian
2)pseudoplastic
3)dilatant |
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Term
| Which system is shear thickening? |
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Definition
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Term
| Which system is characteristic of suspensions(>50% solids) with small deflocculated particles ? |
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Definition
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Term
| Are dilatants closed packing or open dilated with increasing rates of shear? |
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Definition
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Term
| What are the two one point viscometers and which type of fluid can they measure? |
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Definition
- Capillary and Falling Shpere
- Newtonian fluids only |
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Term
| What are the two multipoint viscometers and which fluids do they measure? |
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Definition
-Cub&Bob and Cone&Plate
-Newtonian and Nonnewtonian |
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Term
| Differentiate one point and multipoint viscometers. |
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Definition
-One-point systems operate at only at a single shearing stress(F) and give only one force of shear(G)
-Multi-point work at multiple shearing stresses (F) and provide complete rheograms |
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Term
Give the relating names to each
1)Capillary Viscometer
2)Falling ball viscometer
3)Cup&Bob viscometer
4)Cone&plate viscometer |
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Definition
1)Ostwald
2)Hoeppler
3)Rotovisco
4)Brookfield |
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Term
| Describe the Capillary Viscometer |
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Definition
Measures the time for a liquid to pass between two marks as it goes down a capillary tube. Then its compared to water to obtain relative viscosity.
use n1/p1t1=n2/p2t2 |
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Term
| Describe the Falling ball viscometer |
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Definition
the rate the ball falls is an inverse function of the viscosity.
n=t(Sb-Sf)B
B=factor provided by manufacturer |
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Term
| Describe the Cup&Bob viscometer |
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Definition
| sample is sheared between cup and bob. rotation causes torque which is proportional to the viscosity of the sample |
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Term
| What is the disadvantage of a cup&bob viscometer called "plug flow"? |
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Definition
| shearing stress decreases with the distance away from bob so use as big of a bob as possible |
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Term
| Differentiate Couette type and Searle type rotations. |
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Definition
Couette type is cup rotation
Searle type is bob rotation. |
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Term
| Describe cone and plate viscometer. |
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Definition
the sample is sheared at the gap between cone and plate.
n=CT/V
C-instrumental constant
T-shearing stress(read off scale)
V-rate of shear |
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Term
| What happens when shearing stress is removed from Newtonian system? |
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Definition
| rate of shear decreases exactly as it increases. linearly |
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Term
| What happens when shearing stress is removed from plastic systems? |
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Definition
| rate of shear decreases (in a linear fashion) slower than it increases. (shifts left) |
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Term
| What happens when shearing stress is removed from pseudo-plastic systems? |
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Definition
| rate of shear decreases (in a curved fashion) slower than it increases. slow recovery |
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Term
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Definition
| an isothermal and comparatively slow recovery of consistency lost through shearing |
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Term
| What are rheograms of thixotropic systems dependent on? |
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Definition
| rate at which stress is applied and released and the length of time of the stress |
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Term
| What kind of system and flow is thixotropy applicable to? |
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Definition
pseudoplastic flow
shear-thinning systems only |
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Term
| What are thixotropic systems like at rest? |
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Definition
| a loose 3D network resembling a gel |
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Term
| What are thixotropic systems like under shear flow? |
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Definition
| loose network breaks resulting in shear thinning and gel to solution transformation |
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Term
| Once stress is removed, do thixotropic systems recover instantaneously? |
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Definition
| no asymetric particles have to overcome brownian motion. |
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Term
| What is negative thixotropy? |
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Definition
| upon stress, viscosity increases rather than decrease |
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Term
| What kind of flow is associated with negative thixotropy? |
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Definition
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Term
| When a negative thixotropic material is left sitting is the material sol-like or gel-like? |
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Definition
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Term
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Definition
| a material that increases viscosity at a much faster rate when under shear than when allowed to rest. |
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Term
| What does rheopexy apply to? |
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Definition
| Dilatant flow and shear thickening systems |
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Term
| How do you measure thixotropy? |
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Definition
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Term
| How are hysteresis loops used to measure thixoptropy? |
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Definition
1)determining structural breakdown with time at a constant rate of shear
OR
2)determining structural breakdown due to increasing rate of shear |
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Term
| Why is thixotropy desirable? |
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Definition
it keeps a high container consistency for suspensions(etc) and yet pour and spread easily when needed.
-also good for I.M slow release yet easy to inject |
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Term
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Definition
aka Pluronics (clear/nontoxic/waterbase gels)
--sol at low temp/conc(newtonian)
--non-newtonian at high temp/conc
Ex-aloevera gel, plural??? |
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Term
| What kind of system do you want in opthalmic solutions? |
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Definition
| shear thinning so that when you blink it keeps at high shear rate |
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Term
| Does viscosity increase or decrease with increasing temperature? |
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Definition
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Term
| What is the equation used to solve for activation energy? |
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Definition
ln(n)=ln(A)+(Ev/R)*(1/T)
n=viscosity
A=constant depending on MW
Ev=Activation energy
T=kelvin
R=8.314 J/mol*k |
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Term
| How do you find activation energy given the temperatures and viscosity? |
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Definition
1)convert temp to kelvin and take inverse
2)plot ln(n) vs 1/T
3)Find equation of line ln(n)=###### + ####x
4) the ##### in front of x= Ev/R
5)divide number by R
*units in example were cal/mol |
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Term
| Liquid property is to viscosity as solid property is to what? |
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Definition
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Term
| Liquid property is to Newton as solid property is to who? |
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Definition
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Term
| Liquid property is to Newton as solid property is to who? |
|
Definition
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Term
|
Definition
E=F/y
elasticity=stress/strain |
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Term
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Definition
| the possession of both viscous properties of liquids and elastic properties of solids |
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Term
| What do viscoelasticity measurements test? |
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Definition
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Term
Match quantifiable properties with these psychorheologic properties.
1)body
2)slip
3)spreadability
4)feel
5)sensory satisfaction |
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Definition
1)viscosity
2)yield value
3)thixotropy
4)kinematic viscosity
5)viscoelasticity |
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