RHEOLOGY Flashcards
1
Q
RHEOLOGY
came from the greek word
A
rheo & logos
2
Q
RHEOLOGY
rheo means
A
to flow
3
Q
RHEOLOGY
logos means
A
science
4
Q
the study of deformation and flow properties of matter
A
rheology
5
Q
RHEOLOGY
deformation is for
A
solids
6
Q
RHEOLOGY
flow properties is for
A
liquids
7
Q
RHEOLOGY
main components
A
viscosity
elasticity
8
Q
RHEOLOGY | MAIN COMPONENTS
- resistance to flow
- property of liquids
A
viscosity
9
Q
RHEOLOGY | MAIN COMPONENTS
- stickiness or structure
- property of solids
A
elasticity
10
Q
PROPONENTS OF RHEOLOGY
coined/suggested the term rheology
A
bingham & crawford
11
Q
PROPONENTS OF RHEOLOGY
true theory of elasticity
A
robert hooke
12
Q
PROPONENTS OF RHEOLOGY
Robert hooke true theory of elasticity
A
Hooke’s Law of Solids
13
Q
PROPONENTS OF RHEOLOGY
the resistance which arises lack of slipperiness of the parts of liquid is proportional to the velocity with which parts of the liquid are separated from one another
A
principia
14
Q
PROPONENTS OF RHEOLOGY
principia
A
Isaac Newton
15
Q
PROPONENTS OF RHEOLOGY
Isaac Newton’s Law
A
Law of liquids
16
Q
PROPONENTS OF RHEOLOGY
liquids automatically flow
A
Newton’s law of liquids
17
Q
CONCEPTS IN RHEOLOGY
the ____ of the material dictates the observed physical response
A
chemical nature
18
Q
CONCEPTS IN RHEOLOGY
the chemical nature of the material dictates the observed ____
A
physical response
19
Q
CONCEPTS IN RHEOLOGY
the ____ after applying force is linked to the timescale of the microstructural motion from thermal or mechanical energy
A
material’s structure
20
Q
CONCEPTS IN RHEOLOGY
the material’s structure after applying force is linked to the ____ from thermal or mechanical energy
A
timescale of the microstructural motion
21
Q
- the higher the viscosity of the liquid, the **greater the force per unit area (shearing stress**) required to produce a specific shear rate
- viscosity is independent on the rate of shear (G)
- ex: simple liquids, either pure chemicals or solutions, water
A
NEWTON’S LAW OF FLOW
22
Q
NEWTON’S LAW OF FLOW
relationship of viscosity and force per unit area (shearing stress) required to produce a specific shear rate
A
directly proportional
higher viscosity, greater shearing stress
23
Q
NEWTON’S LAW OF FLOW
viscosity is ____ on the rate of shear (G)
A
independent
24
Q
NEWTON’S LAW OF FLOW
the higher the viscosity of the liquid, the greater the force per unit area (shearing stress) required to produce a ____
A
specific shear rate
25
* **absolute viscosity** **divided by the** **density** of the liquid at a specific temperature
* units: **stokes (s)** or **centistokes (cs)**
* arbitrary scales: **Saybolt**, **Redwood**, **Engler**, etc.
kinematic viscosity
26
# **KINEMATIC VISCOSITY**
**graphical presentation** of rheology
rheogram
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# **KINEMATIC VISCOSITY**
**relationship** between **rate of shear** and **shear stress**
directly proportional
28
# **KINEMATIC VISCOSITY**
units
stokes (s)
centistokes (cs)
29
# **TEMPERATURE DEPENDENCE OF VISCOSITY**
for **liquids**
**high** temp, **low** viscosity
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# **TEMPERATURE DEPENDENCE OF VISCOSITY**
for **gases**
**high** temp, **high** viscosity
31
# **TEMPERATURE DEPENDENCE OF VISCOSITY**
**reciprocal** of viscosity
fluidity
32
# **TEMPERATURE DEPENDENCE OF VISCOSITY**
the **fluidity** ____ with **temperature**
increase
33
* majority of fluid pharmaceutical products **do not follow Newton's law of flow** (**without** shear stress)
* generally exhibited by:
- **colloids**
- **emulsions**
- **suspensions**
- **ointments**
non-newtonian systems
34
# **NON-NEWTONIAN SYSTEMS**
**majority** of fluid pharmaceutical products ____ **Newton's law of flow**
do not follow
35
# **NON-NEWTONIAN SYSTEMS**
generally exhibited by
colloids
emulsions
suspensions
ointments
36
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS**
* **does not begin to flow** until a **shearing stress** corresponding to the **yield value** is **exceeded**
* **Bingham bodies**
* exhibited by **concentrated flocculated suspension**, and **semisolid dosage forms**
| e.g. **TOOTHPASTE**
PLASTIC FLOW
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# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PLASTIC FLOW**
**does not begin to flow until a shearing stress** corresponding to the ____ is **exceeded**
yield value
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# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PLASTIC FLOW**
also known as
BINGHAM BODIES
39
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PLASTIC FLOW**
**exhibited** by **concentrated** ____ and ____
flocculates suspensions & semisolid dosage forms
40
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS**
* the **viscosity** of a susbtance **decreases** with **increasing rate of shear**
* **shear thinning system**
* exhibited by many pharmaceutical products, e.g. **liquid dispersions of natural & synthetic gums**
| e.g. **PAINT**
PSEUDOPLASTIC FLOW
41
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PSEUDOPLASTIC FLOW**
the **viscosity** of a substance ____ with **increasing rate of shear**
decreases
42
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PSEUDOPLASTIC FLOW**
also known as
shear thinning system
43
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | PSEUDOPLASTIC FLOW**
**exhibited** by many pharmaceutical products like **liquid dispersions** of ____ and ____
natural and synthetic gums
44
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS**
* the **viscosity** of a substance **increases** with **increasing rate of shear**
* as **shear stress** is **increased**, the **bulk** of the system **expands**
* **shear thickening system**
* exhibited by **highly concentrated deflocculated suspensions**
| e.g. **CORNSTARCH** (**OBLEEK**)
DILATANT FLOW
45
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | DILATANT FLOW**
the **viscosity** of a substance ____ with **increasing rates of shear**
increases
46
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | DILATANT FLOW**
as **shear stress** is **increased**, the **bulk** of the system ____
expands
47
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | DILATANT FLOW**
also known as
shear thickening system
48
# **TIME-INDEPENDENT NON-NEWTONIAN FLUIDS | DILATANT FLOW**
exhbited by **highly concentrated** ____
deflocculated suspensions
49
* with shear thinning systems, the **structure breakdown does not reform immediatley when stress is reduced** or **removed**
* applicable only to **shear thinning systems**
* **thixotropy**
time dependent non-newtonian fluids
50
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
with shear thinning systems, the **structure breakdown** ____ when **stress** is **reduced** or **removed**
does not reform immediately
51
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
an **isothermal** and comparatively **slow recovery** on standing of a material of a **consistency lost through shearing**
thixotropy
52
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
is **applicable only** to
shear thinning systems
53
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
Gel-**Sol**-Gel
**slow** process
thixotropy
54
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
**thixotropy** is a ____ process
slow
55
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
Gel-**Sol**-Gel
**fast** process, mild turbulence
rheopexy
56
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
**rheopexy** is a ____ process
fast
57
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
Sol-**Gel**-Sol
**slow** process
**negative** thixotropy
58
# **TIME DEPENDENT NON-NEWTONIAN FLUIDS**
Sol-**Gel**-Sol
**fast** process, mild turbulence
**negative** rheopexy
59
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
**Newtonian** liquids (**single** shear rate)
**Capillary** viscometer
**Falling sphere** viscometer
60
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
**Newtonian** & **Non-Newtonian** liquids (**multipoint**, **rotational**)
**Cup & Bob** viscometer
**Cone & Plate** viscometer
61
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
* aka **Ostwald viscometer**
* the **viscosity** of a **newtonian** liquid can be determined by measuring the **time required for the liquid to pass between two marks** as it **flows by gravity** through a **vertical capillary tube**
* principle is **time-dependent**
CAPILLARY VISCOMETER
62
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
**Capillary** viscometer is also called as
Ostwald viscometer
63
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
* aka **Hoeppler** viscometer
* a **glass** or **steel ball rolls down** an **almost vertical glass tube** containing the test liquid at a known constant temperature
* the **rate** at which a **ball of a particular density** and **diameter** **falls** is an **inverse function** of the **viscosity** of the sample
* time-**dependent**
FALLING SPHERE VISCOMETER
64
# **DETERMINATION OF RHEOLOGIC PROPERTIES**
**Falling Sphere** viscometer is also called as
Hoeppler viscometer
65
# **DETERMINATION OF RHEOLOGIC PROPERTIES | FALLING SPHERE VISCOMETER**
a **glass** or **steel ball rolls down** an ____ containing the test liquid at a known constant temperature
almost vertical glass tube
66
# **DETERMINATION OF RHEOLOGIC PROPERTIES | FALLING SPHERE VISCOMETER**
the **rate** at which a **ball** of a **particular density** and **diameter falls** is an ____ of the **viscosity** of the sample
inverse function
67
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN**
* the sample is **sheared** in the **space between** the **outer** wall of a **bob** and the **inner** wall of a **cup** into which the bob fits
* **Couette type** - MacMichael Viscometer
* **Searle type** - Brookfield and Stormer Viscometer
Cup and Bob Viscometer
68
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CUP & BOB**
the sample is **sheared **in the **space between** the ____ of a **bob** and the ____ of a **cup** nto which the bob fits
**outer** wall of a **bob**
**inner** wall of a **cup**
69
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CUP & BOB**
* **Couette** type
* Rotating **cup**
MacMichael viscometer
70
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CUP & BOB**
* **Searle** type
* Rotating **bob**
Brookfield & Stormer Viscometer
71
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | BROOKEFIELD**
in the **Brookefield viscometer**, the generally acceptable **%torque** is
≥ 10%
72
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN**
* aka **Ferranti-Shirley** viscometer
* the sample is **placed** at the **center of the plate**, which is then **raised into position under the cone**
* a **variable-speed motor** drives the cone, and the sample is **sheared** in the **narrow gap between** the **stationary plate** and the **rotating cone**
* **plate** is **mobile**
CONE & PLATE VISCOMETER
73
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CONE & PLATE**
**Cone & Plate** viscometer is also called as
Ferranti-Shirley viscometer
74
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CONE & PLATE**
the sample is **placed** at the ____
center of the plate
75
# **DETERMINATION OF RHEOLOGIC PROPERTIES | NON-NEWTONIAN | CONE & PLATE**
a ____ **drives** the **cone**
variable-speed motor
76
* based on **mechanical properties** of the material that **exhibit both viscous** properties of liquids and **elastic** properties of solids
* can **behave predominantly** as **viscous** or **predominantly** as **elastic**, or **equal**, depending on the magnitude and the time scale of the applied shear stress
* examples: **creams**, **lotions**, **ointments**, **suppositories**, **suspensions**, **colloids**
* example: **blood**, **sputum**, **cervical fluid**
VISCOELASTICITY
77
# **VISCOELASTICITY**
based on mechanical properties of material that exhibit ____
both viscous & elastic properties
78
# **VISCOELASTICITY**
can behave ____
predominantly viscous or elastic
79
* study of how we **perceive** the **textural characteristics** of materials
* **relationship** between **instrumental** data and **sensory** data
- **mouth-feel warmness** and **richness for food**
- **smoothness**, **slimyness**, **stickiness** or **stinginess** for **cosmetics**
PSYCHORHEOLOGY
80
# **PSYCHORHEOLOGY**
study of how we **perceive** the ____ of materials
textural characetristics
81
# **PSYCHORHEOLOGY**
relationship between ____ and ____
instrumental & sensory data
