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The world leader in serving science The world leader in serving science
Rheological measuring systems
Seminar
Basics on Rheology
2
Content
• Overview
• Finger, Ford cup
• Capillary viscometer
• Falling ball viscometer
• Rotational viscometer
• Rotational rheometer
• Selected accessories
• Temperature control units
• Measuring geometries
• Modules
• Extensional rheometer
3
How can you measure viscosity ?
Feed back to other physical quantities, viscosity value relative or absolute. Rheometer: additional measurements of other (elastic) material characteristics
Principle Device Measured quantity
Biosensor Finger Resistance (Force,
Pressure)
Volum flow
Changel
Ford cup
(High pressure ) Capillary
viscometer
Time
Time (Pressure,
Displacement)
Falling weight (Mikro) Faling ball viscometer
Laray-viscometer Time
Torsion Torsion viscometer Damping
Compression Compression viscometer Force, Displacement
Rotation sensor Krebs-Stormer-viscometer
Rotational viscometer / - rheometer
Force, Displacement
4
Testing of Viscosity: Finger
... the cheapest viscometer
Advantages:
+ cheap
+ easy handling
+ fast
+ easy cleaning
Disadvantages:
- relative
- no reproducability
- risky → hazardous materials
5
Ford-Cup
Disadvantages:
- relative, type of cup and dye have to be
stated
e.g. DIN-cup Type A Dye Nr. 4
- no temperature control
- wrong times for non-Newtonian fluids
- not suitable for fluids with yield point
Method:
Measurement of time t (for a defined
volume), seconds as an index for the viscosity
Advantages:
+ cheap
+ easy handling /robust
+ fast
+ easy cleaning
6
Method:
The time is measured how long it takes for the fluid to pass two marks
Capillary viscometer (Gravity is the driving force)
Advantage:
+ Relatively cheap
+ Very precise for low and medium viscosities
+ Can be calibrated
+ Absolute for Newtonian fluids
Disadvantage:
- Long measuring time
- High cleaning effort
- Labor intensive (manual version)
- relative values - for Non-Newtonian fluids
- Doesn't work for samples with a yield stress
- Limited operating temperature range
7
Result:
- viscosity (kinematic) mm2 / s ] *
C4 - Capillary constant,
depends on the used capillary and has to be determined by calibration
Boundary condition: L/D > 30 (L: length, D: diameter)
Application:
Low viscous fluids
e.g. oils
Capillary viscometer (Gravity is the driving force)
C4 * t
8
Method:
The sample is pressed with a piston through the capillary. Measurement of the pressure drop p and the volume flow Q
High pressure capillary viscometer
Advantage:
+ High shear rates
+ Less friction heating because alway new sample is feeded
+ Calibration possible
+ Absolute
Disadvantage:
- High price
- For test with rod capillary three test are necessary for the Bagley-correction
- Not for low viscous materials
- Cleaning
Calculations:
p = p1 - p2
= R/(2L) * p
= 4/( R3) * Q
= R4/8L * p/ Q
Application:
Polymers
9
Method:
Measuring the falling time of a ball by measuring marks in a tube with 10° inclination
HAAKE Falling Ball Viscometer Typ C Höppler (DIN 53015 / ISO 12058)
Advantages:
+ High accuracy
+ Temperature easy to control
+ Absolute results for Newtonian liquids
+ Calibration
+ Wide viscosity range
+ Closed system
Disadvantages:
- Long measuring time
- Time consuming cleaning effort
- Labour-intensive
- Relative results for Non-Newtonian liquids
- Limited to transparent samples without yield point
- Sample density required
10
Applications:
- Low viscous fluids
e.g. oils
- Evaporating fluids / solvents
e.g. toluene
- Gases
HAAKE Falling Ball Viscometer Typ C Höppler (DIN 53015 / ISO 12058)
Result:
- Viscosity (kinematic)
K - Calibration factor for the ball,
Depends on the diameter of the ball and tube, has to be calibrated
K*( k - Fl )* t
11
Rotational Viscometer / Rheometer (relative or absolute)
Method:
Torque measurement at a given rotational
speed (CR-Method)
Deformation measurement (torque) at a
given torque (CS-Method)
Differentiation: Searle-, Couette-type
Advantages:
+Wide range of viscosity, temperature and shear rate
+Applicable for Non-Newtonian liquids and samples with yield point
+Calibration (absolute measuring systems)
Disadvantages:
- Partially cleaning intensive
(cup and rotor)
- Slightly limited accuracy
CR-Method CS-Method
Motor
Bearing
of measuring shaft
Joint
Measuring and
temperature cell
Torque-,
Deformation-
sensor
12
Method:
Rotational viscometer with sensor geometry (flow field can not be calculated)
In most cases measuring cell without temperature control
Rotational Viscometer (relative)
Advantages:
+ Easy handling
+ Quick measurement
+ Minimal cleaning effort
+ Reasonable in price
Disadvantages:
- Relative results for Non-
Newtonian liquids
- Comparable results only using
same sensor and same measuring
conditions (r.p.m., sensor)
- Faulty viscosity readings due to
variation in temperature
13
Method:
Rotational rheometer with coaxial cylinders,
Cone-Plate and Plate-Plate geometries with a calculable flow field
Rotational Rheometer (absolute)
Advantages:
+ Absolute readings, calibration
+ Modularity thanks different temperature control units, measuring geometries and accessories
+ Minimal cleaning (P/C and P/P)
+ Small sample volume (P/C and P/P)
+ Computer controlled measurement, i. e. user-independent, data documentation
Disadvantages:
- Price
- High cleaning effort (cylinder
measuring geometry)
14
Temperature control modules (TMs) for fast and accurate temperature
control over a wide temperature range
Temperature control modules (HAAKE MARS/RS 6000)
TM-PE-C (Adapter Platte) -40* (-20) 200 (180*)
Overview Temperature control modules Overview Temperature control modules
* Depending on the refrigerated circulator and bath fluid used
** When using the regarding measuring cell (e.g. pressure cell)
*** With low temperature option
Max. temp. °C Max. cooling rate K/min Max. heating rate K/min Min. temp. °C
15
Overview about Measuring Geometries
Coaxial cylinder geometries:
- acc. to DIN 53018
- acc. to ISO 3219
- Mooney/Ewart-system
- Double gap acc. to DIN 54453
Plate/Plate- and Cone/Plate
Relative measuring geometries
- Brookfield – spindles acc. to ISO 2555
- Pin- and vane rotor
- Krebs rotor
- geometries with serrated surface
- …
16
Subjective impression of the sample
Low to medium viscosity
easy to clean
High viscous, pastes,
hard to clean
Large particles
sedimentation, separation
Coaxial cylinders
in various
dimensions
Cone/plate
(without particles)
Plate/plate
(with particles)
Special sensors
vane
or
helical grooved
sensor
How to choose the measuring geometry
17
Coaxial Cylinders
Couette – Method Rotor fix, measuring cup rotates (1888, Couette) + No Taylor vortex + Drive unit and torque sensor mechanical separated + Structural disadvantages (temperature controller rotates) Searle – Methode Rotor rotates, measuring cup fix (1912, Searle). Common method for commercially available rheometers . + Structural advantages - Taylor vortexes at high rotation speed and low viscosity
18
Related to rotor surface
i = 1 / ( 2 * L * Ri2 cL) * Md = A * Md
i = 2 * Ra2 / (Ri
2 - Ra2) * 2 * n = Mk * n
Information and calculations for measuring geometries acc. to Searle method.
Coaxial Cylinders
Shear stress
(r) = Md / ( 2 * L * r2 )
Shear rate
(r) = 2 * Ri2 * Ra
2 / (Ri2 - Ra
2) / r2 *
Md – Torque [Nm]
– Angular Velocity [1/s]
= ( 2 * n ) /60
v(r) = * r
n – Rotation speed [1/min]
– Ratio of radiie
Ra / Ri
cL – Coefficient of resistance
A
Mk
.
.
19
Coaxial Cylinders acc. to DIN 53018
Application:
Samples with medium viscosities
+ High accuracy
- Cleaning efforts
- Not suitable for temperature ramps
(expansion of air bubble)
- Sample volume
- High inertia
L > 1,5 * Ri
= Ra / Ri < 1,10
LS= 3 * (Ra - Ri )
cL = 1
LS
20
Coaxiale Cylinders acc. to ISO 3219
Application:
Samples with medium up to higher viscosities
Standard geometry
+ Easy Filling
+ Suitabe for temperature rampes
- Cleaning efforts
- Sample volume
- Higher inertia
L > 3 * Ri L‘‘ = Ri
= Ra / Ri < 1,0847 = 120° + 1°
L‘ = Ri cL = 1,1
i = 1 / ( 2 * L * Ri2
* cL ) * Md
21
Coaxiale Cylinders acc. to DIN 54453
Application:
Samples with low viscosities
Measurements at higher shear rates
+ Samples volume
+ Temperature control
- Cleaning effort
- Higher inertia
L > 3 * R3
= R2 / R1 = R4 / R3 < 1,15
i = 1 / ( 2 * L * (R22 + R3
2)) * Md
i = 2 * 2 / ( 2 - 1) * 2 / 60 * n .
As special with helical
growings against
sedimentation
22
Cone/Plate measuring geometry acc. to ISO 3219
Application:
Samples with medium up to high viscosities
+ Shear rate within measuring gap is constant
+ Easy cleaning
+ Small sample volume
+ Fast and accurate temperature control
+ Low inertia
- Correct gap setting necessary
R
= 3 / ( 2 * R3 ) * Md = A * Md
= 1 / tan * 2 /( * 60) * n = Mk*n
< 4° Recommendation: = 1°
.
"Truncation"
Truncation >3 x bigger particle size
23
Plate/Plate measuring geometry acc. to DIN 53018
Application:
Samples with medium up to high viscosities
With particles
+ Easy cleaning
+ Variation of shear rate range due to variable setting
+ Small sample volume
+ Low inertia
+ As disposable geometries available
+ Temperature ramps
- Shear rate within gap not constant
R
(R) = 2 / ( * R3 ) * Md = A*Md
(R) = v / H = * R / H = 2 * R /(H * 60) * n
H << R
Mk
.
24
ThermoHaake Rheometer Measuring Range
1,0E-04
1,0E-02
1,0E+00
1,0E+02
1,0E+04
1,0E+06
1,0E+08
1,0E+10
1,E-03 1,E-02 1,E-01 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05
Shear rate (1/s)
Sh
ear
str
ess (
Pa)
1,E-04
1,E-02
1,E+00
1,E+02
1,E+04
1,E+06
1,E+08
1,E+10
Vis
co
sit
y (
mP
as)
Recommended measuring range
Cone 20 mm/1°
Cone 60 mm/1°
= 10 Pa·s
25
Double cone geometry
Application:
Samples with low up to medium viscosities
+ Evaporation blocked
+ High accuracy
+ Low sample volume
+ Easy Cleaning
- Sample temperature
- Gap setting
- Inertia higher than
standard cone /plate geometry
Double cone geometry as a quasi closed measuring cell.
26
Disposable measuring geometries
Application:
For measurements
• on samples with curring behaviour
• with high cleaning efforts
+ No cleaning necessary
+ Higher measurement rate
- Set-up measuring device
- Lower Parallelism than standard
geometry
27
Measuring geometries with serrated surface
Application:
For samples with
• Slippage effect
• Hard surface
+ Improvement of contact between
sample and measuring geometry
- Quasi absolut geometry
(reduced accuracy)
- Higher cleaning effort
28
Relative measuring geometries
Application:
Samples, which can not be measured with
a standard geometry due to:
big particles
sedimentation
…
+ Easy handling
+ Flexibiliy of design
- Relative
- Temperature control
29
Measuring Cell for Construction Materials
Application:
Rheological properties of fresh building materials
+ Easy and quick adaptation of the measurement
geometry to new materials
+ Easily adaptable serration profile
+ Vane sensors with various diameters
+ Prevention of slippage layer formation
+ Measurement in both rotational and oscillatory
mode
+ Large specimens possible
+ Robust detailing of equipment
+ Optional temperature control
- Shear rate within gap not constant
- Temperatur control
30
Measuring Cell for Bitumen
Application:
Determination of properties acc. to SHRP
Aging behaviour
Deformation behaviour
(Measurement of application behaviour at 135°C
in rotational mode)
+ Easy sample trimming in plate / plate
measuring geometrie (8, 25mm)
+ Water temperature controlled
+ Measurement in both rotational and oscillatory
mode
- Temperature range 5 up to 95°C
32
RheoScope Module
Combination of two analytical test methods:
Correlation between rheological properties
und structur
34
HAAKE MARS + Rheonaut
Simultaneous acquisition of rheological data and related FTIR spectra
Fully integrated software solution available
Spectrometer software contains
spectrum settings
Rheometer measuring job triggers
spectrometer software
Both data sets saved under same name
Rheometer data evaluation software
links to spectra data
35
HAAKE MARS + Rheonaut
Correlation of bulk properties with ongoing “Chemistry” as a function of time, temperature, shear or deformation
Constrained molecular orientation can be monitored
Combination of rheology and FT-IR ensures exact correlation of data from both methods
Reduced analysis time demand by simultaneous data acquisition
ATR (Attenuated Total Reflection)
Temperature Control: - Electrical: ambient - 400°C - Peltier: 0°C - 100°C
36
Spectrum taken after:
0 min
20 min
40 min
50 min
60 min
70 min
80 min
Auflösung: 4 cm-1 30/03/2010Probe: Technik: ATR - mit Rheo Anzahl Scans: 8
21002150220022502300235024002450
Wavenumber cm-1
0.0
0.1
0.2
0.3
0.4
0.5
Ab
so
rba
nce
Un
its
Auflösung: 4 cm-1 30/03/2010Probe: Technik: ATR - mit Rheo Anzahl Scans: 8
14501500155016001650170017501800
Wavenumber cm-1
0.0
0.1
0.2
0.3
0.4
0.5
Ab
so
rba
nce
Un
its
Auflösung: 4 cm-1 30/03/2010Probe: Technik: ATR - mit Rheo Anzahl Scans: 8
500100015002000250030003500
Wavenumber cm-1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Ab
so
rba
nce
Un
its
≀≀
PUR Foam Curing Monitored via FT-IR
NCO stretching decreasing
C=O/ urethane (non-bonded) stable
HNCO (Amide II) combined motion increasing
37
PUR Foam in Oscillatory Shear + FT-IR
Rheology clear
function of ongoing
chemistry
Increase of G’
function of amide bond
concentration
Increase of G’’
function of air bubble
concentration
“Quick” Reaction as
free Urethane stays at
constant level
0,1
0,15
0,2
0,25
0,3
0,35
0,4
0,45
0,5
0,55
0,6
Time/min
Ab
so
rpti
on
Un
its
1,00E+02
1,00E+03
1,00E+04
1,00E+05
1,00E+06
G', G
''/P
a
Isocyanate Intensity @ 2260 cm-1
Amide II Intensity @ 1510 cm-1
Urethane Intensity @ 1725 cm-1
G'
G''
0 80
38
HAAKE CaBER 1 (Capillary Breakup Extensional Rheometer)
Sample
Laser-
micrometer
• Extensional flows occur in many industrial processes
and applications and influence these processes often to a great extent.
• As a consequence the knowledge of extensional properties is important.
• Extensional properties can not be measured with rotational rheometers.
[Click Image to repeat animation.
39
Overwiew Product Line Laboratory Instruments
Falling Ball Viscometer HAAKE Falling Ball Viscometer Type C Höppler
Extensional rheometer HAAKE CaBER 1 H
AA
KE
C
aB
ER
S
oft
wa
re
Rotational viskosimeters and rheometers HAAKE Viscotester 1 plus, 2 plus
HAAKE Viscotester C, D, E acc. to ISO 2555
HAAKE Viscotester 550
HAAKE RotoVisco 1
HAAKE RheoStress 1
HAAKE RheoStress 6000
HAAKE MARS III HA
AK
E R
he
oW
in
Pa
rt 1
1
IQ/O
Q
TT
S
MW
D
Sp
ec
tra
In
terf
ac
ial S
eri
es
1