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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

31

Other special measuring cells

32

RheoScope Module

Combination of two analytical test methods:

Correlation between rheological properties

und structur

33

HAAKE MARS + RheoScope Module

Example:

Polyethylene

Rheological Data

Images

Click: Video

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

40

Thank you for your attention

Any questions ?