flow properties of filled materials and standards...

Flow Properties of Filled Materials and Standards Update

Martin Rides 25 October 2006

H4 - Flow properties of filled materials (2005-08)U4: Dynamic properties of solid/liquid materials systems at the nano

and micro-scale (2005-08)

2

Outline

• Introduction• Update on intercomparison on slip flow

measurements – final results• Characterisation of filled materials• Piezoelectric devices for rheological

measurements• Rheological standards in ISO• Summary / future work

3

Background

The flow behaviour of multi-phase/highly filled materials can be complex

Multi-phase materials exhibit flow behaviours that are difficult to characterise, but are often essential to their processability, e.g.:– extreme shear thinning (e.g. thixo-casting)– slip (e.g. plastics extrusion)

The reliable measurement of the flow behaviour of multi-phase is relevant to many industrial sectors and is important to, for example: – materials design, selection, quality control (mix quality)– process modelling (design, optimisation)– reducing scrap rates and time to market

4

H4: Flow properties of filled materials

Project objectives:• development of new/improved measurement methods/procedures for monitoring flow properties of filled materials, with particular emphasis on mixing/compounding processes (mix quality)

RAPRA – supply of nano-composite samples / mix quality

• evaluation of the use and capability of innovative piezoelectric devices, to facilitate rheological measurement and improved process monitoring

• development of the Melt Flow Rate method for moisture sensitive materials (e.g. PET, PBT, nylon) to avoid the need for solvent-based testing

• development of Melt Flow Rate precision and uncertainty statementsin support of ISO standardisation activities, through intercomparison

5

0

10

20

30

40

50

60

0 50 100 150 200 250Time

Ext

rusi

on p

ress

ure,

MP

a

Ps, Ros248, H005Pl, Ros248, H005

No extrudate distortion

Piston head

Piston

Pressuretransducer

Capillary die

Heater

Barrel wall

Sample

Entrance pressure drop

Shear flow pressure drop

Stagnant / vortexregion

Piston head

Piston

Pressuretransducer

Capillary die

Heater

Barrel wall

Sample

Entrance pressure drop

Shear flow pressure drop

Stagnant / vortexregion

Entrance pressure drop of filled polymer using different diameter dies at 165 °C (H005)

6

Different flow regimes and die diameters indicating a die dependence of results above the slip transition.

AAEHH005 at 165 °CFilled EVA

100000

1000000

1 10 100 1000 10000 100000

Apparent shear rate, 1/s

She

ar s

tress

, Pa

0.5mm

1mm

1.5mm

2mm

7

Constant shear stress data to determine slip velocity


y = 500x + 2000

y = 693.46x + 501.54

y = 532.04x + 375.96

y = 366.37x + 263.23

y = 278.36x + 196.75

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 1 2 3 4 51/(die radius, mm)

App

aren

t she

ar ra

te, 1

/s

325 kPa350 kPa400 kPa450 kPa500 kPaLinear (500 kPa)Linear (450 kPa)Linear (400 kPa)Linear (350 kPa)Linear (325 kPa)

Shear stress

8

Intercomparison results for wall slip velocity


10

100

1000

100 1000Shear stress, kPa

Wal

l slip

vel

ocity

, mm

/s

.

Lab ALab BLab CLab D

9


AAEHH002 at 220 °Ccarbon black filled HDPE

1

10

100

1000


Slip

vel

ocity

, mm

/s

Lab Alab BLab CLab D

+/- 40%

10

Uncertainties in slip velocityMeasurement Good Practice Guide No. 90 Using at least three dies

EVA AAEHH005 at 165 °C.

Shear stress, kPa 1/R 325 400 450 325 400

1 500 940 - 500 940

1.333333 500 950 1350 500 -

2 806 1572 1990 806 1572

4 1300 2475 3250 - 2475

Maximum radius ratio 4 4 3 2 4

95% confidence range on gradient value 118 254 838 1443 657

Relative expanded uncertainty of slip velocity (95% conf. level), % 42% 48% 121% 440% 131%

2

22

2

11

2

22

2

11

)(.)(.)(.)(. )(

∂∂

+

∂∂

+

∂∂

+

∂∂

= RuRV

RuRV

QuQV

QuQV

Vu ssT

T

sT

T

ssc

11


10

100

1000


Wal

l slip

vel

ocity

, mm

/s

.



+/- 40% tolerance bars

12


AAEHH002 at 220 °CCarbon black filled HDPE

+/- 40% tolerance bars

1

10

100

1000


Slip

vel

ocity

, mm

/s


+/- 40%

13

Intercomparison –paper in preparation

Results of an intercomparison of slip flow velocity measurements of filled polymers by capillary extrusion rheometry

by

M Rides*&, C Allen*, D Fleming+, B Haworth$, A Kelly#

*National Physical Laboratory+ Fleming Polymer Testing & Consultancy

$ IPTME, Loughborough University# IRC in Polymer Science and Technology, University of Bradford

14

Polymer flow incorporating slip and implications for polymer processing simulation (DEPC-MN 40)

M. Rides, D. Fleming and C.R.G. Allen

y = 2E-22x4.2399

R2 = 0.999

10

100

1000

100000 1000000

Corrected shear stress, Pa

Wal

l slip

vel

ocity

, mm

/s

Scaled radial position

Vel

ocity

, mm

/s

0 10.2 0.4 0.6 0.80

10

20

30

40

50


Vel

ocity

, mm

/s

0 10.2 0.4 0.6 0.80

10

20

30

40

50


Vel

ocity

, mm

/s

0 10.2 0.4 0.6 0.80

10

20

30

40

50


Vel

ocity

, mm

/s

0 10.2 0.4 0.6 0.80

10

20

30

40

50

100000

1000000

10 100 1000 10000Apparent shear rate, 1/s

She

ar s

tress

, Pa

A, 1 mm

C, 1 mm

D, 1mm

1 mm die only

bws aV τ=

Slip flow modelling

Compuplast Flow2000™

15

Slip flow characterisation

• Intercomparison of determination of slip velocity measurement

• Assessment of uncertainties in slip velocity determination

• Good Practice Guide• Input to development of ISO 11443 on capillary

and slit die extrusion rheometry• Input to flow simulation software development

16

Slip flow measurements by capillary extrusion rheometry (NPL GPG90)

http://www.npl.co.uk/materials/polyproc/research_projects/mpp74_overview.html

17

Thermal and rheological characterisation of filled materials

Investigation of thermal and rheological techniques for assessing mix quality

Thermal Differential Scanning Calorimetry (DSC) measurement of crystallisation behaviour and Tg

RheologicalDynamic rheological measurements

Case studies

18


DSC good repeatability/good

reproducibility

DMA good repeatability/poor

reproducibility

NPL Good Practice Guide 62

DSC temperature calibration (melting point of indium, 95% confidence) +/- 0.25 °C

Tg by DSC Repeatability

(95% confidence)

Reproducibility (95%

confidence) Unreinforced

polyester 3.9 °C 6.1 °C

Epoxy adhesive 2.9 °C 12.9 °C

19


Tg

20

Thermal and rheological characterisation of filled materials Crystallisation

Melting

Cooling

Heating

21


Crystallisation

Melting

Cooling

Heating

22


Crystallisation

Melting

Cooling

Heating

23

H4: Flow properties of filled materials

Industrial input: e.g. materials,

industrial trials, equipment

Measurements for dispersion Case studies:

Compounding for nano-fillers,

micro-mouldingRheometry, Tg, other

Your input to steer the project

to maximise the benefits to youSimple QC / inline techniques

24

U4: Dynamic properties of solid/liquid materials systems at the nano and micro-scale(2005-08)

Industry need to measure and understand the behaviour of materials on the nano and micro-scale, particularly where scale effects are significant, if they are to develop successfully micro- and nano-technologies (e.g HTT).

Process monitoring is key to improving quality and profitability but is often expensive to implement. Through the development of small-scale instrumentation, process monitoring will become more attractive and cost effective.

To address such issues this project aims to develop new innovative capability to measure the dynamic properties of materials

• Development of a macro scale resonating piezoelectric cantilever device for fluid rheology, and validated using a range of reference fluids

• Design and development of prototype nano-mechanical tester (NTM3D) based in an SEM for measurement of solids

25

Micro-rheology

l = 4.5mm, h=0.16mm, w=0.4mm

0

50

100

150

200

250

300

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8Viscosity, Pa.s

Q fa

ctor

25 °C

Q factor = resonant frequency/bandwidthbandwith = width where the level falls below 1/sq root 2

tuning fork as used in digital watch

26

Piezoelectric device

Piezoelectric PZT cantileverSupporting structure

tiliqinliq eFEI

tbb

tSA ωζλ

ζζρρ −=+

∂∂

++∂∂

+ 0141

21

2

)()(

Vibrating cantilever immersed in fluid behaviour

3311111 EdS E +Χ=χPiezoelectric behaviour

3331313 EdD Xε+Χ=

27

Use of piezoelectric devices for small-scale rheological measurement

Piezoelectric – electrical driving force, varying frequencyMeasure – electrical conductance G and capacitance C of device

C0R

CLC0R

CLC0R

CL 22 )1(

CLR

RG

ωω −+

=Equivalent circuit

Applications:e.g. in-situ measurement

Resonant frequency dependent on surrounding fluid: measures of viscosity and density

28


Resonant frequency dependent on surrounding fluid: measures of viscosity and density

0

1x10-5

2x10-5

3x10-5

4x10-5

G (S

)

0

2x10-10

4x10-10

6x10-10

8x10-10

1x10-9

1x10-9

60005000

C (F

)

Frequency (Hz)

Applications:e.g. in-situ measurement

electrical conductance G and capacitance C

29


0

1x10-5

2x10-5

3x10-5

4x10-5

G (S

)

0

2x10-10

4x10-10

6x10-10

8x10-10

1x10-9

1x10-9

60005000

C (F

)

Frequency (Hz)

Frequency

Con

duct

ance

30


0

0.000005

0.00001

0.000015

0.00002

0.000025

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

Frequency

Con

duct

ance

G raw data

G fitted curve

Parameter Value Error----------------------------------------R 43426.23886 75.43748L 30.59421 0.06205C 2.57E-11 5.22E-14B 4.54E-07 6.53E-09

`

31

PZT measurements

1st resonant mode

2nd resonant mode

3rd resonant mode

32

PZT measurements

1

10

100

1000

0.1 1 10 100 1000(Viscosity, mPa.s)1/2

R/(L

wo1/

2 )

Resonant peak 1

Resonant peak 2

Resonant peak 3

Resonant peak 4

Resonant peak 5

33

PZT measurements

1

10

100

1000

0.1 1 10 100 1000(Viscosity, mPa.s)1/2

R/(L

wo1/

2 )

Resonant peak 1

Resonant peak 2

Resonant peak 3

34

PZT measurements

y = 33675x-0.0161

y = 505494x-0.0038

y = 905781x-0.0034

y = 1E+06x-0.0016

y = 196980x-0.007

1.E+04

1.E+05

1.E+06

1.E+07

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Viscosity, mPa.s

Res

onan

t fre

quen

cy w

o

Resonant peak 1

Resonant peak 2

Resonant peak 3

Resonant peak 4

Resonant peak 5

Resonant peak 1

Repeatability of ωο: 0.01% undisturbed, 0.6% disturbedEquivalent repeatability of viscosity: 0.6% undisturbed, 27% disturbed

35

PZT measurements

y = 33675x-0.0161

y = 505494x-0.0038

y = 905781x-0.0034

y = 1E+06x-0.0016

y = 196980x-0.007

1.E+04

1.E+05

1.E+06

1.E+07

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Viscosity, mPa.s

Res

onan

t fre

quen

cy w

o

Resonant peak 1

Resonant peak 2

Resonant peak 3

Resonant peak 4

Resonant peak 5

Resonant peak 1

Repeatability of ωο: 0.01% undisturbed, 0.6% disturbedEquivalent repeatability of viscosity: 0.6% undisturbed, 27% disturbed

35600

35700

35800

35900

36000

36100

36200

36300

36400

0.018199995 0.0182

International standards activities on rheological measurement of plastics

http://www.npl.co.uk/materials/polyproc/iso.html

Next ISO TC61 meeting to be held in September 2007

37

Developments in rheology standards

ISO TC 61 (Plastics) SC5 (Thermophysical properties) WG9 (Rheology) -Chairman

Represent UK interests in the revision of ISO rheological standards and the drafting of new standards

– Melt flow rate (MFR/MVR) – ISO 1133 – Capillary extrusion rheometry – ISO 11443– Extensional viscosity (tensile drawing method) – ISO 20965– Drawing characteristics of molten thermoplastics (fibre-spinning method) – ISO 16790– Oscillatory rheometry - ISO 6721-10– Pressure-volume-temperature (pvT) – ISO 17744

– Acquisition and presentation of comparable multipoint data: Thermal and processing properties – ISO 11403-2

– ISO guide for the acquisition and presentation of design data for plastics - ISO 17282

38

ISO 1133 Melt mass-flow rate (MFR) and melt volume-flow rate (MVR) Recently revised (published 2005):

Incorporation of additional die (half normal length and half normal diameter) to enable higher MFR/MVR value materials (MFR>75) to be measured

Removal of dead-weight specificationRevised temperature tolerances

Future revisions:

moisture sensitive/high MFR/MVR materials

preparation of a consolidated charge

inclusion of novel NPL tests features

39

Melt flow rate testing for moisture sensitive materials

Application:PET, PBT, PEN, Nylons, other polyesters

Avoidance of intrinsic viscosity measurement ISO 1628-5 Determination of the viscosity of polymers in dilute solution using capillary viscometers – Part 5: thermoplastic polyester (TP) homopolymers and copolymers

Benefits in time, cost, not requiring toxic / hazardous solvents

Problems:• hydrolysis

• low viscosity (high MVR)

• air entrapment problem and consequences (especially with recyclate, e.g. flake)

• greater sensitivity to thermal history

40

Melt flow rate testing for moisture sensitive materials

Intercomparison:

To provide precision data and statement to ISO 1133 for both current and moisture sensitive parts

Led by NPL

Participants welcomed

41

Melt flow rate testing: potential developments

Sample preparation:

Related problem for recycled polymer, flakes, film, shredded product samples, e.g. PET bottles (low bulk density).

Pre-forming of charge using cylinder (9.55 mm diameter) under vacuum.

Temperature 241 °C +/- 1 °C

Load 1.5 kN +/- 0.5 kN

Charge 6 g to 10 g sample

Incorporation of short die specification:

For determination of extensional flow properties

Particularly relevant to blow moulding, film blowing, vacuum forming

42

Potential future developments in standards for plastics

• On-line viscosity measurement

• Rotational rheometry- steady shear, creep/stress relaxation, calibration of,

• Determination of no-flow temperature

• Other? – your say

43

Summary

• Slip intercomparison – slip velocities within approx. +/- 20%

• Crystallisation behaviour shows most promise of thermal techniques for differentiating filled materials

• Industrial input for case studies being developed• Assessment of piezoelectric device for rheological

measurement has identified various strengths and weaknesses of technique

• ISO standardisation of MVR/MFR testing of moisture sensitive materials progressing

44

Next twelve months

• Technical/industrial case studies on mix quality

• Further explore use of thermal and rheological techniques for

evaluating dispersion quality (case studies)

• Further assessment of small-scale rheological devices (reduction in

size issues)

• Progress standardisation of moisture sensitive MVR/MFR method

• Intercomparison on MFR/MVR in support of standards activity

45

http://www.npl.co.uk/materials/polyproc/

Acknowledgements:DTI

Crispin Allen, Angela Dawson, Don Fleming, Adrian Kelly, Barry Howarth,

http://www.npl.co.uk/materials/polyproc/

flow properties of filled materials and standards...

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