Measurement methods related to the processing and...

4 March 2004 1Polymer Processing and Performance IAG

Measurement methods related to the processing and performance of plastics

Dr Martin Rides

MPP7.4: Processing behaviour of multi-phase materials

Industrial Advisory Group Meeting


Summary

Project rationaleProject summaryLiterature reviewPreliminary results of rheological measurements of highly filled materialsUpdate on rheological standards in ISOThe future


Rationale / backgroundThe 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 flow behaviour of multi-phase materials is complex and will be affected by factors including the:

solids content (phase volume)geometry of the particlessurface finish of the particlessize distribution and shape of the particlessurface energy – whether or not the particles flocculate

• adsorbed species (e.g. polymers, surfactants)• hydrophilic/hydrophobic nature of particles relative to continuous phase


Flow of multi-phase materials is a multi-sectoral issue

The reliable measurement of the flow behaviour of multi-phase is relevant to many industrial sectors and is important to, for example:

materials design and selectionprocess modelling (design, optimisation)

Sectors potentially addressed in this project:

PlasticsElectronics interconnections (soldering/conducting adhesives)Metals processing (thixo-casting)Ceramics processingPersonal hygiene (soaps)


BenefitsMain outputs

Better methods for characterisation of the flow behaviour of highly filled materialsImproved understanding of the role of apparent slip in processingImproved materials models

Resulting benefitsImproved materials selectionImproved materials developmentImproved materials quality controlImproved process modellingImproved process designImproved product qualityReduced scrap ratesReduced time to market


Project summary

Task 1: Review of measurement and modelling technology for multi-phase materials, and initial experimental and modelling assessment of slip flow

Task 2: Measurement for slip and shear thinning flow behaviour of multi-phase materials

Task 3: Appraisal of effect of slip phenomenon

Task 4: Standards and dissemination activities


Task 1Review of measurement and materials modelling technology for flow of multi-phase materials, to identify good practice and establish potential for transfer of such technology between sectors

• Sectors potentially covered: plastics, liquid metals, electronic interconnections and ceramics


Some fillers used in polymersAlumina Quartz Titanium

dioxide

Calcium carbonate

Talc Carbon black

Clays Fly ash Glass fibre

Ferromagnets Jute fibre Powdered metals

Gypsum Magnesium hydroxide

Wood flour

Mica Silicas etc


Effect of filler on flow of polymeric systems

Shear viscosityNo filler Cross-type behaviour

(shear thinning with plateau at low shear rates)

(Near) spherical,non-interacting

Increase in viscosity

(Near) spherical, interacting

IncreaseApparent yield stress possible

Long fibres Greater shear thinning



Entrance pressure drop

No filler Power-law


Increase


Increase

Long fibres Very significant increase



Linear viscoelasticityG’ & G’’

No filler Cox-Merz holds (relates complex to steady shear viscosity)


Increases. Increase in G’ ≤ G’’


Decrease

Long fibres Large increase

( ) ( )ωηγη *=&



Non-linear viscoelasticityN1, N2

No filler N1 = + veN2 ≈ - N1 /10


N1 increases slowly, N2increases. Elasticity increases. Elasticity decreases



Elasticity = N1 / σ



Extrudate swell:

effect of filler predominantly to reduce extrudate swell and

reduce recoverable shear strain


Effect of filler on shear viscosity of dilute Newtonian systems - Einstein

φηη 521 .

o

+=

Einstein equationη = viscosity of suspension of filler particlesηo = viscosity of Newtonian liquid= phase volume of filler particleφ


Effect of filler on shear viscosity of Newtonian systems

2

1−

⎥⎦

⎤⎢⎣

⎡−=

mo φφ

ηη

Marron – Pierce – Kitanoη = viscosity of suspension of filler particlesηo = viscosity of Newtonian liquid= phase volume of filler particles= maximum phase volume (at which η→ ∞)

φmφ

m

o

φφ

ηη

−=1 mo yieldsvsofPlot φφηη


Effect of filler on shear viscosity of non-Newtonian systems

n

mo

2

1−

⎥⎦

⎤⎢⎣

⎡−=φφ

ηη

Marron – Pierce – Kitano-Quemadaη = viscosity of suspension of filler particlesηo = viscosity of non-Newtonian liquid= phase volume of filler particles= maximum phase volume (at which η→ ∞)

n = power-law exponent

φmφ

m

no

φφ

ηη

−=⎥⎦

⎤⎢⎣

⎡1

21

MPKQ equation


Presentation of effect of filler on shear viscosity of polymeric systems

100

1000

10000

100000

0.01 0.1 1 10 100 1000

Shear rate, 1/s

She

ar v

isco

sity

, Pa.

s

Increasing filler level

Curve shift


Presentation of effect of filler on shear viscosity of polymeric systems

100

1000

10000

100000

100 1000 10000 100000Shear stress, Pa

She

ar v

isco

sity

, Pa.

s

Increasing filler level

Curveshift


Effect of filler on shear viscosity of polymeric systems using the MPKQ equation

Yilmazer (glass beads in ABS)

Shear stress, Pa

Visc

osity

, Pa.

s


Effect of filler on shear viscosity of polymeric systems

Extensional viscosity ηE

No filler ≥ 3 η complex


Depends on elasticity. Increases but reduces/eliminates extensional strain hardening(Near) spherical, interacting



Particle size issues in rheometry of filled systems

Filler content (% vol)

Particle to gap ratio

25% Filler particle size < 0.1 gap size

50% Filler particle size < 0.01 gap size

Rheometry can be carried out with critical gap size < particle sizee.g. capillary die diameter < length of fibre.


Flow effects in flow of polymeric systems

Particle interactionFlocculation/de-flocculation

Particle depletion e.g. at the wall

Slip behaviourYield behaviour


Project summary – task 2Develop method(s) for the measurement of the slip and shear thinning flow behaviour characteristics of multi-phase materials

• Design and manufacture of rheometry test equipment, including flow visualisation cell

• Evaluation of methods for characterising multi-phase materials

• by end March 2005


Viscosity = f(flow rate, pressure, geometry, temperature)

Schematic of a capillary extrusion rheometer

Piston head

Piston

Pressuretransducer

Capillary die

Heater

Barrel wall

Sample


Shear flow pressure drop

Stagnant / vortexregion

Piston head

Piston

Pressuretransducer

Capillary die

Heater

Barrel wall

Sample


Shear flow pressure drop

Stagnant / vortexregion


Slip flow


Extrusion pressure traces for short and long dies at various increasing piston speeds for an EVA at 160 °C

ROS176c HHV000 EVA 160 °C

0

5

10

15

20

25

30

35

0 20 40 60 80 100Time

Ext

rusi

on p

ress

ure

- lo

ng d

ie, M

Pa

0

1

2

3

4

5

6

7

8

9

10

Ext

rusi

on p

ress

ure

- sh

ort

die,

MP

a

Long die (Axis Y1)Short die (Axis Y2)


Extrusion pressures for short and long dies as a function of extrusion speed indicating “slip”


0

5

10

15

20

25

30

35

0 200 400 600 800 1000Apparent shear rate, 1/s

Ext

rusi

on p

ress

ure,

MP

a

Pl

Ps



100

1000

10000

100 1000Apparent shear rate, 1/s

App

aren

t she

ar v

isco

sity

, Pa.

s

Apparent shear viscosity of a PVC at 165 °C


100000

1000000

10 100 1000 10000Apparent shear rate, 1/s

She

ar s

tress

, Pa

ROS153 HHV000ROS176 HHV000ROS176b HHV000ROS176c HHV000ROS176d HHV000ROS175 HHV000 - 2mm diameter

Shear stress plot for an EVA (HHV000) at 160 °C indicating “slip”


100000

1000000


She

ar s

tress

, Pa

ROS159 HHW000ROS169 HHW000 2mmROS171b HHW000ROS171a HHW000ROS171c HHW000

HHW000, EVA, 160 °C

Shear stress plot for an EVA (HHW000) at 160 °C indicating “slip”


Shear stress plot for two EVA materials indicating “slip” (HHV000 and HHW000) at 160 °C

100000

1000000

10 100 1000 10000 100000

Shear rate, s-1

She

ar s

tress

, Pa

ROS159 HHW000ROS169 HHW000 2mmROS171b HHW000ROS171a HHW000ROS171c HHW000ROS153 HHV000ROS176 HHV000ROS176b HHV000ROS176c HHV000ROS176d HHV000ROS175 HHV000 - 2mm diameter

EVA, 160 °C


y = 81247x0.2974

R2 = 0.9987

y = 54265x0.3068

R2 = 1

y = 60023x0.2687

R2 = 0.9623

100000

1000000


She

ar s

tress

, Pa

Slip (1 mm diameter die)

Slip (2 mm diameter die)Assumed no slip

condition

Fitting shear stress data for an EVA material to model “slip” (HHV000 at 160 °C)


y = 8.159E-01x + 1.714E+02

y = 4.907E-01x + 1.818E+02

y = 2.725E-01x + 1.627E+02

y = 1.354E-01x + 1.279E+02

0

400

800

1200

1600

2000

500 1000 1500 2000 25001/(die radius, m)

App

aren

t she

ar ra

te, 1

/s

300000350000400000450000

Shear stress, Pa

Determination of slip velocity from the gradient of constant shear stress data for an EVA material (HHV000 at 160 °C)


y = 1.854E-26x4.430E+00

-0.05

0

0.05

0.1

0.15

0.2

0.25

0 100000 200000 300000 400000 500000Shear stress (Pa)

Slip

vel

ocity

, m/s

Slip velocity determined from extrusion data for an EVA material (HHV000 at 160 °C)


y = 1.854E-26x4.430E+00

-0.05

0

0.05

0.1

0.15

0.2

0.25

0 100000 200000 300000 400000 500000Shear stress (Pa)

Slip

vel

ocity

, m/s

2 mm die, 69%1 mm die, 79%

Slip velocities determined from extrusion data for an EVA material (HHV000 at 160 °C)


Complex slip flow


100

1000

10000

1 10 100 1000Apparent wall shear rate, 1/s

App

aren

t she

ar v

isco

sity

, Pa.

s .

643

Die diameter, mm

Effect of capillary die diameter on flow of fibre filled material


1000

10000

100000

1000000

1 10 100 1000Apparent wall shear rate, 1/s

Wal

l she

ar s

tress

, Pa

643

Die diameter, mm

Effect of capillary die diameter on flow of fibre filled material


0

20

40

60

80

100

120

0 100 200 300 400 500 600 7001/ (radius, m)

App

aren

t wal

l she

ar ra

te, 1

/s . 30

4050

Wall shear stress, kPa

Determination of slip flow velocity for fibre filled material: negative gradient implies “negative slip”


Flow visualisation

High flow rate, shear rate = 5 s-1

Low flow rate, shear rate = 0.1 s-1


Complex flow


0

10

20

30

40

50

60

70

0 20 40 60 80 100 120Time

Ext

rusi

on p

ress

ure,

MP

a

Long dieShort die

ROS152

Extrusion pressure traces for short and long dies at various increasing piston speeds for a ceramic paste

4 March 2004 4Polymer Processing and

Extrusion pressure traces for short and long dies with cone entries at various increasing piston speeds for a ceramic paste

0

5

10

15

20

25

30

35

0 50 100 150 200 250Time

Ext

rusi

on p

ress

ure,

MP

a

Long die with cone entryShort die with cone entry

ROS151


10

100

1000

100 1000 10000Apparent shear rate, 1/s

App

aren

t she

ar v

isco

sity

, Pa.

s

ROS152

ROS151 -cone entry

Apparent shear viscosity of a ceramic paste: effect of cone or flat entry geometry


0.1

1

10

100

0 100 200 300 400 500Time

Ext

rusi

on p

ress

ure,

MP

aShort dieLong die

ROS149b

Extrusion pressure traces for short and long dies at various increasing piston speeds for a ceramic paste


Use of ultrasonics to improve flow performance

Ultrasonics has been demonstrated to have an effect on polymer melt flow

Can it be used to aid difficult rheological measurement?


Project summary – task 3Numerical simulation to validate data generated by improved techniques

• Simulation of experimental configurations

• Simulation of industrial processing configurations

• by end Sept 2005


Project summary – task 4International standards activities on rheologicalmeasurement of plastics (to continue dissemination of the work of previous projects’ outputs as well as this project’s outputs)

Dissemination activities / main outputs

• Good Practice Guide on new methodologies• Workshop• Reports, press releases, Newsletter articles scientific paper,

conferences• IAGs


Developments in rheology standardsRepresent UK interests in the revision of ISO rheological standards and the drafting of new standards

MFR/MVR – ISO 1133/DIS: under revision

Capillary extrusion rheometry – ISO/DIS 11443: under revision

Extensional viscosity (tensile drawing method) – ISO/CD 20965: new development

Drawing characteristics of molten thermoplastics (fibre-spinning method) – ISO/CD 16790: new development

Oscillatory rheometry - ISO 6721-10: published


Developments in the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) standard

ISO 1133 MFR/MVR under revision: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

Under consideration: moisture sensitive/high MFR materials, and inclusion of novel NPL tests features,

Status: Standard now progressing to FDIS


Melt flow rate of hot melt adhesives: repeatability when using the short die

0

200

400

600

800

1000

1200

1400

1600

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Scan

Mel

t vol

ume

flow

rate

, cc/

10 m

ins

RR313 MVRAQHN003 shortdie 90 °C

RR311 MVRAQHN003 shortdie 90 °C

RR309 MVRAQFW short die150 °C

RR308 MVRAQFW short die150 °C


Melt flow rate of hot melt adhesives: effect of die length

y = 3.4847x + 1143.7R2 = 0.0102

y = -0.0188x + 46.863R2 = 0.0021

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20 25Scan

Mel

t vol

ume

flow

rate

, cc/

10 m

ins

RR312 MVR AQHN003 long die 90 °C

RR311 MVR AQHN003 short die 90 °C


High melt flow rate testingFor MFR or MVR > 75 the revised ISO 1133 will permit the use of die 4.000 mm +/- 0.025 mm in length, 1.05 mm +/- 0.005 mm in bore diameter

“If testing materials with Melt Mass-Flow Rate >75 g/10 min or Melt Volume-Flow Rate >75 cm3/ 10 min, preferably, a half-height half-diameter die 4,000 mm +0,025 mm in length and nominal 1,05 mm + 0,005 mm in bore diameter should be used. No spacer shall be used with this die to increase apparent length to 8,00 mm. “


High melt flow rate testingFor MFR or MVR > 75 the revised ISO 1133 will permit the use of die 4.000 mm +/- 0.025 mm in length, 1.05 mm +/- 0.005 mm in bore diameter

PET proposal:

Proposal for 1.00 mm +/- 0.01 mm diameter die

Drying 160 °C +/- 3 °C

Test temperature 280 °C

PBT proposal:

No specification on die

Drying > 4 hours at 100 °C and under pressure of < 100 mbar and N2 atmosphere. Moisture < 0.02% (m/m) before testing

Test temperature 250 °C


Developments in capillary extrusion rheometry standard for plastics

Restricted capillary extrusion rheometry testing - improved data comparability

Revision of ISO 11443 on capillary extrusion rheometry

- inc. reduction of long die specification from L/D = 20 to L/D = 16 for two-die determination of true shear viscosities

Status: Standard now progressing to FDIS


Developments in standards for extensional flow properties

ISO/DIS 20965: Determination of the transient extensional viscosity of polymer melts

lo

FType A

F

ω

ω

Status: Standard now progressing to

FDISType C

VF

lo


Developments in standards for extensional flow properties

ISO/DIS 16790: Determination of drawing characteristics of thermoplastics in the molten state

Status: Standard now progressing to

DIS2


Developments in standards for plastics

Oscillatory rheometry – ISO 6721-01. Published

On-line viscosity measurement. Potential proposal

PVT Determination of specific volume as a function of temperature and pressure (piston method), ISO/CD 17744: new standard under development

Acquisition and presentation of comparable multipoint data: Thermal and processing properties – ISO/DIS 11403-2. Progressing to FDIS

ISO guide for the acquisition and presentation of design data for plastics -ISO/DIS 17282. Progressing to FDIS

Determination of no-flow temperature. Proposal withdrawn

Any suggestions?


Specification for plastics waste

BPF Recycling Council led project


SummaryInitial measurements and analysis has clearly demonstrated slip flow of filled EVA materials.

However evidence for “negative slip” flow according to simple theory also demonstrated

Difficulties very apparent in making Rabinowitsch correction formaterials that exhibit slip (Rabinowitsch correction, to obtain true shear viscosity data, is already a main source of uncertainty in true shear viscosity data).

Standards activity on a number of rheological methods progressing –proposal for MFR for PET & PBT: your comments/input welcome


Summary and what next ?Further materials required for studies of flow of multi-phase materials – offers/suggestions welcomed

Process simulation – need to identify potential candidates for process simulation, suggestions welcomed

Increase industrial awareness of projectIndustrial visits / telephone calls

Make your interests known!


THE END


Standards for recycled plastics


Extrusion pressure traces for short and long dies at various piston speeds for a PVC at 165 °C

ROS174 - HHU000 (PVC)

0

5

10

15

20

25

0 50 100 150 200 250Time, s

Ext

rusi

on p

ress

ure,

MP

a Short dieLong die


Extrusion pressures for short and long dies as a function of extrusion speed

ROS174 HHU000 PVC 165 °C

1

10

100


Ext

rusi

on p

ress

ure,

MP

a

PlPs


ROS174 - HHU000 PVC 165 °C

100

1000

10000


App

aren

t she

ar v

isco

sity

, Pa.

s



100000

1000000

100 1000 10000Shear rate, 1/s

She

ar s

tress

, Pa

ROS172 HHU000 2mm

ROS174 HHU000 1mm

ROS174b HHU000 1mm



Studio projects

Intention to develop at least one studio project to tackle more industrially focused issues albeit related to core project activities

Need to identify participants with focused measurement/processing issue(s)

Start date – late 2003


Project flow diagram

Task 1, M1 Task 1, M2 Task 2, M3 & M4 Task 2, M4 and M5 Task 3. M6 Task 4, M7, M8 & M9Review of measurement and modelling technology for multiphase materials, and increase project profile

Initial assessment of slip flow

Measurement of flow behaviour of multiphase materials: design, manufacture and commissioning

Measurement of flow behaviour of multiphase materials: Evaluation of rheometry and flow visualisation methods

Appraisal of effect of slip phenomenem Standards activities

Increase industrial buy into project Obtain materials

Identify likely measurement method options

Identity suitable industrial case studies/candidate materials

Obtain design data and processing conditions

Participate in development of draft Standards

Press release, New sletter article, industrial visits/calls

Carry out initial experimental assessment of slip

Assess uncertainties for likely methods Obtain materials samples

Simulation of experimental configurations

ISO/TC61 Plastics meetings

Obtain use of modelling softw are (Flow 2000)

Perform measurements on a range of materials

Simulation of industrial configurations

Publicise standards activities

Simulation of experimental configurations

Design, manufacture and commission developments to rheometry equipment

Analysis of experimental data

Report on simulation activities

Presentation to IAG on slip f low characterisation and modeling

Correlation of rheometry w ith f low visualisation data

Publicise initial IAG meeting/project start-up

Review of measurement and modelling technology

Design, manufacture and commission flow visualisation equipment

Develop interpretation of data in terms of appropriate model(s) Rheology w orkshopMeasurement Good Practice Guide Conference paper IAG meetings

NPL New sletter articles

Task 4, M7, M8 and M9Dissemination activities


Measurement methods related to the processing and performance of plastics

Dr Martin Rides

Update on Standards development

Industrial Advisory Group Meeting


Project milestones summary

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

M1 Review of measurement and modelling technology

M2 - Initial assessment of slip flow

M3 Equipment design and manufacture

M4 Equipment commissioning

M5 Method evaluation

M6 Simulation

M7 Standards and dissemination 1



2002 2003 2004 2005


10000

100000

1000000

100 1000 10000Apparent shear rate, Pa.s

She

ar s

tress

, Pa.

s ROS152

ROS151 -cone entry

Plot


0.1

1

10

100

100 1000 10000Apparent shear rate, 1/s

Ext

rusi

on p

ress

ure,

MP

a

Pl - cone entry 151Ps - cone entry 151Pl 152Ps 152

Plot


Developments in rheology standardsRepresent UK interests in the revision of ISO rheological standards and the drafting of new standards

Melt flow rate (MVR/MVR) – ISO/FDIS 1133

Capillary extrusion rheometry – ISO/FDIS 11443

Extensional viscosity (tensile drawing method) – ISO/DIS 20965

Drawing characteristics of molten thermoplastics (fibre-spinning method) – ISO/DIS 16790

pvT (pressure-volume temperature) – ISO/DIS 11774

Oscillatory rheometry - ISO 6721-10: published

On-line viscosity measurement


Development of on-line rheological properties standard for plastics

MPM1.4 In-process measurements during polymer processing – Bradford University

At-Process measurements re performance of processing/ materialsLinks between in-process measurements and product parameters

Proposal for on-line viscosity/MFR&MVR standard:accepted, in principal, by ISO TC61/SC5/WG9 Melt Rheology committee


Major project outputs

• At least 1 new or improved measurement methods• 1 Measurement Good Practice Guide• At least 1 workshop• At least 1 scientific paper• At least 2 articles aimed at industrialists


A team effort

Barry Haworth,Loughborough University

Dr Don Fleming, Fleming Polymer Testing and Consultancy

Chris Hunt et al, Electronics Interconnections, NPLPeter Quested et al, Liquid Metals, NPL


Main beneficiaries

· Suppliers of materials - through improved methods for materials characterisation resulting in benefits in materials development and quality control

· Designers, through improved materials characterisation and process modelling

· Processors, through improved methods for materials selection andprocess modelling leading to larger processing windows, and better quality control leading to less down-time and lower scrap rates

· Research and technology centres and process simulation software providers, through improved measurement technology providing improved data and potentially improved flow models

· Scientific instrument manufacturers, through exploitation of more appropriate test methods and the existence of well-founded standards

Measurement methods related to the processing and...

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