new elastomer applications - tut · nbr. examples from ongoing research ... 150 nm incorporated in...

Amit Das1,2, Minna Poikelispää1, Alexandra Shakun1, Jyrki Vuorinen1

1Department of Materials Science, Technical University of Tampere, Finland2Leibniz-Institut für Polymerforschung Dresden e.V., Germany

New Elastomer Applications

Exploitation of rubber formulations

• A crosslinked polymer (high molecular weight) Rubber

StretchedRelaxed

• Peroxide• Organic peroxide

• Co-agent• Antioxidant• Antiozonant

• Processing aid• Mastication agent

• Fillers• Dispersing agent

• Sulphur• Organic accelerator

• Sulphur• --• --• --• --• --

Mainly two different ways ofcrosslinking

2

Examples from ongoing research

Artificial Muscles by DielectricElastomers

Sensor Materials fromElectrically Conducting Rubbers

Self-healing Rubber Materials

4

Artificial Muscles by DielectricElastomers



5

Voltage off Voltage on

Weight lifting by Maxwell stress, source: JAppl Phy 112, 041101 (2012)

Dielectric elastomer actuator (DEA) can have more promising future in the application of artificialmuscles due to its physical nature like human muscle and various adjustable properties whichcan be tailored according to the demand.

Dielectric elastomer for artificial muscles

6

Dielectric materials:

• High polarity

• Low modulus, Y

• High relative dielectric permittivity, ε’

• Low dielectric losses, ε’’

Electrodes:

• Compliant

• Durable

• High electric conductivity

• Easy fabrication• Design freedom• Cost efficiency• Reasonable life-time• High performance (low

energy loss)

State of the art

Most of the actuator materials based oncommercial silicone rubber or ACM tape from 3M 7

DEAs usually require high operating electricfields E (up to 100 kV/mm)

Modification of general purpose rubbers

8

Actuation behaviour

Commercial ACM tape

• Well-studied

• Used in large number of articles

Reference samples

• Compounded and fabricated atTUT

75% prestrain

0

1

2

3

4

5

6

1 3 5 7 9St

ress

,kPa

Electric field, kV/mm

3M tape NBR3330

Reference sample ACM NBR

Dielectric permittivity 6.6 18.3

Modulus 0.97 MPa 1.66 MPa

ε’/Y ratio 6.8 11.0

3M adhesive tape VHB4910

Dielectric permittivity 6.4

Modulus 0.88 MPa

ε’/Y ratio 7.3

00.20.40.60.8

11.21.41.61.8

1 2 3 4 5 6 7 8

Stre

ss,k

Pa


3M ACM 75% prestrain

9

Actuation performance of general purpose rubbers

02468

10121416

1 3 5 7

Stre

ss,k

Pa


neatLNBR5F5DOA5

0

0.4

0.8

0 5 10Actu

atio

nst

ress

,kPa


ACM (pure)

ACM + Dielectric Filler

4

8

12

16

1.00E-01 1.00E+02 1.00E+05

Rela

tive

perm

ittiv

ity,-

Frequency, Hz

0

0.4

0.8

1.2

1.6

2

0 5 10

Actu

atio

nst

ress

,kPa


NBR 3330

NBR 3945

XNBR

ACM(dual)

CO

NR

Dielectric transformeroil, Fomblin (F)Liquid nitrile rubber(LNBR)Dioctyl adipate (DOA)

BaTi

O3

Tailor-madeproperties General purpose rubber can be formulated according to the desire way can be utilised

as dielectric actuator materials. The use of dielectric filler the permittivity of the acrylicrubber increases and enhances the actuation performance.

10

NBR


Artificial Muscle by DielectricElastomers



11

Elastomeric Sensor Materials

R [ ]WR [ ]W

R [ ]WR [ ]W

e

1 10 100

200

400

600

800

1000

Rel

.res

ista

nce

(%)

Strain e [%]

Rubber-based Piezoresistive Strain Sensors or Conductors

Schematic illustration of piezorestistive strain sensing in rubber filledwith electrical conductive carbon nanotubes

Dependence of the electrical resistance on strainof a piezorestistive rubber material

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conductors

sensors

Elastomeric sensors

13

0 10 20 30 40 50 600

200

400

600

800

1000

Res

ista

nce

kOhm

Strain (%)

3 CNT 3.5 CNT 4 CNT 5 CNT

Strain, pressure sensors and body movement monitoring based on conducting elastomers

10 10010-2

10-1

100

101

102

103

104

DR

/R0

% Strain

MWCNT 2.75 phr MWCNT 3 phr MWCNT 4 phr

0 100 200 300 400 50010-2

10-1

100

101

102

Time (sec.)

Rel

.Res

ista

nce

0

50

100

150

200

250

300

Strain

(%)

13

Specialdispersiontechnique

Dynamic Piezoresistive Sensor Materials

• Stress, strain and relative resistance responses of in 5 sec window

• In accordance to the strain, there is a proportionate response for stress and resistance

DMA – equipped with electricalresistivity measurement

top: dynamic mechanical measurement (force / strain)bottom: dynamic resistivity / conductivity measurement

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0 1 2 3 4 5

-40

-20

0

20

40 Strain [%] Stress [MPa] Rel. resistance [%]

Time [s]

-1

0

1

-100

0

100

Response of the electrical resistance ondynamic mechanical stress / strain

Dynamic Piezoresistive Sensor Materials

s id ew al l

p iezo -res is tivesenso r

s id ew al l

p iezo -res is tivesenso r

Possible application:• Piezoresistive sensors in tires for

information on running conditions, oscillationfrequencies of the tire, acceleration signals,temperature, deflation, rolling resistance,roughness of the road surface, tire wear, orfatigue of the tire

• structural health monitoring of elastomermaterials, as sealing gaskets, bearings …

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Elastic Conductors: Hybrid fillers:

Special Carbon BlackDBP number : 350 - 410 ml/100gSurface Area: 1002 m2/gPrimary particle size: 35nm

Special silica(Sidistar)Surface Area: 20 m2/gPrimary particle size: 150 nm

Incorporated in S-SBR together

• Very high structure carbon black with very large surface area• Non reinforcing microsize silica particles (Sidistar) with very low surface

area

Special Rubber Composites

Synergisticeffect!!!

16

Development of highly electrical conducting elastomers

40 50 60 70 80 90 10010-3

10-2

10-1

elec

tric

alvo

l.co

nduc

tivity

(S.c

m-1

)

Amount of Sidistar

with Sidistar

without Sidistar (20 phr CB)

Eshwaran et al. Manuscript under preparation 17

0 100 200 3000

10

20

30

40

Time (s)

Res

ista

nce

(MO

hm)

Stra

in(%

)

0

50

100

150

200

0 100 200 300 400 5000

200

400

600

800

1000

Time (s)

Res

ista

nce

(kO

hm)

Stra

in(%

)

0

4

8

12

16

20


Artificial Muscle by DielectricElastomers



18

Example of Self-healing and literature!

19

• Viscous liquids

• Raw rubbers

• Thermoplastics

Water has also a self-healing character!

Intrinsic nature of aviscous polymer!

Macromol. Chem. Phys. 2012, 213, 234−242

Self-healing materials are smart materials that can intrinsically repair damageleading to longer lifetimes, reduce inefficiency caused by degradation.

An un-crosslinkedrubber has always

a self-healing tendency

This rubber cap is alsocapable to self-

healing!

Butyl and bromobutyl rubber application

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• Very low gas permeability• Chemicaly inert• High tensile strength• Heat and weathering resistant• High damping

-150 -100 -50 0 50 100

0.0

0.5

1.0

1.5

tand

Temperature °C

Natural Rubber

Butyl Rubber

Typical dynamic mechanical pattern of Butyl Rubber

bromination

Bromine modifiedPoly-isobutylene-

isoprene co-polymer(BIIR)

Modification of the BIIR

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ΔT

0 5 10 15 20 25 300

5

10

15

20

25

30

35

BIIR and butyl imidazole at 85°C

Torq

ue(N

m)

Time (min)

pure BIIR at 85°C

0 5 10 15 20 25 300

5

10

15

20

25

Torq

ue(N

m)

Time (min)

pure BIIR at 40°C

BIIR and Butyl imidazole at 40°C

Modification of the bromobutyl rubber by imidazole (polyisobutylene-isoprene copolymer)

Torque time curves for the mixing of BIIR and butyl imidazole obtainedfrom an internal mixer (Thermo Hakke Rheocord Polylab), capacity of 75

ml and the rotor speed was 60 rpm

Network formation by ionicassociation

Self-healing nature of modified BIIR

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Modified rubber strip was cut into two pieces and allowed to mend for 24 hrs and finally tested!

Direct Self-healing Test

Healing was carried out at room temperature after keeping the damaged samples for 1h to 192 h(black); some samples were kept at 100 °C for the first 10 min of the total healing time (red) 23

Test of self-healing

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Acknowledgement

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Phd studentsEshwaranSankarDebdiptaAladdin….

new elastomer applications - tut · nbr. examples from ongoing research ... 150 nm incorporated in...

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