Preparation, Structure and Properties Preparation, Structure and Properties of the Nano Reinforced; Thermal of the Nano Reinforced; Thermal Conductive Rubber Composites Conductive Rubber Composites

Lu, Lu, YonglaiYonglai; Zhang, ; Zhang, LiqunLiqun; ; FengFeng, , YaolingYaoling; Wang, ; Wang, ZhenhuaZhenhua; ; Ding, Ding, JingboJingbo

ContentsContents1. Introduction and Background2. Nano-ZnO filled systems3. Nano-Al2O3 filled systems4. Conclusions5. Acknowledgement

1. Introduction and Background1. Introduction and BackgroundAs well known to us，due to high elastic feature of rubber, many products working in dynamic condition must be made of rubber.

Tyre

Rubber Belts

In order to satisfy the practical applications, rubber reinforcement is very essential and necessary. Among all kinds of methods, compounding nano fillers is the most effective. Some traditional therories in rubber reinforcement have been developed on basis of much previous research work

1. Introduction and Background1. Introduction and Background

1 Strong bond and weak bond theory[1]

2 the model of the limited extensibility of rubber[2]

3 molecular chains slippage model [3]

4 Glass Shell Model [4]

[1] Naunton W J S. The applied science of rubber [M]. Edward Arnold Ltd.: London, 1961: 207-253.[2] Kraus, G. Reinforcement of Elastomers [M]. (Ed) Interscience Publishers: New York, 1965: 125-152.[3] Thor L. Smith, James A. Rinde. Ultimate tensile properties of elastomers. V. Rupture in constrained biaxial tensions [J]. Journal of Polymer Science Part A-2: Polymer Physics, 1969, 7(4): 675-685.[4] Boonstra B B. Mixing of carbon black and polymer: Interaction and reinforcement [J]. Journal of Applied Polymer Science, 1967, 11(3): 389-406.

Theories In Rubber

Reinforcment

Theories In Rubber

Reinforcment

“Nano-reinforcing is the predominant condition for the efficient reinforcement of rubber.” “Nano scale is necessary for efficient reinforcing rubber.” These viewpoints have been verified according to many researchers’ work and practical industry applications. For example: carbon black, with less than 100nm primary particle size, widely used in rubber industry.

1. Introduction and Background1. Introduction and Background

1. Introduction and Background1. Introduction and Background

Rubber-rubber frictionRubber-rubber friction

Filler-filler friction

FillerFiller--rubber frictionrubber friction

Microcosmic causes of heat

build-up

Main factors

Although fillers could endow the rubber product with good performances, but as well increase the heat build-up in dynamic serving conditions.

1. Introduction and Background1. Introduction and Background

Heat build-up

Heat build-up

Poor thermal conductivityPoor thermal conductivity

Heat accumulation leading to the internal high temperature

Heat accumulation leading to the internal high temperature

Deteriorating the utilized propertiesDeteriorating the

utilized properties

Accelerating the aging

Accelerating the aging

Rubber chains will be broken downStructural damage occurs in rubber products

Influencing the service life significantly, even safety problem

Harm of heat build-upHarm of heat build-up

1. Introduction and Background1. Introduction and Background

Schematic view of Bias tyre

Damage in tire shoulder

Much work has been done for improving the dynamic mechanical properties of composites: TWO strategies

Decreasing heat build-up

◆Decreasing the heat build-up，improving the dynamic mechanical properties

Conducting heat build-up

◆Increasing the thermal conductivity of rubber composites, conducting the heat build-up in time, and sovling the heat accumulation

Choosing novel rubber matrix such as SSBR; Increasing the filler-rubber interaction; Improving the filler dispersion, etc.Choosing novel rubber matrix such as SSBR; Increasing the filler-rubber interaction; Improving the filler dispersion, etc.

Filling the thermal conductive fillers, such as short stainlesssteel fiber, etc.Filling the thermal conductive fillers, such as short stainlesssteel fiber, etc.

Main FocusMain

Focus

Advantage：conducting the heat, solving the heat accumulationLimitation：thermal conductive fillers such as steel fiber perform

bad in reinforcing rubber matrix!

Advantage：conducting the heat, solving the heat accumulationLimitation：thermal conductive fillers such as steel fiber perform

bad in reinforcing rubber matrix!

Advantage：simple & effective, widely usedLimitation：Not solving the heat accumulation

from roots !

Advantage：simple & effective, widely usedLimitation：Not solving the heat accumulation

from roots !

1. Introduction and Background1. Introduction and Background

OurAims

• nano particles

Efficient reinforcement

Increasing thermal conductivity

• Thermal condutivefillers

Conducting the heat build-upDecreasing the heat accumulationImproving the dynamic propertiesExtending the service lifeDecreasing heat

build-up

• Inproving the dispersion and filler rubber interaction

Our StrategyOur Strategy

Enhancing the mechanical properties

Novel nano-reinforced thermal conductive rubber compositesNovel nano-reinforced thermal conductive rubber composites

Nano sized thermal conductive fillers, such as nano-ZnO and nano-Al2O3

Exploring the suitable modification method and treatment conditions

Rubber reinforced by nanoRubber reinforced by nano-- ZnOZnO or Alor Al22OO33

2. Nano2. Nano--ZnOZnO filled Systemfilled SystemDispersion morphologyPayne effectMechanism of in-situ modification with silane coupling agent Si69Static mechanical propertiesDynamic mechnical properties

Morphology Morphology observations of observations of nanonano--ZnOZnO particlesparticles

SEM micrographs of nano-ZnO particles

About 50nm

3.1 EPDM-nano ZnO

Dispersion state of nanoDispersion state of nano--ZnOZnO in EPDM in EPDM composites composites

Untreated ZnO filled

TEM images of nano-ZnO filled vulcanizatesLoading: 180phr Volume friction: 18%

TEM images of nano-ZnO filled vulcanizatesLoading: 180phr Volume friction: 18%

Si69 in-situ modified ZnO filled

Payne effectPayne effect

Payne effect of nano-ZnO filled gross rubber: (a) untreated nano-ZnOfilled composites; (b) in-situ modified nano-ZnO filled composites.

Decreased filler network, better dispersion state

Untreated ZnO filled Si69 in-situ modified ZnO filled

Stor

age

mod

ulus

G’/K

Pa

Stor

age

mod

ulus

G’/K

Pa

Strain/% Strain/%

Mechanism of InMechanism of In--situ Modification with Si69situ Modification with Si69——FTIRFTIR

4000 3500 3000 2500 2000 1500 1000

b

a

3448

1090

2926

Wavenumbers/cm-1

2977

Comparison of normalized FT-IR spectra among (a) Si69 pretreated nano-ZnO particles; (b) untreated nano-ZnO particles. (Normalized)

–CH2–& –CH3

–CH2–& –CH3

-OH-OH–Si–O––Si–O–

Mechanism of InMechanism of In--situ Modification with Si69situ Modification with Si69——SchematicSchematic

(a) Reaction between Zinc oxide particles (ZnO) and silicon coupling agent Si69

(b) Reaction between treated Zinc oxide particles (ZnO) and rubber chains

OH

OH

SiO

(CH2)3O-C2H5OH Sa

SiO (CH2)3 Sb

SiC2H5O

C2H5OC2H5O Si OC2H5

OC2H5

OC2H5

S4 (CH2)3(CH2)3

OC2H5

OC2H5C2H5O

ZnO

ZnO

ZnO

SRubber

SiO

(CH2)3O Sa

SiO (CH2)3 Sb

OC2H5

OC2H5C2H5O

SiO

(CH2)3O Sa

SiO (CH2)3 Sb

OC2H5

OC2H5C2H5O

ZnO

ZnO

ZnO

ZnO

Being dispersed and surface modified in the compounds meanwhile, under shear stress and high temperature

During curing, chemical bonds generate between nano particles and rubber chains

Schematic of the reactions during the in-situ modification procedure

0 50 100 150 200 2500

2

4

6

8

10

12

14

16

nano-ZnO nano-ZnO+Si69

Tens

ile s

tren

gth/

MPa

Loading of filler/phr0 50 100 150 200 250

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Stre

ss a

t 100

% e

long

atio

nLoading of filler/phr

nano-ZnO nano-ZnO+Si69

Mechanical properties of nanoMechanical properties of nano--ZnOZnO/EPDM /EPDM compositescomposites

Tensile strength Stress at 100% Elongation

UntreatedUntreated

Si69 in-situ modifiedSi69 in-situ modified

SEM images of tensile section of nano-ZnO filled composites

Loading:180phr Volume fratcion:18%

SEM images of tensile section of nano-ZnO filled composites

Loading:180phr Volume fratcion:18%

0 50 100 150 200 250

0

10

20

30

40

50 nano-ZnO nano-ZnO+Si69

Perm

anen

t set

/%Loading of filler/phr

Mechanical properties of nanoMechanical properties of nano--ZnOZnO/EPDM /EPDM compositescomposites

Elongation at break Tensile permanent set

0 50 100 150 200 250200

300

400

500

600

nano-ZnO nano-ZnO+Si69

Elon

gatio

n at

bre

ak/%

Loading of filler/phr

Nano-ZnO performs well in reinforcing EPDM rubber, and in-situ modification with Si69 can improve the mechanical properties of nano-ZnOfilled composites effectively.

Instrument：FOX50-110 Thermal conductivity tester (Laser Comp, Inc. USA).Conditions：Temp. of cooling and heating calorimeter:20℃ and 40℃

Contact pressure:414KPaSample size：Disc shaped, Φ60mm×6mm

Thermal conductivity of NanoThermal conductivity of Nano--ZnOZnO/EPDM /EPDM CompositesComposites

Dynamic mechanical properties of NanoDynamic mechanical properties of Nano--ZnOZnO/EPDM Composites/EPDM Composites

1 10 1000.0

0.1

0.2

0.3

0.4

0.5

0.6

10 phr 20 phr 40 phr 60 phr 80 phr 110 phr 140 phr 180 phr 210 phr

tanδ

Strain/%

1 10 1000.0

0.1

0.2

0.3

0.4

0.5

0.6

tanδ

Strain/%

10 phr 20 phr 40 phr 60 phr 80 phr 110 phr 140 phr 180 phr 210 phr

Influence of in-situ modification on tanδ of nano-ZnO filled composites as a function of the filler loading

Si69 in-situ modified

In-situ modification with Si69 enhances the filler-rubber interaction effectively, leading to the decreased tanδ

Compression fatigue properties of NanoCompression fatigue properties of Nano--ZnOZnO/EPDM Composites/EPDM Composites

In-situ modification with Si69 improves the compression fatigue properties obviously, espectially at high lodings

0 50 100 150 200 2500

5

10

15

20

25

30

35

40

45

nano-ZnO nano-ZnO+Si69

H /℃

Loading of filler/phr0 50 100 150 200 250

0

2

4

6

8

10

12

14

16

18

20

nano-ZnO nano-ZnO+Si69

D/%

Loading of filler/phr

Influence of in-situ modification on compression fatigue properties of nano-ZnO filled composites

Compression heat build-up Difference D

D represents the difference between ultimate compression deformation rate and initial one

3.3. NanoNano--AlAl22OO33 filled Systemsfilled SystemsDispersion morphologyPayne effectStatic mechanical propertiesDynamic mechnical propertiesExtending to NR system

Morphology Morphology observations of nanoobservations of nano--AlAl22OO33 particlesparticles

SEM micrographs of nano-Al2O3 particles

Morphology of nano Al2O3

Dispersion state of nanoDispersion state of nano--AlAl22OO33 in EPDM in EPDM composites composites

Si69 in-situ modification

TEM images of nano-Al2O3 filled vulcanizatesLoading:149phr ; Volume fraction≈20%

TEM images of nano-Al2O3 filled vulcanizatesLoading:149phr ; Volume fraction≈20%Untreated

Payne effectPayne effect

1 10 1000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0% 2.4% 4.6% 8.9% 11.8% 14.6% 18.1% 20.4%

G'/M

PaStrain/%

1 10 1000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

G'/M

Pa

Strain/%

2.5% 4.8% 9.3% 12.4% 15.3% 18.8% 21.2%

At the same loading, storage modulus G’ of in-situ modified nano-Al2O3 filled composites is lower, which indicates that in-situ modification with Si69 decreases the filler-filler interaction and weakens the filler network effectively.

Influence of in-situ modification on Payne effect of nano-Al2O3 filled EPDM composites

Untreated Si69 in-situ modification

Stress at 100% elongation

0 5 10 15 20 250

2

4

6

8

10

12

14

n-Al2O3 n-Al2O3+Si69

Tens

le s

tren

gth/

MPa

Volume fraction/%0 5 10 15 20 25

0.5

1.0

1.5

2.0

2.5

3.0

3.5 n-Al2O3 n-Al2O3+Si69

Stre

ss a

t 100

% e

long

atio

n/M

PaVolume fraction/%

Untreated

Si69 in-situ modification

Mechanical properties of nanoMechanical properties of nano--AlAl22OO33filled EPDM compositesfilled EPDM composites

Tensile strength

0 5 10 15 20 25250

300

350

400

450

500

550 n-Al2O3 n-Al2O3+Si69

Elon

gatio

n at

bre

ak/%

Volume fraction/%0 5 10 15 20 25

0

5

10

15

20

25

30 n-Al2O3 n-Al2O3+Si69

Volume fraction/%

Perm

anen

t set

/%

Elongation at break Tensile permanent set

nano-Al2O3 also performs well in reinforcing EPDM rubber, and in-situ modification with Si69 can improve the mechanical properties of nano-Al2O3filled composites, as well as nano-ZnO filled systems.

Mechanical properties of nanoMechanical properties of nano--AlAl22OO33filled EPDM compositesfilled EPDM composites

Loading/phr

Volumefraction

/%

Nano-Al2O3/EPDMCompositesλ /[W·mK-1]

In-situ modified nano-Al2O3/EPDM Composites

λ /[W·mK-1]

0 0 0.178 0.17814 2.46 0.197 0.19328 4.81 0.216 0.21342 9.34 0.266 0.25077 12.4 0.304 0.292100 15.3 0.347 0.322128 18.8 0.404 0.374

149 20.4 0.406 0.408

Thermal conductivity of NanoThermal conductivity of Nano--AlAl22OO33/EPDM /EPDM CompositesComposites

Increasing

Increasing

Conditions：Temp. of cooling and heating calorimeter:20℃ and 40℃Contact pressure:414KPa

Sample size：Disc shaped, Φ60mm×6mm

1 10 1000.0

0.1

0.2

0.3

0.4

0% 2.4% 4.6% 8.9% 11.8% 14.6% 18.1% 20.4%ta

nδStrain/%

1 10 1000.0

0.1

0.2

0.3

0.4

2.5% 4.8% 9.3% 12.4% 15.3% 18.8% 21.2%

tanδ

Strain/%

Influence of inInfluence of in--situ modification on situ modification on tantanδδ of nanoof nano--AlAl22OO33filled composites as a function of the filler volume fractionfilled composites as a function of the filler volume fraction

Dynamic mechanical properties of Nano-Al2O3/EPDM Composites

Untreated Si69 in-situ modification

0 5 10 15 20 25

5

10

15

20

25

H /℃

Volume fraction/%

nano-Al2O3

nano-Al2O3+Si69

0 5 10 15 20 25

0

1

2

3 nano-Al2O3

nano-Al2O3+Si69

D/%

Volume fraction/%

Influence of in-situ modification on compression fatigue properties of nano-Al2O3 filled composites with respect to the filler volume fraction

At the same volume fraction, after in-situ modification with Si69 heat build-up decreases and the difference D is improved obviously

Compression fatigue properties of Nano-Al2O3/EPDM Composites

Compression heat build-up Difference D

Extending to NR systemExtending to NR system

(b)

(a)

Mechnical Properties of nano-Al2O3 filled NR composites as function of the filler loading

(b)

(c)

NR filled with 210phr Al2O3 hasThermal conductivity 0.5W/(m.K)Compression heat build-up 16oCDynamic compression permanent set <2%.

Comparison of mechanical (static and dynamic) and thermal conductive properties of composites compounded with in-situ modified nano-ZnO, nano-Al2O3 and traditional reinforcing fillers

3. Comparisons to traditional reinforcing 3. Comparisons to traditional reinforcing fillers filled systemsfillers filled systems

18.3

Loading/phr

Volume fraction/%

Tensile strength/MPa

Elongation at break/%

Permanent set/%

Heat build-up/℃

Difference D/%

λ /[W·m-1·K-1] ℃

Compared to the traditional reinforcing fillers such as carbon black N330 and silica, nano-ZnO and nano-Al2O3 particles assisted by in-situ modification with Si69 increase the thermal conductivity greatly and perform well in reinforcing the EPDM matrix, especially excellent dynamic mechanical properties such as lower compression heat build-up and better fatigue resistance.

4. Conclusions4. Conclusions(1) Nano-ZnO and nano-Al2O3 can enhance the thermal conductivity greatly, and meanwhile perform well in the reinforcing EPDM rubber. However, its dynamic mechanical properties are not good enough. (2) In-situ modification with Si69 can improve the mechanical properties of nano-ZnO and nano-Al2O3 filled composites without influencing the thermal conductivity obviously. Similar results could be obtained in nano-Al2O3 filled NR systems.(3) Compared to the traditional reinforcing fillers such as carbon black N330 and silica, nano-ZnO and nano-Al2O3 particles assisted by in-situ modification with Si69 increase the thermal conductivity greatly and perform well in reinforcing the EPDM matrix, especially excellent dynamic mechanical properties such as lower compression heat build-up and better fatigue resistance.

National Nature Science Foundation of China (NSFC) project (50873007).The National Basic Research Program of China (973 Program), Project Grant 2011CB932603.

5. Acknowledgements

Thanks for your attention!Welcome question.