Improvement of Thermal and Mechanical Properties …Improvement of Thermal and Mechanical Properties...

Improvement of Thermal and Mechanical Properties

of Polyimide Using Metal Oxide Nanoparticles

Ahmad Raza Ashrafϕ,§, Zareen Akhter§, Leonardo C. Simonϕ

ϕ Department of Chemical Engineering, University of Waterloo, Waterloo, Canada§ Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan

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2016 SPE AUTOMOTIVE COMPOSITES CONFERENCE & EXHIBITION (ACCE)September 7-9 2016, Novi, Michigan, USA

Overview

Introduction

• What are polyimides?- History, structure, properties

• Applications- General- Automotive

Synthesis• Polyimide• Polyimide nanocomposites

Results + Conclusion

• Glass transition temperature• Storage modulus• Thermal stability

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• High performance polymers

• Aromatic polyimides consists of1. Heterocyclic imide rings and 2. Aryl groups

linked by simple atoms or groups

What are polyimides?

R

O O

OO

NN

n

R = alkyl or phenyl with or without functional groups

Imide ring

Aryl group

3

History• The first synthesis of polyimide was performed by Bogert and

Renshaw in 1908.

• High-molecular weight aromatic polyimide was synthesized in 1955by Edward and Robinson.

• Poly(4,4'-oxydiphenylene pyromellitimide) widely known as Kapton®was commercialized in early 1960s.

• After the success of Kapton (Dupont), several other PIs have beensynthesized and investigated extensively.

• Commercial examples also include Vespel (Dupont), Upilex (Ube),Meldin (Saint-Gobain).

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Polyimides

Outstanding thermal stability

High glass transition

temperature

Excellent mechanical properties

Chemical and

radiation resistance

Fire and wear

resistance

Low dielectric constant

Low moisture

absorption

Properties

5

6

Why polyimides are so strong???

Charge Transfer Complex

St. Clair, T.L. in Polyimides, Ed. Wilson D., Stenzenberger, H.D., Hergenrother, P.M., Chapman and Hall, New York, 1990, Chapter 2.

• Thin film insulators in electronic packaging.

• Base of flexible white LED strip lights.

• H2O2 sensors.

• Gas separation membranes.

• Lightweight composites of RP46 polyimide and glass fibers are extraordinarilyfire-resistant electrical-insulation materials.

Applications (General)

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• Aerospace structures as outerprotective covering, engine ductsand bushings.

Applications in automotive industry

• The bushings, bearing pads and splines in the 10-stage high-pressurecompressor of the Rolls-Royce BR710 turbofan engine are made fromVespel polyimide. These parts are exposed to temperatures up to 274 °Cyet need no lubrication.

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1. Engineered fluoropolymer jacket2. Braided shield3. Aluminized polyimide shield4. FEP filler5. Color-coded composite dielectric6. Silver-plated copper conductor.

• Aerospace ethernet cables comprise ofaluminized polyimide shield.

• Effective thermal insulation from -240 °C to +204 °C• Inherently fire-resistant• Low cost and fast production• Can be molded into different shapes.

• Polyimide foams: The winner of NASA's 2007 commercial invention ofthe year are effective for sound, heat and cold insulation.

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• Thinner, lighter Vespel® SP-21 thrustwashers replace all-metal needlebearings in a new 7-speed AT for rear-drive vehicles.


• Variable stator vane bushings made fromVespel CP are used in the high pressuresection of the compressor in a aircraftengine. The laminate withstandstemperatures in excess of 675°F.

Applications in automotive industry• DuPont™ Vespel® polyimide bushings offers weight and performance

advantages over metal in exhaust gas recirculation (EGR) valves.

• Due to their stiffness, tensile strength & resistance to friction, wear andhot exhaust gases at temperatures up to 220 °C, these bushings havereplaced metal components in EGR system used in four and sixcylinder stratified-charged petrol engines.

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• Conductive Kapton is used as mirror & seat heaters, enginewarmers of cars, wing, floor and satellite heaters in aerospace.(thermo-llc.com)

• BWD oil pressure light switch has polyimide film diaphragm.

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Applications in Automotive Industry

• The circuits of BWD throttle positionsensors are printed on flexiblepolyimide film for excellent dimensionalstability and for prevention of electricalperformance drift.

• The Dayton audio D250P-8compression driver features polyimidediaphragm for smooth character andrich detailed sound.

Synthesis of polyimideO

O

O

O

O

O

O

BTDA

H2NH2C NH2

MDA

Step 1 2) 25°C1) DMAc

3) 24 hrs stirring

OHN

O O

OOHO

HN

OH

H2C

OO O

OO

H2CNN

n

n

Polyamic acid

Step 2Thermal Imidization

70°C (18hr), 120°C, 150°C, 200°C, 250°C, 280°C (1hr each),

PolyimideBTDA = 3,3',4,4'-benzophenonetetracarboxylic dianhydride MDA = 4,4'-methylenedianiline

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Synthesis of polyimide/nanocomposites

MDA DMAc

MDA/DMAc/NPs

NPs (Nanoparticles)

BTDA

Sonication

Polyamic acid/ Nanocomposite

Stirring Sonication

Polyimide/Nanocomposite

Thermal Imidization25 - 280 °C

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Dang, Zhi‐Min, et al. Advanced Functional Materials 18.10 (2008): 1509-1517

Review: Interaction of nanoparticles with polyamic acid

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Hsu, Shou‐Chian, et al. Macromolecular Chemistry and Physics 206.2 (2005): 291-298.

Interaction between nanoparticles and polyimide

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Research Results

100 150 200 250 300 3500.00.10.20.30.40.50.60.70.8

tan(

d)

Temperature (°C)

BM BM-Al2O3-3% BM-Al2O3-5% BM-Al2O3-7% BM-Al2O3-9%

Polyimide/Al2O3 Nanocomposites

Glass transition temperature (Tg)

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• Pure polyimide (BM)displayed glass transitiontemperature (Tg) at 272 °C.

• Incorporation of Al2O3nanoparticles increased theTg of polyimide matrix.

• Trend was continued withincreasing concentration ofnanoparticles.

• At 9% loading ofnanoparticles Tg wasincreased from 272 °C to337 °C.

BM = polyimide (BTDA + MDA)

50 100 150 200 250 300 3500.00E+000

5.00E+008

1.00E+009

1.50E+009

2.00E+009

2.50E+009

E' (P

a)

Temperature (°C)


Storage Modulus


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• Modulus of pure polyimide (BM)is above 1 GPa up to 250 °C.

• It decreased sharply aroundglass transition temperature(Tg = 272 °C).

• Al2O3 nanoparticles improved themodulus.

• Modulus value at 50 °Cincreased from 1.60 GPa to 2.56Gpa GPa at 9% loading ofnanoparticles.


Polymer Tg (°C) Modulus50

(GPa)

Modulus150

(GPa)

Modulus250

(GPa)

BM 272 1.60 1.21 0.88

BM-Al2O3-3% 300 1.95 1.48 1.08

BM-Al2O3-5% 316 2.20 1.67 1.21

BM-Al2O3-7% 325 2.46 1.70 1.24

BM-Al2O3-9% 337 2.56 2.01 1.64

Tg = Glass transition temperature Modulus50 = Modulus at 50 °CModulus150 = Modulus at 150 °CModulus250 = Modulus at 250 °C


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200 300 400 500 600 700 80060

70

80

90

100

Wei

ght (

%)

Temperature (°C)


Thermal Stability


N2, Ramp at 20 °C/min to 800 °C

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• Decomposition startedafter 450 °C.

• Temperature of 5%weight loss is above 540°C.

• Shape of curve suggestsone step degradationmechanism.

• Nanoparticlesincorporation improvedthe thermal stability ofpolyimide.


Polymer T1 (°C) T5 (°C) T10 (°C) R800 (%)

BM 449 542 572 61

BM-Al2O3-3% 451 545 575 63

BM-Al2O3-5% 453 545 575 64

BM-Al2O3-7% 453 545 576 65

BM-Al2O3-9% 453 552 580 68

T1 = Temperature at 1% weight lossT5 = Temperature at 5% weight lossT10 = Temperature at 10% weight lossR800 = Residue at 800 °C


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0 5 10 15 20 25 30 3597.0

97.5

98.0

98.5

99.0

99.5

100.0

Wei

ght (

%)

Time (min)


Isothermal study at 400 °C for 30 minutes


Air, Ramp at 50 °C/min to 400 °C

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• Polyimides can withstandelevated temperatures for acertain period of time.

• Pure polyimide (BM) showedonly 2.5% weight loss after30 minutes of isothermaltreatment at 400 °C.

• This was further reduced to1.9% at 9% loading of Al2O3

• Improvement in thermalstability in case ofPolyimide/Al2O3 compositesis evident from decrease inweight loss.


Polymer W15 (%) W25 (%) W35 (%)

BM 97.81 97.61 97.47

BM-Al2O3-3% 98.26 98.05 97.91

BM-Al2O3-5% 98.32 98.12 97.97

BM-Al2O3-7% 98.38 98.17 98.02

BM-Al2O3-9% 98.46 98.25 98.12

W15 = Weight percent after 15 minutesW25 = Weight percent after 25 minutesW35 = Weight percent after 35 minutes


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100 150 200 250 300 350 4000.00.10.20.30.40.50.60.70.8

tan(

d)

Temperature (°C)

BM BM-ZnO-3% BM-ZnO-5% BM-ZnO-7% BM-ZnO-9%

Polyimide/ZnO Nanocomposites


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• Pure polyimide displayedglass transition temperature(Tg) at 272 °C.

• Incorporation of ZnOnanoparticles increased theTg of polyimide matrix.

• Shape of curve at 9%loading suggests differentlevels of interactionsbetween nanoparticles andpolyimide matrix.

• At 9% loading, Tg wasincreased from 272 °C to360 °C.BM = polyimide (BTDA + MDA)

50 100 150 200 250 300 3500.00E+000

5.00E+008

1.00E+009

1.50E+009

2.00E+009

2.50E+009

E' (P

a)

Temperature (°C)


Storage Modulus


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• Modulus of pure polyimide(BM) above 1 GPa up to250 °C.

• It decreased sharply aroundglass transition temperature(Tg = 272 °C).

• ZnO nanoparticles improvedthe modulus of parentpolyimide matrix both atstart and around Tg.

• Modulus value at 50 °C wasincreased from 1.60 GPa to2.32 GPa at 9% loading ofnanoparticles.


Polymer Tg (°C) Modulus50

(109)

Modulus150

(109)

Modulus250

(109)

BM 272 1.60 1.21 0.88

BM-ZnO-3% 280 1.73 1.30 1.06

BM-ZnO-5% 319 1.87 1.39 1.08

BM-ZnO-7% 327 2.14 1.47 1.08

BM-ZnO-9% 360 2.32 1.70 1.26

Tg = Glass transition temperature Modulus50 = Modulus at 50 °CModulus150 = Modulus at 150 °CModulus250 = Modulus at 250 °C


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200 300 400 500 600 700 80060

70

80

90

100

Wei

ght (

%)

Temperature (°C)



Thermal Stability

N2, Ramp at 20 °C/min to 800 °C

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• ZnO nanoparticlesdecreased the thermalstability of polyimide.

• T5 was lowered to 460 °Cfrom 542 °C.

• ZnO concentration has noeffect on thermal behavior.

• Shape of curve suggestsone step degradationmechanism for purepolyimide and two stepsfor polyimide/ZnO.


Polymer T1 (°C) T5 (°C) T10 (°C) R800 (%)

BM 449 542 572 61

BM-ZnO-3% 393 459 504 62

BM-ZnO-5% 404 465 513 63

BM-ZnO-7% 404 468 517 63

BM-ZnO-9% 390 465 514 67

T1 = Temperature at 1% weight lossT5 = Temperature at 5% weight lossT10 = Temperature at 10% weight lossR800 = Residue at 800 °C


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0 3% 5% 7% 9%260

280

300

320

340

360

Tg (°

C)

Concenteration

Al2O3 ZnO

Comparison between PI/Al2O3 and PI/ZnO


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• Both types of nanoparticlesincreased glass transitiontemperature (Tg).

• At 9% loading, ZnOnanoparticles are moreeffective in increasing glasstransition temperature thanAl2O3 counterparts.

Storage Modulus (E’) at 50 °C

0 3% 5% 7% 9%

1.6

1.8

2.0

2.2

2.4

2.6

Mod

ulus

(Pa)

Concenteration

Al2O3 ZnO


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• Nanoparticlesincreased modulus.

• Addition of Al2O3changes is moreeffective than ZnO toimprove E’.

(GPa

)

0 3% 5% 7% 9%440

460

480

500

520

540

560

T5 (°

C)

Concenteration

Al2O3 ZnO

Thermal stability


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• Al2O3 nanoparticlesimproved the thermalstability at 5% weight loss.

• ZnO decreased thermalstability.

Conclusions

Nanoparticles can further improve modulus, glasstransition temperature and thermal stability, thuswith potential to provide further benefit inautomotive applications.

Thermogravimetric analysis (TGA) showedsubstantial thermal stability, thermaldecomposition started after 450 °C in some cases.

Isothermal studies with TGA showed thatpolyimides are capable to withstand at elevatedtemperatures for longer period of time.

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Conclusions

Incorporation of Al2O3 and ZnO nanoparticlesincreased the glass transition temperature andmodulus of polyimide.

At 9% loading, ZnO nanoparticles increased glasstransition temperature more than Al2O3, but Al2O3provided better modulus.

Polyimide/Al2O3 nanocomposites had higherthermal stability than polyimide alone.

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Acknowledgments

• University of Waterloo, Waterloo, Canada (NSERC Discovery Grantand experimental facilities)

• Quaid-i-Azam University, Islamabad, Pakistan (experimental facilities)

• Higher Education Commission of Pakistanfor funding of Ahmad Raza Ashraf under International ResearchSupport Initiative Program (for research visit as graduate student atUniversity of Waterloo, Canada) and Indigenous PhD FellowshipProgram at Quaid-i-Azam University, Islamabad, Pakistan.

Thank you!

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