Tribological behaviour of carbon filled hybrid UHMWPE

composites in water

Hari Shankar Vadivel, Arash Golchin, Nazanin Emami

Biotribology group, Division of Machine Elements,

Luleå University of Technology, Sweden

IntroductionMove towards water lubrication

• Water a better option than EALs(Environmentally AdaptedLubricants)• Non toxic, readily available (especially

in aqueous envt.)

• Use of water as lubricantrequires use of special materialsfor shafts, bearing, etc.• Prevalence of boundary lubrication

3

http://www.w-program.nu/filer/exjobb/Stina_%C3%85strand.pdf

IntroductionPolymer Based Materials (PBMs)

• PBMs are good candidates for use in boundary lubricated conditions [1-3]– Thermoplastics

– Can follow the substrate deformations

– Self-lubricating property

– PLA, PPS, PE, etc.

• Drawbacks – Viscoelastic deformation, water absorption

– High wear rates

4

www.thordonaustralia.com

www.zimmer.com

[1] Clarke & Allen, , The water lubricated, sliding wear behaviour of polymeric materials against steel, Tribology International, 24(2), 109-118,1991 .[2] Rymuza, Tribology of polymers, Archives of Civil and Mechanical Engineering, 7(4), 177-184, 2007.[3] Brostow, Tribology of polymers and Polymer based composites, Journal of Materials Education Vol.32 (5-6): 273 – 290, 2010

5

Improvement pathways

Cross linking by radiation

Vitamin E

Polymer Blending

Fillers/

composites

Improvement pathways

• Carbon based• CNTs• Graphene

• Metal particles• Fibers

Hybrid/Multiscale Composites

• Combine both micro and nanoreinforcements

– Ability to functionalize the fillers,Possibility to tailor properties, synergisticeffect.

• Micro and nano HA in UHMWPE combineto give better mechanical properties thaneither of them alone [10]

• Sustained macroscale super-lubricity in combination of Graphene and Nanodiamonds [11]

6[10] Kang et al, Mechanical properties study of micro- and nano-hydroxyapatite reinforced ultrahigh molecular weight polyethylene composites, Journal of App. Poly. Sci , 133(3), 1-9, 2016[11] Berman et al., 2015, Macroscale superlubricity enabled by graphene nanoscroll formation , Research, Vol 348 Issue 6239

• Semi crystalline thermoplastic polymer withMolecular weight usually between 2 and 6million g/mol• High molecular weight imparts toughness

• Superior performance in load bearingsystems where water and non oil basedlubrication is used [4,5] and also inbiomedical applications [7,8]

• Excellent low-speed performance ofRubber/UHMWPE alloy as material formarine stern tube bearings[6]

UHMWPEUltra High Molecular weight Polyethylene

n > 100,000.

7[4] Golchin et al, Tribological behaviour of polymeric materials in water-lubricated contacts, Proc. of the Institution of Mech. Eng. Part J-Journal of Eng. Trib., 227(8),811-825, 2013.[7] Affatato et al, Advanced biomaterials in hip joint anthroplasty, Composites Part B: Engineering, 83, 276-283, 2015.[8] Baena et al, Wear Performance of UHMWPE and Reinforced UHMWPE Composites in Arthroplasty Applications: A Review, Lubricants 2015, 3, 413-436, 2015

1. To design Multiscale composites based on UHMWPE

2. To experimentally investigate the synergistic effect of fillerson tribological performance and properties

Research objectives

8

Materials

Designation Composition (wt%)

GO ND SCF

UHMWPE Pure UHMWPE

0.5% GO 0.5 - -

0.5% ND - 0.5 -

10% SCF - - 10

GO + ND + SCF 0.5 0.5 10

GO + ND 0.5 0.5 -

GO + SCF 0.5 - 10

ND + SCF - 0.5 10

1% GO 1 - -

1% ND - 1 -

Particle Average size

Graphene Oxide (GO)

Length/width0.7 – 4 μmProfile0.7-1.2 nm

Nanodiamonds(ND)

Ø 5 nm

Short Carbon Fibers (SCF)

length 100 μm, Ø 7 μm

UHMWPE Ø 30 μm

9D. Berman, A. Erdemir and A. V. Sumant, “Graphene: a new emerging lubricant,”, Materials today, vol 17(1), 31-42, 2014Ullah et al., Reinforcing Effects of Modified Nanodiamonds on the Physical Properties of Polymer-Based Nanocomposites: A Review, Polymer-Plastics Technology and Engineering, 54: 861–879, 2015Chukov et al., Investigation of structure, mechanical and tribological properties of short carbon fiber reinforced UHMWPE-matrix composites, Composites Part B: Engineering, 76, 79-88, 2015

Sonication in ethanol

UHMWPE + Filler

Ball MillingDry/wet

DryingComposite powder

Direct Compression Molding

Manufacturing Process

10[13] E. Enqvist, Carbon Nanofiller Reinforced UHMWPE for Orthopaedic Applications , LTU, 2013

• Pin on disc tribo tests– Time : 20h

– Sliding distance ~ 9400 m

– Counter Surface : Inconel 625 discs

– Load : 88 N

– Contact pressure – 5 MPa

• SEM

• Wettability

• Thermal characterisation– DSC

– TGA

11

Measurements and analyses

DiscPolymer pin

LoadWaterLVDT

a = 4.2mm

a

Unfilled UHMWPE-pre milling

12

SEM

Unfilled UHMWPE-post milling

50 µm 50 µm

GO + ND + SCF

Post milling

50 µm

X ray Microtomography

Friction Coefficient (μ)

14

• Reduction of μ with addition of GO and ND

• 140 μm PE + GO/ND showed higher FC [14,15]

• GO+ND+SCF displays low μ– 21% reduction compared to

unfilled UHMWPE

Fric

tio

n c

oef

fici

en

t (μ

)

0

0,04

0,08

0,12

0,16

0,2

[14] Golchin et al., An investigation into tribological behaviour of multi-walled carbon nanotube/graphene oxide reinforced UHMWPE in water lubricated contacts, Trib. Int. 95 (2016) 156–161. [15] Villain., Nanodiamond/Ultra-High Molecular Weight Polyethylene Composites for Bearing Applications, report, LTU, 2015

Specific wear rate (SWR) of polymer composites

15

• Even though 10% SCF showshigh μ , wear rate is not - SCFcan protect the polymer fromabrasion.

• Low value of GO+ND+SCF –15% decrease from unfilledUHMWPE

• 140 μm UHMWPE+GO hashigher wear rate [14]

[14] Golchin et al., An investigation into tribological behaviour of multi-walled carbon nanotube/graphene oxide reinforced UHMWPE in water lubricated contacts, Trib. Int. 95 (2016) 156–161.

0

0,4

0,8

1,2

1,6

2

Spec

ific

we

ar r

ate

10

-6 m

m3

/Nm

Wear tracks

16200 µm200 µm

SCF+UHMWPE

200 µm200 µm

GO+UHMWPE ND+UHMWPE

GO + ND + SCF + UHMWPE

Wettability

• Hydrophobicity of UHMWPE is an important factor in low wear rate in metal-on-polymer contacts [19]

• All fillers used tend toincrease hydrophobicity

• 11% increase in contactangle for GO+ND+SCF

17[19] A. Golchin, G. Simmons, S. Glavatskih, B. Prakash, Tribological behaviour of polymeric materials in water-lubricated contacts, proc. of the inst. of mech. eng-. part j-journal of engineering tribology 227 (8) (2013) 811–825.

Sl. No.

Sample Mean Contact angle

1 Pure UHWMPE 81.4

2 0.5 wt% GO 82.6

3 1 wt% GO 85.9

4 0.5 wt% ND 89.3

5 1 wt% ND 86.8

6 10 wt% SCF 88.3

7 GO + ND + SCF 90.1

8 GO + ND 88

9 GO + SCF 90.4

10 ND + SCF 89.5

18

Contact angle vs. μ

• Higher the contactangle, lower the μ– asdesired.

• GO+ND+SCF exhibitslow wear and lowest μwith good hydrophobicnature.

Differential Scanning Calorimetry

• Crystallinity not affected bymanufacturing process

• Similarly, no effect on meltingpoint

• Note: Crystallinity was improvedwith the addition of smallamount of GO and ND – act asnucleation centers [22,23]

• SCF inhibits chain formation[17]

19

0

10

20

30

40

50

60

70

Cry

stal

linit

y (%

)

[ [17] Enqvist et al., Nanodiamond reinforced uhmwpe: a comparison of dry and wet ball milling manufacturing, Tribology - Materials, Surfaces & Interfaces Volume 8, Issue 1, 2014

Thermo-gravimetric analysis

• Composite GO+ND+SCF has the most delayed temperature points

• Delayed oxidation and consequent degradation [18]

20

Thermal stability of polymers

[18] R. J. M. John M. Chalmers, Chapter 10 polymer degradation and oxidation: An introduction, in: Comprehensive Analytical Chemistry, Wiley, 2008, pp. 387–450.

Weight left Label Observation

100 % T0 point just before any temperaturechanges start to occur

95 % T1 temperature for maximumsample mass

90% T2 end of the gradual weight loss

5% T3 rapid degradation ends

≤ 1% T4 sample has achieved completedecomposition

Composite Temperature (˚C) ± Standard deviation

T0 T1 T2 T3 T4

UHMWPE 167±5.5 244±2.8 437±12.1 486±1.41 560±1.6

GO+ND+SCF 210±2.4 248±9.4 426±4 489±10.3 582±4.3

• Manufacturing process has beenoptimized.

• Use of smaller PE particles has a positiveinfluence on performance and properties.

• Inclusion of fillers did not affectcrystallinity

• Thermal stability of polymer compositeswas improved

• Hybrid composite has been prepared andshown to perform well. GO+ND+SCF has

– good hydrophobic nature - 11%increase

– low μ - 21% less than unfilledUHMWPE

– low wear - 15% reduction comparedto unfilled UHMWPE

Concluding remarks

21

22

Thank youContact :

hari.vadivel@ltu.seLuleå University of Technology

This project was carried out within TRIBOS master (European Master MSc. degree in tribology)

1. Clarke & Allen, , The water lubricated, sliding wear behaviour of polymeric materials against steel, Tribology International, 24(2), 109-118,1991 .

2. Rymuza, Tribology of polymers, Archives of Civil and Mechanical Engineering, 7(4), 177-184, 2007.

3. Brostow, Tribology of polymers and Polymer based composites, Journal of Materials Education Vol.32 (5-6): 273 – 290, 2010

4. Golchin et al, Tribological behaviour of polymeric materials in water-lubricated contacts, Proceedings of the Institution of Mechanical Engineers Part J-Journal of EngineeringTribology, 227(8),811-825, 2013.

5. Markus & Allen, The Sliding Wear of Ultrahigh Molecular-Weight Polyethylene in an Aqueous Environment , Wear 178, 17-28, 1994.

6. Hong-ling Qin, Xin-cong Zhou, Xin-ze Zhao, Jing-tang Xing, Zhi-ming Yan, A new rubber/UHMWPE alloy for water-lubricated stern bearings, Wear, Volume 328, 2015, Pages 257-261, ISSN 0043-1648,

7. Affatato et al, Advanced biomaterials in hip joint anthroplasty, Composites Part B: Engineering, 83, 276-283, 2015.

8. Baena et al, Wear Performance of UHMWPE and Reinforced UHMWPE Composites in Arthroplasty Applications: A Review, Lubricants 2015, 3, 413-436, 2015

9. Sattari et al., Interphase evaluation and nano-mechanical responses of UHMWPE/SCF/nano- SiO2 hybrid composites: A Review, Polymer Testing 38 (2014) 26-34, 2014

10. Kang et al, Mechanical properties study of micro- and nano-hydroxyapatite reinforced ultrahigh molecular weight polyethylene composites, Journal of Applied Polymer Science ,133(3), 1-9, 2016

11. Berman et al., 2015, Macroscale superlubricity enabled by graphene nanoscroll formation, Research, Vol 348 Issue 6239

12. D. Berman, A. Erdemir and A. V. Sumant, “Graphene: a new emerging lubricant,”, Materials today, vol 17(1), 31-42, 2014

13. E. Enqvist, Carbon Nanaofiller Reinforced UHMWPE for Orthopaedic Applications, Thesis, LTU, 2013

14. Golchin et al., An investigation into tribological behaviour of multi-walled carbon nanotube/graphene oxide reinforced UHMWPE in water lubricated contacts, Tribology International95 (2016) 156–161.

15. Villain., Nanodiamond/Ultra-High Molecular Weight Polyethylene Composites for Bearing Applications, report, LTU, 2015

16. Enqvist et al., Nanodiamond reinforced uhmwpe: a comparison of dry and wet ball milling manufacturing, Tribology - Materials, Surfaces & Interfaces Volume 8, Issue 1, 2014

17. Suner et al., Ultra High Molecular Weight Polyethylene/Graphene Oxide Nanocomposites: Thermal, Mechanical and Wettability Characterisation, Composites Part B Engineering2015;78(1):185-191

18. R. J. M. John M. Chalmers, Chapter 10 polymer degradation and oxidation: An introduction, in: Comprehensive Analytical Chemistry, Wiley, 2008, pp. 387–450.

19. A. Golchin, G. Simmons, S. Glavatskih, B. Prakash, Tribological behaviour of polymeric materials in water-lubricated contacts, proceedings of the institution of mechanicalengineers part j-journal of engineering tribology 227 (8) (2013) 811–825.

20. N. W. Khun, H. Zhang, L. H. Lim, C. Y. Yue, Tribological properties of short carbon fibers reinforced epoxy composites, Friction (2014) 226–239

References

23