Graphene-reinforced elastomers for demanding environments

Transcription

1 Graphene-reinforced elastomers for demanding environments Robert J Young, Ian A. Kinloch, Dimitrios G. Papageorgiou, J. Robert Innes and Suhao Li School of Materials and National Graphene Institute The University of Manchester Oxford Road, Manchester M13 9PL, UK

2 Different forms of carbon Diamond Graphite

3 Graphene World s first 2D solid Single layer of carbon atoms Young s Modulus = 1.05 TPa Exfoliated in Manchester from graphite using Scotch tape (Sarah Haigh, 2012) 2 nm (Novoselov, Geim et al, Science 2004) High resolution TEM

4 Graphene-based nanocarbons Graphene C 60 Nanotubes Graphite A. K. Geim, K. S. Novoselov, Nature Materials, 6, (2007)

5 Morphological Thinnest imaginable material one atom thick Highest surface area 2630 m 2 /g Transparent to light (97.7 %) Mechanical Stiffness = 1 TPa Strength = 130 GPa Graphene superlatives Electrical and thermal Record thermal conductivity (6000 W/m/K) Highest current density at room temp (million times of that in copper) Highest intrinsic mobility (100 times more than Si) Lightest charge carrier (Dirac fermions) Longest mean free path at room temp (microns) Chemical Relatively easily functionalised & processable Barrier Impervious to even Helium but can have controlled porosity

6 UK National Graphene Institute (NGI) Collaborative Graphene Research Facility, University of Manchester 70M investment for the commercialisation of graphene (UK government and EU Regional Development Fund) Graphene Engineering Innovation Centre under construction 60M investment from Masdar and HEFCE

7 The National Graphene Institute UK government support George Osborne Visit of President Xi of China 2015

8 I billion over 10 years F A key benefit, especially in the near term, is multi-functionality, e.g. in OLED packing it is transparent, an oxygen barrier, flexible, and conductive.

9 Graphene in reality Monolayer Bilayer >10 layer Graphite Nanoplatelets Graphene oxide Known since 1850 s, 25 to 30 % O - Can be reduced

10 Raman spectroscopy The technique of choice for the characterisation of graphene laser beam scattered light specimen Inelastic scattering of light Laser spot size down to 1 µm Spectra obtained for many non-metallic materials Particularly useful for nanomaterials Large stress-induced band shifts (stress sensing!)

11 Mechanically-exfoliated graphene Optical micrograph Raman spectra Mechanically-Cleaved Graphene Intensity (a.u.) G 2D >5 Layers 3 Layers Layers 1 Layer Raman Wavenumber (cm -1 ) Raman spectrum can be obtained from a single layer of carbon atoms Raman spectroscopy allows the number of layers to be counted

12 Deformation of a graphene monolayer Monolayer Optical micrograph Raman 2D band downshifts with strain (b) 0.4% Intensity (A.U.) 0.2% 0% (Advanced Materials, 22 (2010) ) Raman Wavenumber (cm -1 )

13 Deformation of a graphene monolayer Single graphene layer on the surface of a PMMA beam Uncoated First Loading High 2D band shift rate implies a high Young s modulus for graphene I TPa 2D Position (cm -1 ) Shift rate of graphene 2D = -60 cm -1 /% strain 2620 Graphene/polymer interface intact (Advanced Materials, 22 (2010) ) Strain (%)

14 Mapping of axial strain across a single graphene flake Strain in graphene e g = e m 1 2x cosh ns l cosh( ns) where n = E g 2G m ln( T / t) Shear lag theory Critical length 3 µm Stress direction The length factor, η l, can be determined from the critical length (ACS Nano, 5 (2011) ).

15 Graphene composites

16 PMMA-graphene composites - preparation Graphite Gram scale production of graphene using electrochemical exfoliation(uom IP). Melt processing of composites using standard compounding and injection moulding.

17 Young modulus (GPa) Graphene composites Injection moulded PMMA-graphene composites Mechanical testing of PMMA graphene nanocomposites Loading (vol.%) <5 µm flake 20 µm flake Larger flakes give better reinforcement Loading (wt.%) (Valles, Abdelkader, Young, Kinloch, Faraday Discussions 2014, 173, )

18 Review Graphene/elastomer nanocomposites Dimitrios G. Papageorgiou, Open access - DOI: /j.carbon

19 Graphite-oxide/natural-rubber nanocomposites Stress-strain curves show significant reinforcement Latex Premixing Two-roll Mill Latex premixing seems to lead to better properties than conventional processing Potts JR, Shankar O, Murali S, Du L, Ruoff RS. Latex and two-roll mill processing of thermally-exfoliated graphite oxide/natural rubber nanocomposites. Composites Science and Technology. 2013;74(0):

20 Graphene-elastomer strain sensors Rubber bands swelled and infiltrated with graphene nanoplatelets Electrically conductive Resistance changes with strain body motion sensor Boland CS, Khan U, Backes C, O Neill A, McCauley J, Duane S, et al. Sensitive, High-Strain, High-Rate Bodily Motion Sensors Based on Graphene Rubber Composites. ACS Nano. 2014;8(9):

21 Graphene/natural-rubber nanocomposites Natural rubber compounded with different phr of graphene nanoplatelets Scanning electron micrographs of the component materials Particle diameters M5 5 µm M15 15 µm M25 25 µm (all 7 nm thick)

22 Graphene/natural-rubber nanocomposites Natural rubber compounded with different phr of graphene nanoplatelets Scanning electron micrographs of the compounds

23 Graphene/natural-rubber nanocomposites Natural rubber with different phr of M15 graphene nanoplatelets 18 Significant reinforcement is found - increase in stiffness Stress-strain curves NR15 NR10 NR5 Stress (MPa) Increasing graphene content NR20 NR 4 Suhao Li (2016) Unpublished data Strain (mm/mm)

24 Graphene/natural-rubber nanocomposites Natural rubber with different phr of graphene nanoplatelets in toluene Significant solvent uptake, swelling and mass increase is found Final mass, M, decreases with graphene loading 6 M t /M 0 M t /M 0 versus t 1/2 1.2 M t /M M t /M versus t 1/ M15 5phr M15 10phr M15 15phr 2 M 0.4 M15 20phr NR t 1/2 /hr 1/ t 1/2 /hr 1/2 Suhao Li (2016) Unpublished data Gravimetric Determination of the Diffusion Characteristics of Polymers using Small Specimens A.J. Cervenka, R.J. Young, K. Kueseng, Journal of Polymer Science: Part B: Polymer Physics, 42, (2004)

25 Graphene/natural-rubber nanocomposites Natural rubber with different phr of graphene nanoplatelets Significant increases in thermal conductivity is found Depends upon particle size 0.35 Thermal conductivity (W/mK) M5 M15 M25 Suhao Li (2016) Unpublished data 0 NR 5 phr 10 phr 15 phr 20 phr

26 Graphene/nitrile-rubber nanocomposites Nitrile rubber with different phr of graphene nanoplatelets Significant reinforcement is found - increase in stiffness and strength 9 Stress-strain curves Stress (MPa) Increasing graphene content NBR20 NBR NBR15 NBR5 NBR Suhao Li and J Robert Innes (2016) Unpublished data Strain (mm/mm)