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Dr. James Elliott CPhys CSci MInstPhys

Dr. James Elliott, CPhys CSci MInstPhys

University Reader (Materials Science)

College Lecturer and Director of Studies (Fitzwilliam College)

James Elliott is available for consultancy.


Office Phone: +44 1223 335987

Biography:

2002-date Fitzwilliam College, University of Cambridge.
Elected as Fellow, Director of Studies and College Lecturer in Materials Science
2001-date Department of Materials Science & Metallurgy, University of Cambridge.
University Lecturer in Materials Modelling
1998-2001 Polymer Group, University of Cambridge.
Postdoctoral Research Associate "Packing of fibre and filler particles in polymer composites" (supervised by Profs. Alan Windle and Anthony Kelly).
1995-98 University of Bristol : PhD in Polymer Physics
"X-ray diffraction and computer modelling of perfluorinated ionomer membranes"
Supervised by Dr. Simon Hanna
1992-95 University of Cambridge : MA Honours in Natural Sciences
Part II : Physics & Theoretical Physics

Research themes

Energy Storage:

Multiscale materials modelling

Polymer electrolytes for fuel cells and batteries

Nanocomposite materials

Materials and Chemistry:

Carbon nanotubes

Electrical percolation

Mechanical property enhancement

Research Interests

Multiscale Materials Modelling - polymer electrolytes for fuel cell and battery applications, carbon nanocomposites with enhanced mechanical, electrical and thermal properties, and biomimetic composite materials.

Pharmaceutical Materials Science - packing, flow and compaction of pharmaceutical powders for tabletting and inhalation delivery, in situ imaging of particle motion during compaction, and comparison with finite element modelling.

Key Publications

 

Wu, D., Paddison, S.J., Elliott, J.A. “A comparative study of the hydrated morphologies of perfluorosulfonic acid fuel cell membranes with mesoscopic simulations”, Energy Environ. Sci., 1, 284-293 (2008). DOI:10.1039/b809600g

Paddison, S.J. and Elliott, J.A. “Molecular modeling of the short-side-chain perfluorosulfonic acid membrane” J. Phys. Chem. A, 109, 7583-7593 (2005). DOI:10.1021/jp0524734

Perfluorosulphonate ionomer membranes are a crucial component of fuel cell technologies, including those using hydrogen, methanol and liquid electrolytes, but remain prohibitively expensive for widespread use. Using a combination of mesoscale and quantum mechanical modelling techniques, we were able to show that a connected network of ionic groups is necessary to allow proton transport under conditions of minimal hydration, allowing fuel cells to run at higher operating temperatures. We also explored the effects of changes in side-chain chemistry on the membrane morphology on the micrometre scale.

Elliott, J.A., Sandler, J.K.W., Windle, A.H., Young, R.J. and Shaffer, M.S.P. “Collapse of single-wall carbon nanotubes is diameter dependent”, Phys. Rev. Lett., 92, 095501 (2004). DOI:10.1103/PhysRevLett.92.095501

We resolved a long-standing controversy concerning the nature of structural phase transitions in single-wall carbon nanotubes under pressure. Recently, high-resolution electron microscopy studies have since confirmed that individual tubes within a aggregated bundle collapse according to their diameter. Since carbon nanotubes are increasingly used in composites, high-strength fibres and other applications where mechanical properties are crucially important, the paper’s theoretical predictions have had a wide reaching industrial and practical impact on experimental programmes developing new types of material.

Rahatekar, S.S., Hamm, M., Shaffer, M.S.P. and Elliott, J.A. “Mesoscale modelling of electrical percolation in fibre-filled systems” J. Chem. Phys., 123, 134702 (2005). DOI:doi:10.1063/1.2031147

As well as their applications in mechanical reinforcement of polymers, carbon nanotubes can imbue electrical conductivities of the order of 0.01 S/m with loading fractions of less than 0.1 wt%. To explain this phenomenon, we modelling the percolation behaviour of carbon nanotube networks using mesoscale computer simulations, and developed algorithms to determine their impedance to electrical current as a function of aspect ratio, spatial distribution and orientations of the nanotubes. The results were used in a US Army funded research programme to develop conductive thermoplastic textile fibres.

Wu, C.-Y., Ruddy, O.M., Bentham, A.C., Hancock, B.C., Best S.M. and Elliott, J.A. “Modelling the mechanical behaviour of powders during compaction” Powder Tech., 152, 107-117 (2005). DOI:10.1016/j.powtec.2005.01.010

Compaction of granular materials has widespread industrial applications, from pharmaceutical tabletting to powder metallurgy and sintering of ceramic compacts. Using a combination of finite element modelling and compaction using an instrumented die, we established for the first time that the main reason for ‘capping’ failure of flat-faced cylindrical tablets during compression is shear failure during elastic decompression of the tablet during unloading. The results have been directly incorporated in Pfizer formulation development programmes in the UK and US.

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