University of Malta Dr. Joseph N. Grima
   B.Sc.(Malta), Ph.D.(Exon), M.Inst.P., C.Phys., MRACI, C.Chem. 
   Hon. Fellow (University of Exeter, UK)
   Chartered Chemist & Physicist
   Lecturer in Chemistry (University of Malta)

[ Dr. JN GRIMA | TEACHING | RESEARCH | PUBLICATIONS | AUXETIC MATERIALS  | OTHER LINKS ]
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Modelling materials with negative Poisson's ratios

    Materials with a negative Poisson's ratios (auxetic) exhibit the very unusual and intersting property of becoming wider when stretched and thinner when compressed. My research entails the modelling and simulation of the mechanical properties of materials in an attempt to discover or design materials with this unusual property. Several new auxetic nano/micro/macrostructures have been invented and explored in detail.
    Particularly interesting results include the discovery of negative Poissonís ratios in the zeolite class of materials, the design of various networked polymeric auxetics and, the development of models for predicting the mechanical properties of auxetic foams and of microporous polymers. Some of these discoveries have a number of very important technical implications (e.g. the discovery of negative Poissonís ratios in zeolites which opens many new possibilities towards the use of zeolites as tunable filters).


Recent publications:

(a) Printed publications:

  1. J.N. Grima and K.E. Evans, Rotating squares with negative Poisson's ratios, J. Mat. Sci. Lett., 19 (2000) p.1563-1565.
  2. J.N. Grima and K.E. Evans, Self expanding networks, Chem. Comm., (2000) p.1531-1532.
  3. C.W. Smith, J.N. Grima and K.E. Evans, A novel mechanism for generating auxetic behaviour in reticulated foams: Missing rib foam model.Acta Materiala, 48 (2000) p4349-4356.
  4. J.N. Grima, R. Jackson, A. Anderson, K.E. Evans, Do zeolites have negative Poisson's ratios?  Adv. Mater., 12 (2000) p. 1912-1918.. 
  5. C.W. Smith, J.N. Grima, B.D. Caddock, R.J. Wootton and K.E. Evans, Microstructures producing negative Poisson's ratios: Experiment and models, SEM Theoretical, Experimental and Computational Mechanics Preprints (1999) p.184-187.
  6. J.N Grima and K.E. Evans, Networked polymers with negative Poisson's ratios, ACS Polymeric Materials Science & Engineering Preprints, 83 (2000) p. 367-368.


(1) Reviewed by the Philadelphia section of the Society of Plasitcs Engineers, USA, in Philadelphia Plastics Press, Nov. 2000 - "... this paper describes how an arrangement of squares can lead to auxetic behaviour. ... I expect to see several new patents from the Philadelphia Section members two to ten years from now because of this important revelation."

(2) Selected as Hot Paper by editors of Chemical Communications

(b) Papers presented at international conferences:

  1. J.N Grima and K.E. Evans, The modelling and synthesis of auxetic materials, Paper presented at the 3rd Materials Chemistry conference, Exeter (UK), July 1997 (P125).
  2. C.W. Smith, J.N. Grima, L.G. Bridger, B.D. Caddock, R.J. Wootton and K.E. Evans, Microstructures producing negative Poisson's ratios: Experiment and models, Paper presented at the Spring Conference of the Society for Experimental  Mechanics, Cincinnati (USA), June 1999.
  3. J.N Grima and K.E. Evans, Molecular auxetic materials, Paper presented at the 4th Materials Chemistry conference, Dublin (Ireland), July 1999 (B2.1).
  4. J.N Grima, A. Alderson and K.E. Evans, Zeolites with negative Poisson's ratios, Paper presented at the 4th Materials Chemistry conference, Dublin (Ireland), July 1999 (P81).
  5. J.N. Grima and K.E. Evans, Networked nanostructured polymers with negative Poisson's ratios, Paper accepted for publication at the Materials Research Society Spring Conference, San Francisco (USA), April 2000.
  6. J.N. Grima, A. Alderson and K.E. Evans, Zeolites with negative Poisson's ratios, Paper presented at 220th ACS National Meeting (Inorganic Division), Washington DC, August 2000.
  7. J.N Grima and K.E. Evans, Networked polymers with negative Poisson's ratios, Paper presented at 220th ACS National Meeting (PMSE Division), Washington DC, August 2000.
  8. J.N. Grima, A. Alderson and K.E. Evans, Modelling zeolites with negative Poisson's ratios, Paper presented at 2nd Inorganic Materials Conference, Sta. Barbara, USA, September 2000.
  9. A. Alderson, J. Rasburn, J.N. Grima and K.E. Evans, Auxetic polymeric filters: Tunable filters displaying enhanced de-fouling and pressure-compensation properties. Paper accepted for publication at the Polymer '01 conference, Bath, UK, March 2001. 

(c) Others:

  1. J.N Grima, Auxetic behaviour through rotating triangles, SOE Departmental Seminar, University of Exeter, UK. September 1998.
  2. J.N Grima, Negative Poisson's ratios at the molecular level, Materials Research Group Seminar, University of Exeter, UK. July 1999.
  3. J.N. Grima, New Auxetic Materials - Vols. 1 & 2, Ph.D. Thesis, University of Exeter, UK. March 2000.

[ UNIVERSITY OF MALTA | FACULTY OF SCIENCE | DEPARTMENT OF CHEMISTRY ]
[ UNIVERSITY OF EXETER, UK | DEPARTMENT OF ENGINEERING  ]

E-mail me at jgri1@um.edu.mt http://staff.um.edu.mt/jgri1