Journal of Materials Science

, Volume 32, Issue 21, pp 5725–5736 | Cite as

Microscopic examination of the microstructure and deformation of conventional and auxetic foams

  • N CHAN
  • K. E EVANS


Auxetic materials have a negative Poisson’s ratio, that is, they expand laterally when stretched longitudinally. One way of obtaining a negative Poisson’s ratio is by using a re-entrant cell structure. Auxetic foam was fabricated from a conventional polymeric foam. Assuming similar mechanical properties for the solid material comprising the foams, the principle variable affecting the properties of the foam is the geometry of the cells. This means that the unusual mechanical properties of auxetic foams are attributed to the deformation characteristics of re-entrant microstructures. In this paper, the results of optical- and scanning electron-microscopic studies of the geometrical parameters for the different foams examined are presented. Examples of the microstructural deformation mechanisms observed are also presented. Comparison between the conventional foams and their auxetic conversions are also made.


Foam Urethane Urethane Foam Rise Direction Auxetic Material 


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Copyright information

© Chapman and Hall 1997

Authors and Affiliations

  • N CHAN
    • 1
  • K. E EVANS
    • 2
  1. 1.Institute of Aeronautics and AstronauticsNational Cheng Kung UniversityTainanTaiwan
  2. 2.School of Engineering, Harrison Engineering BuildingThe University of ExeterExeterUK

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