Auxetic systems

Materials with NPRs have superior properties when compared with conventional materials (Choi and Lakes 1996 Wang and Lakes 2002 Scarpa et al. 2005 Bezazi and Scarpa 2009). For example, upon impact, the material in auxetic systems flows toward the point of impact (Chan and Evans 1998) resulting in a more dense system. This is in opposition to conventional materials where the material tends to flow away from the point of impact resulting in a less dense system. This means that auxetic materials tend to show a higher impact resistance (Alderson 1999) (see Figure 10.2a). This feature is potentially applicable in personal protection equipment such as... 

Auxetic systems may also be used as smart filters where the pore size of the filter can be adjusted by changing the tensile stress applied to the filter. Ideal candidates for this type of filters at the molecular level include auxetic zeolites because of their open geometry (Alderson et al. 2000, 2005a,b Grima 2000). 

Alderson, A., Davies, P. J., Evans, K. E., Alderson, K. L. and Grima, J. N. Modelling of the mechanical and mass transport properties of auxetic molecular sieves An idealised inorganic (zeolitic) host-guest system. Mol. Simid. 31, 2005a, 889-896. 

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