Quasi Tri-Axial Method for the Fabrication of Optimized Polyurethane Auxetic Foams

This paper describes the fabrication of polymeric auxetic foam using a quasi tri-axial compression method. In this method, the conversion process is executed by applying a quasi tri-axial compression on conventional closed-cell polyurethane foams. In order to achieve optimum auxetic characteristics, the densification points in various directions are evaluated. In addition, the heating time of the compressed foam is also determined and applied to minimize the residual stress due to the volumetric compression. It leads to the fabrication of auxetic foams with achievable maximum re-entrancy and minimum collapsed cells without surface creasing. The results also show that the optimized auxetic foam exhibits isotropic behavior compared to its pre-cursor foam as verified by the morphological analysis. The produced foam has all the desired properties of auxetic foams. The auxetic foam with a negative Poisson's ratio may be have great potential as the supplementary materials in energy absorption and structural applications.