Abstract


Auxetics are unique materials that exhibit negative Poissons ratio i.e. which expand laterally when extended axially. This is due to the molecular reorientation at micro molecular level and structural deformations at macro scale. These auxetic textiles possess high indentation and fracture resistance, shear modulus and dynamic properties. Producing fibers with auxetic properties involves the modification in polymer preparation stage followed by spinning process. Auxetic fabric structures are produced in major by knitting and are achieved by suitably choosing the structure of fabric. These textiles have potential applications in defense and protective fields and in major other areas which require its properties.


Introduction


Auxetics are materials that have a negative Poisson's ratio. Elastic characteristics of Engineering materials follows the effect proposed by Simeon Poisson, stating the slight movements between molecules and the stretching of molecular bonds within the material lattice to accommodate the stress. When the bonds elongate in the stress direction, they shorten in the other directions. This behavior multiplied millions of times throughout the material lattice is what drives the phenomenon.


When a sample of material is stretched in one direction, it tends to contract (or rarely, expand) in the other two directions. Conversely, when a sample of material is compressed in one direction, it tends to expand (or rarely, contract) in the other two directions. Poisson's ratio (ν) is a measure of this tendency.



Read Full Article



The authors are Third Year B.Tech Fashion Technology students from PSG College of Technology Coimbatore