Cross-tuck honeycomb based 3D weft knitted auxetic structures with enhanced adaptability/size changing capability & thermo-physiological comfort properties

Abstract

Auxetic structures, distinguished by their unusual negative Poisson’s ratio, have attracted a lot of interest because of their remarkable mechanical properties and wide range of possible applications. The qualities of auxetic structures are superior to those of conventional ones like (shear resistance, formability, energy absorbance, and robust fracture strength). Auxetic structures have the unique property of expanding in one dimension when subjected to stretching in another. In this research, weft-knit auxetic structures of varying Negative Poisson’s ratio (NPR) have been developed and tested for wearability and mechanical properties. Using a Stoll flat knitting machine with nylon, polyester, acrylic, and cottonari yarns with base structure of the cross-tuck design, three distinct auxetic weft-knitted structures were created. Negative Poisson’s ratio strain curves of the developed fabrics have been plotted; except for nylon, all fabrics exhibit a negative passion ratio (NPR). At 30 mm of extension, polyester shows its highest NRP value (-0.6), and the NPR decreases with increasing strain in the longitudinal direction. Comfort performance is measured quantitatively by taking several objective measurements, including air permeability, thermal conductivity, and the rate at which moisture vapor is transmitted through the fabric. The results showed that nylon and polyester yarn structures have a higher value of air permeability than cotton and acrylic yarn structures, while acrylic yarn structures have the highest thermal resistance values compared to the other materials.

Keywords:

• Future textiles
• smart materials
• auxetic structures
• negative Poisson ratio (NPR)
• mechanical properties

Disclosure statement

No potential conflict of interest was reported by the authors.