Fluids transmission and thermal durability analysis of Miura-ori auxetic relief knits; the next generation wearable materials

Abstract

Knitted materials with superior thermal comfort attributes and cheap production costs are primarily utilized in leisurewear. Auxetic materials having biaxial stretch capabilities increase the propensity of knitted auxetic fabrics for size-changing clothing applications, such as maternity wear and growing kids' apparel, consequently supporting the sustainable development goal of responsible material consumption. Knitted auxetic fabrics based on Miura-ori fold geometries have been engineered with typically targeted clothing fibrous assemblies/yarns (polyester, cotton, and acrylic) and assorting different knitting parameters. Diagonal relief and hybrid square relief patterns with variable structural knitted cell (SKC) size proved to be a solution towards size and shape-changing clothing materials. Fluid transmission, heat retention, and durability evaluations were undertaken to determine the efficacy towards wearability of such auxetic materials. Varying structural porosities and the number of folds per unit area created properties discrepancy, governing different Poisson’s ratios and thermal attributes. Engineered foldable geometries exhibited about 10% to 40% increase in fluids transmissions than control plain rib fabrics. Quadratic thermal resistance enhancements of above 100% were noticed for auxetic fabrics and increasing SKC size enhanced thermal insulation. Influence of studied input variables was found statistically significant; fluid transmission had a p-value<0.05 for all material, SKC, and structure factors; heat retention was also significantly affected by material and SKC variation. The SKC size expansion promoted auxeticity up to optimum size of 9×9. Corresponding associations estimation using bubble plot analysis revealed positive correlations between fluid transmissions and durability attributes; however, an increase in fluid transmission compromised the heat retention of materials.