Mechanical Performance of Hemp-Containing Denim Fabrics with Core-Engineered Weft Yarns

The mechanical performance of hemp-containing denim fabrics depends not only on fibre selection but also on how fibre composition is translated into yarn and fabric structure. Substituting part of the cotton warp with hemp is one possible step toward more sustainable denim production, but this study makes no independent sustainability claim (i.e., no life-cycle assessment was performed) and instead focuses solely on mechanical behaviour. This study comparatively evaluated eleven denim fabrics produced with 100% cotton or cotton/hemp-blended (69/31) warp yarns and different rigid, elastane-core and PET/PTT+elastane dual-core weft yarns. Grab tensile strength and tear strength were assessed in warp and weft directions and interpreted together with structural parameters. The results showed that mechanical response was governed by the combined effect of warp composition, weft architecture and structural compactness rather than by fibre substitution alone. Fabrics containing hemp in the warp did not show a uniform mechanical gain or loss across the sample set; instead, their tensile and tear behaviour depended on the associated weft design and fabric construction. Core-engineered weft yarns, particularly dual-core structures, altered the balance between tensile and tear response, indicating that yarn architecture played an important role in load distribution and deformation behaviour. Overall, the findings show that the mechanical design of hemp-containing denim fabrics should be approached through an integrated fibre–yarn–fabric perspective.