The demand for using stretchy denim apparel products is huge, thanks to the superior properties of the fabric with good elasticity and high comfort. The paper investigated the effect of the weft density parameter on the fabric structure, the elastic ratio in the fabric and the elasticity of the fabric in the vertical and horizontal directions of the bi-stretch denim fabric, which has the same ingredients of cotton core spun yarns. The higher the weft densityis, the higher the percentage of elastic yarn in the fabricis and the better the fabric structure stabilityis. However, not the higher the density, the better the elasticity, the elasticity also depends on the density correlation between warp and weft systems. This research is the scientific basis for selecting suitable textile technology parameters for finishing processing technology and design technology of garment products using stretchy denim fabric.

Keywords: Stretch denim fabric, elongation, elasticity of relaxation, fabric structures.