Change in physical properties of cotton fabric caused by natural indigo dyeing

Abstract

Physical properties of cotton fabric, which was dyed with natural indigo reduced by fermentation, were studied. Cotton fabric showed maximum value of tensile energy, WT, tensile strength and abrasion resistance at dye uptake of 44 mg/g. Mean of friction coefficient, MIU, showed a maximum at dye uptake of 11.6 mg/g and then decreased with an increase in dye uptake. XRD reflection proved that cotton fiber was dyed with natural indigo in aggregate state. Natural indigo dyeing gave cotton fabric smaller air permeability, smaller heat conductivity and smaller initial maximum value of heat flux than synthetic indigo dyeing with an increase in dyeing times. The cotton fabric dyed with natural indigo exhibited larger mechanical properties except for abrasion resistance than those with synthetic indigo reduced by hydrosulfite at dye uptake of about 45 mg/g. It was suggested that natural indigo dyeing changed the structure of cotton fiber in association with high-order structure of fiber.