Studies on cotton–acrylic bulked yarns and fabrics. Part I: Yarn characteristics

The effect of variables, namely yarn fineness, shrinkable acrylic proportion and twist level, on various properties of cotton–acrylic blended bulked yarns has been studied by relaxing shrinkable component of the yarns using boiling water treatment. A three-variable factorial design technique proposed by Box and Behnken was used to investigate the combined interaction effect of the above variables on the properties of these yarns. The design variables were optimized for all the yarn properties by using the response surface equations. The shrinkage percentage of yarn was found to be higher in the case of coarser yarn, yarn with higher proportion of acrylic fibre and higher twist level. During bulking treatment as the yarns shrink, the effective number of twist per unit length also increases significantly. It is observed that the specific volume of the yarn increases with an increase in the acrylic proportion and decreases with an increase in the twist factor. The breaking extension increases significantly after bulking with a slight increase in tenacity. The flexural rigidity and initial modulus of yarn considerably decrease on bulking. The vertical wicking heights for all the bulked yarns were found to be higher than comparable 100% cotton yarn.