Investigation of the Optimum Pretreatment Conditions for the Knitted Fabric Derived from PLA/Cotton Blend

Abstract

The pretreatment processes prior to dyeing which were the scouring and bleaching, for the knitted fabric of PLA/cotton blend were studied comparing with the 100% cotton and PLA fabrics. These two pretreatment processes were studied in a sequence (scouring followed by H 2 O 2 bleaching) and altogether in the one-bath process. The scouring process of the blended fabric was compared when the different scouring agents were employed (NaOH, Na 2 CO 3 and pectinase enzyme). The two-bath and one-bath scouring/bleaching processes had a signified effect on the strength of the fabrics because the pretreatment processes typically used for cotton are in the alkaline condition which can deteriorate the PLA fiber. Therefore, the pretreatment conditions for the PLA/cotton blended fabric needed to be optimized to avoid fiber damage. From the research, it was observed that the pretreatments for the blended fabric, which was to enter the pale-shade dyeing, were scoured using 10%owf pectinase (60C, 60 min) as it enhanced a satisfactory water absorbency to the fabric without causing any adverse effect on the fabric strength. For deep-shade dyeing, the blended fabric should undergo the one-bath scouring/bleaching with 7%owf H 2 O 2 (100C, 60 min) which yielded a water absorbency and whiteness on the fabric to a standard level and the resulting fabric strength was highest and this one-bath pretreament was the time-saving process.