Effects of scouring with enzymes, organic solvents, and caustic soda on the properties of hydrogen peroxide bleached cotton yarn

Three different scouring methods are applied to open-end and ring spun yarn s prior to hydrogen peroxide bleaching with and without metal ions present. The scouring procedures include a penetrating treatment with aqueous sodiu m hydroxide solution, a nonswelling solvent extraction, and a fiber surface -affecting treatment with pectinase enzymes. Properties of the treated yarn s and fiber damage are studied after each process step. Conventional scouri ng with sodium hydroxide followed by peroxide bleaching causes the highest deterioration on the molecular level, but results in a high level of whiten ess. Solvent extracted yarns exhibit superior tensile strength, which is pr eserved more or less unchanged throughout any subsequent treatment. The bio scouring process with enzymes renders the yarns strikingly soft. The effect s are generally more pronounced for open-end spun yarns, suggesting that di fferences in yam structure may have an impact on the effectiveness of scour ing.