Activated Peroxide for Enzymatic Control of Wool Shrinkage Part II: Wool and Other Fiber-type Fabrics

Abstract

In Part I we investigated the mechanism for bleaching wool with activated peroxide in the pretreatment step of the chemoenzymatic ARS process for whitening, biopolishing, and shrinkage prevention of wool. Here in Part II we report on applying the process to wool woven and knit fabrics of various constructions and fabric weights and to woven fabrics of other fiber compositions. The contribution of relaxation shrinkage to overall shrinkage that includes felting shrinkage is pronounced in wool fabrics, especially knits. The ARS process is specific for controlling felting shrinkage to provide dimensional stability in machine washing and drying. When applied to acetate, cotton, nylon, polyester, viscose, 62% wool/38% cotton, and a wool/Nomex blend the process was most effective for controlling the shrinkage of acetate, cotton, nylon, viscose, and wool/cotton blend. We treated wool, cotton, and viscose at pH 11.5, 30°C for 30 minutes with individual components used in ARS pretreatment: dicyandiamide (DD), gluconic acid (GA), alkali (NaOH), and hydrogen peroxide (H2O2), and subsequently applied the enzyme treatment. We found that NaOH imparted a mercerizing effect to cotton and viscose and shrinkage was limited to less than 1%. Only the combination of DD/GA/NaOH/H2O2 imparted highest whiteness to wool, cotton, and viscose. When pretreatment utilizing activated DD peroxide was followed by enzyme applied at pH 8–9, 45°C for 40 minutes, the wool fabrics became dimensionally stable and biopolished for itch-free comfort.