Expanding the Utility of the Agricultural Research Service (ARS) process bleaching

Abstract

The Agricultural Research Service of the U.S. Department of Agriculture conducts research on agricultural products and co-products where wool is a co-product of the American lamb industry. The ARS process, an alternative to conventional peroxide for bleaching and chlorination for shrinkproofing wool, was applied to bleach and control the dimensions of wool, wool/cotton, cotton, and viscose rayon fabrics. Conventional processes for bleaching and shrinkage control have limited economy due to high temperatures and long exposures, and their ecological acceptance is marginal. The ARS process is chemo-enzymatic with bleaching followed by biopolishing with shrinkproofing, both steps being applied at near-room-temperature conditions for 30—40 minutes to reach high levels of whiteness, softness, and dimensional stability. The novelty of the process involves the in situ formation of a hyper-peroxide bleach to achieve high whiteness with subsequent enzyme processing from a fresh bath to selectively treat only the surface scales of wool without damage to the inner cortex of the fiber. The Whiteness Index (WI) of wool and wool/cotton improved 63%—72% after bleaching alone and another ~2% increase after enzyme treatment; area shrinkage was less than 2%. The WI of cotton print cloth improved 60.5% by ARS bleaching compared to 64% by conventional bleaching. The process limited shrinkage of cotton knit to 4% and to less than 2% for cotton and viscose woven fabrics. The mechanical properties of all treated fabrics were retained. In a separate study, the process was applied at high concentration to convert wool jersey into parchmentized jersey with permanent stiffness and 45.5% increase in sheerness, as determined digital image analysis. ARS novel bleaching is a sustainable, facile, effective process for low-temperature bleaching with low energy consumption and low environmental impact. Wool jersey with sheerness, stiffness, and strength retention can be fabricated by treatment with highly concentrated ARS hyper-peroxide bleach.