Water Wetting and Retention of Cotton Assemblies as Affected by Alkaline and Bleaching Treatments

This paper reports quantitative measurements of improved water wettability and retention of scoured and bleached cotton fabrics. The water wetting contact angles (CAs) of raw cotton fibers and grey plain weave and satin weave cotton fabrics are 95.3° (±19.4°), 93.9° (±3.3°), and 93.2° (±4.7°), respectively. Improved water wet ting properties with alkaline scouring (3% NaOH ) depend on the forms of the cotton assemblies that are scoured and the duration of the scouring. Water wetting CAs of single fibers (CA = 0.3° ± 0.5 ° ) improve to a much greater extent when scoured (2 hour) in loose fiber form than in the yarn (40.8° ± 7.3°) or fabric (41.3° ± 5.4° ) form. Water wetting contact angles of single fibers taken from the scoured plain weave fabrics are identical to those of fabrics and yarns scoured under the same conditions. Scouring improves water wettability and water retention even when the pore volume in the fabric is reduced. Bleaching, on the other hand, improves surface wettability and water retention without affecting the fabric pore structure. The water retention properties of these scoured and bleached cotton fabrics are directly related to their wetting properties in water, or inversely related to their water wetting CAs. These quantitative methods are highly sensitive to differentiating the effectiveness of scouring and bleaching processes on cotton assemblies.