A pilling mechanism for cellulosic knit fabrics – effects of wet processing

Abstract

The length of fuzz and pill formed on regenerated cellulosic knitt fabrics after washing and drying (WD) was determined by electrical resistivity measurements perpendicular to the plane of fabric. The fuzz length of Lyocell Knitted Fabric 1 after 25 times WD was 1.05 mm and was the longest among the three different lyocell fabrics. The visual pilling extent of the Lyocell 1 was also higher compared to the other lyocell fabrics. Fiber–fiber friction was measured as counts of twist to open the yarn until it starts to slip in dry (T rdry) and in wet (T rwet) conditions. The T rdry of Lyocell 1 was 30.5 counts and comparatively low. However, the T rwet of Lyocell 1 was remarkably high. The high T rwet of Lyocell 1 was related to a higher water retention value (0.943 g/g) which was centrifugally measured. The contraction force of the yarn bundle in water was additionally determined. The results of parameters indicating the fiber properties in dry and wet conditions suggested a mechanism of pill formation. The fuzz formation was promoted by lower fiber–fiber friction, which allows the ends of fibers to come out from the yarn during mechanical abrasion. As the fibers get softer and the fiber–fiber friction gets higher due to the swelling in water, the fibers easily tangle to develop pills.