The Mechanism of Pilling

Abstract

Studies of the mechanism of pilling have demonstrated that pilling propensity is determined by the rates of fuzz formation, entanglement, and pill wearoff. Motion pictures of fabrics subjected to an abrading action showed that the abradant acted on exposed fiber sections to pull loops which then opened to form fuzz. A pill formed quickly when the fuzz density reached a critical level. The fibers were then twisted and entangled, gradually involving nearby fibers. As the abrading action continued, pills wore away. Techniques were developed which permitted independent quantitative study of each of these three phenomena. The physical properties of several textile fibers were correlated with their behavior in these tests. Interfiber friction and bending stiffness were important factors in fuzz formation. Entanglement tendency was correlated with denier, cross-sectional shape, and bending stiffness. Pill wearoff was determined by abrasion resistance and tenacity. The general applicability of this mechanism has been demonstrated with modified polyester fibers. The reduced pitting tendency of ribbon staple fibers was attributed to a directional bending which reduced their entanglement tendency. Heat-setting increased bending stiffness, which reduced pilling by lowering fuzzing tendency. The most pronounced effect on pilling tendency of polyester fibers was obtained by changes in abrasion resistance, which affected the rate of pill wearoff.