Fracture of common textile fibres

Abstract

Cotton, polyester, nylon, acrylic, rayon, wool, and some other fibers are used in large quantities by the textile industry for a variety of uses. Their tensile fracture results from the total deformation up to the break point. A helical assembly of fibrils with reversals and convolutions in cotton determines the stress–strain curve. Three forms of breaks are found as transverse bonding becomes weaker with moisture absorption. In wool, extension is controlled by a special microfibril-matrix structure, with fracture occurring when the rubbery matrix reaches its limiting extension. In melt-spun synthetics, the structure is uncertain, but deformation combines plastic yielding associated with crystalline regions and rubber elasticity in amorphous tie-molecules. Solution-spun fibers have a coarse structure that gives granular fractures. Weakness in the transverse direction leads to axial cracks under shear stresses and kink-band failures in axial compression. These are the commonest modes of failure in cyclic fatigue testing and in use.