Properties of Apparel Wools

Abstract

A description is given of the measurement of the tensile force-extension curves of fiber as semblies with no net twist—i.e., top and roving produced on the French worsted system. Typical force-extension curves are presented, and the effects of testing conditions on various parameters of these curves have been determined. These force-extension curves are a measure of the forces required to cause the fibers to slip over one another; they depend on such factors as fiber length, fiber diameter, fiber modulus of elasticity, interfiber coefficient of friction, and fiber crimp, and on density of fiber packing in the assembly, fiber parallelism, and weight per unit length of the assembly. The relationships between the above factors and parameters of the force-extension curve are discussed in the light of the use of these measurements to investigate processes which affect any of these factors or to characterize different fiber types.The variability of parameters of the force-extension curve is discussed. Part of the variability may be ascribed to slight differences in the performance of the machine units producing the assemblies.