The Crimp of Cotton Fibers

An investigation of the crimp properties of cotton fibers is presented. Two independent groups of parameters are used: one describing the geometry of the fiber and the other the dynamic behavior of its crimp. The static parameters—the crimp diameter and the crimp ratio—are measured on a crimp meter. The dependence of these parameters on the applied load is determined, and some functional relationships are suggested. The dynamic parameters used are the uncrimping energy and the uncrimping force. Both are determined from the load-elongation curves, recorded on the Instron tester. The coefficients of immediate and retarded recovery of crimp of fibers subjected to tensile deformation are determined. Two varieties of cotton are tested: Deltapine 15 and Acala 1517. A significant diff ference between the mean static parameters of these varieties is found. The more crimped appearance of the Deltapine fibers is confirmed by the higher values of these parameters. Furthermore, the force necessary to draw out these fibers from the lot is found to be higher than for the Acala fibers. The values of the uncrimping energies of the Deltapine fibers are also found to be significantly higher than those of the Acala. The values of the recovery coefficients show that about 50% of the uncrimping energy of the Deltapine fibers is recovered immediately after stretching. The corresponding recovery of the Acala fibers is about 25%. After 24 hr of relaxation, the fibers of both varieties show a recovery of 55%. The uncrimping force and its recovery coefficient are found td be less sensitive parameters for characterizing these cotton varieties.