Two fundamental concepts are defined, the effective crimp diameter and the effective wave number. The corresponding figures for these concepts are calculated from the measurements of the width values of the plane projection of a rotating fiber and from the measurements of the crimp ratio. These figures are obtained for a fiber under a certain load, and take into account the spatial nature and the statistical aspect of crimp. An effective curvature is determined as well. Results are obtained for 90's Merino and 52's Scotch-Blackface wool fibers. It is shown that the higher quality wool fibers are associated with lower effective crimp diameters and higher effective wave numbers.

The main parameter used to describe the geometry of the crimp of a fiber is the crimp diameter. This corresponds to an average amplitude of the fiber in space while the fiber is kept in a static position of stress. In order to measure the crimp diameter, it is necessary to measure the coordinates of a sufficient numher of points on the fibers. From these measurements, a "fiber axis" can be defined as the straight line for which the sum of squares. S. of the distances of the fiber points from this line is minimal. The crimp diameter is then defined as D=2√S N, where N is the number of points measured along the fiber. The calculation of S according to this definition involves the solution of third-order equations. Therefore a simplified equation is suggested. It was found that this equation can. for all practical purposes, serve as a satisfactory approximation for the results obtained when S is calculated according to the definition . i.e., from the fiber axis. In order to measure the crimp diameter, a special apparatus had to be built. A series of limitations of the rotatory crimp apparatus led to the modification of the measuring method and to the, development of the method of two perpendicular planes. This method was applied to various types of fiber, such as cotton and fine wools.

In this work the uncrimping force and energy are used to characterize the crimp of wool fibers. These parameters are measured through the load-extension curves of single wool fibers.It seemed necessary to investigate the stability of the uncrimping energy and force. This stability is referred to as crimp recovery. The dependence of crimp recovery on recovery times as well as on the amount of extension was studied.It was found that for immediate recovery the crimp decreases, and that this decrease varies with the percent of final extension of the fibers. When the fibers are kept in a relaxed state after the final extension for various times, it is found that the crimp recovery is almost complete after 24 hr of relaxation; with smaller times of relaxation the crimp recovery increases with time, while the extent of the recovery depends on the amount of final percent of extension—the higher the extension the lower the recovery.---------

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 diffference 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.

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