A Modification of the Method for Defining and Measuring Crimp of Textile Fibers1

Abstract

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.

The Crimp of Cotton Fibers

“…The crimp meter, which serves to measure the static crimp parameters, was described in a previous paper [6]. The measuring system includes a dial reader for the extension values and a torsion balance.…”

“…lii order to minimize handling they were glued cm celluloid frames according to the technique described by Shiloh et ;tl. [6]. 'I'he inner length of these frames was 15 mm, thus the length of the fibers tested cm both types of apparatus was approximately 15 mm.…”

“…'rs in terms of changes of length and not of shape. Definitions of crimp properties, based on the geometrical aspect of crimp, have been developed at this Institute [1,6]. Th~se geometrical properties, measured under various loads, are considered to be the static crimp parameters.…”

“…It has already been suggested [6,2] to use the static and the dynamic parameters together as a method for measuring the crimp of textile fibers.…”

The Crimp of Wool Fibers

“…Attempts to define and measure crimp have been made hy various authors EI-6, 8,10]. However, comparatively little has been reported on the determination of crimp of wool fibers from the load-extension curve over the decrimping range because forces involved in such measurements are extremely small.…”