Crimp frequency

Current evidence suggests that crimp frequency in wool is determined by the relative proportion of the three types of cortical cells, their location in the fiber cortex, and the protein composition of the matrix of the orthocortical cells [84]. 

ASTM D 3937 provides a method for determining the crimp frequency of synthetic staple fibers, but the between-laboratory variation is known to be great. It is, however, suitable for in-house QC operations. 

Crimp frequency. The number of full waves or crimps in a length of fiber divided by the straightened length. 

Crimp frequency is defined in ASTM D 3937 as "in man-made staple fibers, the number of crimps or waves per unit length of extended or straightened fiber." Compare this with the Textile Institute definition given above. 

ASTM D 3937-90 provides a method for determining the crimp frequency of manmade staple fiber irrespective of how the crimp was inserted or developed. Equivalent ISO and BS methods are not available. 

To illustrate this, a figure shows stylized crimped fibers with various degrees of crimp frequency, ranging from 4 to 23. 

ASTM D 3937 94 Test method for crimp frequency of man-made staple fibers. 

Dissymmetric orientation can also be performed by oblique spinning (20—70°) with respect to the sjanneret, drawing by 600% in water at about 50 °C, and heat-setting in a relaxed state at 180 °C. A crimp frequency of more than 20 per cm has been reported ... 

Crimp frequency The crimp level, or number of crimps per inch in yarn or tow. 

New instrumentation for measuring fiber diameter (13,14) has meant that data on the range of diameters present (CVd) and fiber curvature (related to crimp frequency) are now available. The impact of these is fairly well estabhshed (15). 

Crimp frequency (KD) no. of crimps/10 cm Internal FV test Variable ... 

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