In this research, the structure of a type of bi-component composite yarns so called Marl yarn was studied.
Fibers packing density factors within the yarn cross section as well as the effect of twisting on the resultant
yarn were investigated. Samples of Marl acrylic yarns were provided using different twisting levels. Images
of the cross sections of the produced yarn were obtained using the transverse sectioning method. The
images were captured using the optical microscopy. The prepared images of the yarn cross section were
then analyzed using image processing methods. In the first stage, yarn central coordinates and radiuses
were calculated. In order to investigate the uniformity of fibers distribution and packing density within
the yarn cross section, the fiber distances from the yarn center within the small radial and polar elements
were calculated and the coefficient of variations (CV %) was determined. The maximum value of the fibers
packing density was determined. The results showed that the fibers were mostly concentrated within the
central region of the yarn; this was followed by the decrease in the fibers packing density while moving
into the yarn’s outer layers. It was also concluded that increasing the intensity of the applied twist would
result in higher fibers packing as well as the decrease in the yarn radius.