Cross‐sectional shapes of the yarn in cotton gray woven fabric

Abstract

This experimental work looks into the geometry of the yarn cross‐section at the weaving and relaxed stages using microscopic and digital image processing techniques. A total of 54 plain‐weave cotton fabric samples (different in the yarn twist and the fabric density) were produced and the cross‐sectional shapes of the wefts at the early stage of weaving (in which the wefts were also under tension by full‐width temples) and at the relaxed state were compared with the ideal circular shape. The measurements of the samples showed that the cross‐sectional shapes of the yarns at the early stage of weaving are circular, elliptical or a combination of two circles or an asymmetric elliptical. Moreover, the effect of the fabric tightness on the yarn cross‐sectional shape and dimension was negligible. The measurements of the cross‐sectional dimensions of the relaxed fabric (released from weaving tension) showed an increase in the area occupied by the yarn inside the fabric and did not follow the Peirce standard model. The measurement and the comparison showed that the cross‐sections of the yarns inside the woven fabric could be categorized into five different shapes, namely; circular (C), elliptical (E), sharp symmetrical amygdaloidal (SSA), asymmetrical amygdaloidal (AA) and sharp asymmetrical amygdaloidal (SAA), but the number of each group depends upon the yarn properties and the fabric structures. The fabrics with the highest density and the highest twisted yarns had a circular cross‐sectional shape, whereas the fabrics with the lowest fabric density and the lowest twisted yarns had the most flattened yarn cross‐sections in the form of sharp symmetrical or asymmetrical amygdaloidal shapes.