Effects of variation in wool fiber curvature and yarn hairiness on sensorial assessment of knitted fabrics

Abstract

Previous investigations have shown that prickle discomfort sensations of wool fabrics are primarily determined by the mean fiber diameter of the wool. It is also known that differences in wool fiber curvature (crimp) affect softness of handle of greasy wool and of wool textiles. In a replicated experiment, we investigated if wearers could detect the effect of using 17 mm superfine wool of low (74 /mm) or high (114 /mm) fiber curvature, and when the wools were blended with 17 mm cashmere (fiber curvature 49 /mm) in differing proportions, on four comfort sensations. Eight single jersey knitted fabrics were assessed under a controlled protocol using forearm sleeves made of the test fabric and a control fabric. Data (37 sensorial assessments of high curvature wool fabrics; 38 sensorial assessments of low curvature wool fabrics) were analyzed using linear mixed model analysis (restricted maximum likelihood), which included fixed effects for wool type and blend ratio and a random effect for participant. The use of a control sleeve fabric reduced variance due to participant effects by providing an anchor for each sensation over time. Wool fiber curvature affected participant assessment of breathability, comfort, feel after exercise (damp/dry) and skin feel (prickly/soft), with preferred values associated with high curvature (crimp) superfine wool. Increasing the proportion of cashmere in fabrics increased skin feel (better assessed softness). Skin feel was strongly associated with the evaluation of the fabrics by the Wool ComfortMeter and with increasing hairiness of yarns.

Fabric handle properties of superfine wool fabrics with different fibre curvature, cashmere content and knitting tightness

“…This result may reflect the lack of finishing treatment applied or perhaps yarn twist, which was higher than frequently used for knitwear, but the same twist was used for all yarns. However, increasing yarn hairiness (T p , S 3 ; Table 5) was positively associated with smoother assessment, a finding similar to responses from wearers of fabric composed of the same yarns (McGregor, Doughty, et al, 2015).…”

“…It is surprising that there were no effects on fabric clean/hairy handle as the yarns composed of lower curvature superfine wool have been shown to have higher hairiness attributes compared with yarn of the higher curvature wool (McGregor & Postle, 2007;Wang et al, 2006) and that these differences in yarn hairiness have been shown to be associated with other fabric properties (McGregor & Postle, 2007) and wearer assessments of fabrics composed of these yarns (McGregor, Doughty, et al, 2015). Previous research has shown a negative linear response to fabric density, where increasing fabric density was associated with reduced hairiness , and this result was also found in the present work at TF's 15.5 and 17.0 (Table 5).…”

“…Variation in fibre curvature of superfine wool has been shown to affect the wearer assessment of fabrics knitted with these yarns and 2 B.A. McGregor and M. Naebe also the instrumental assessment of fabric comfort properties (McGregor & Naebe, 2013;McGregor, Doughty, et al, 2015). In another investigation, the manipulation of raw wool staple crimp frequency (curvature) provided no discernible effects upon laboratory assessments of fabric handle assessment within a very narrow range of fibre curvature investigated (117 compared with 128°/mm; Tester, McGregor, & Staynes, 2015).…”

“…Comfort involves physical interaction between the human body, the fabric and the external environment, while handle is the reaction to the mechanical interactions between human skin and the fabric, where both the fabric surface and the material bulk are being spontaneously evaluated by external body movement. In recent studies, it was shown that prickle discomfort is driven by the mean fibre diameter (MFD) of the wool and the length of fibres protruding from the surface of the fabric or yarn (McGregor, Doughty, Thompson, Naebe, & Tester, 2015;Naebe, McGregor, Swan, & Tester, 2015).…”

Structure and Properties of Oxidized Chitosan Grafted Cashmere Fiber by Amide Covalent Modification

“…Therefore, the surface of CF fiber is treated to overcome these limitations via transformation of the fiber surface structure, altering the chemical components, which generally include well-designed constituents to the surface or interior of CF, or grafting them on the macromolecule of the CFs. For example, the performance of CFs can be improved by (i) plasma and ultrasonic treatment, changing the apparent morphology and internal structure, or (ii) using acid, alkali, crosslinking agent, and other chemical reagents to change the chemical the ingredients commonly used for the modification methods [ 6 , 7 , 8 , 9 , 10 ].…”