Light transmission of weft-knitted fabrics for seamless garments

Abstract

Knitted seamless sportswear offers ‘body-mapped’ comfort and support, but there is a risk of exposing the human body in public due to the low density and large fabric deformation of the sportswear when wearing it. This paper presents an experimental study on the light transmission behavior of different weft-knitted fabrics for seamless sportswear in different stretching modes to understand the light transmission principle. Three plain knit fabrics for seamless sportswear made from three yarn combinations were compared: a polyamide 6 (PA6) yarn, a combination of spandex and PA6 yarns, and a combination of spandex, PA6, and polyethylene terephthalate (PET) yarns. Three modes of stretching were performed on the three fabrics, namely uniaxially, uniaxially with transverse restraint, and biaxially, to simulate wear deformation. The stretched fabrics are analyzed in terms of cover factor, thickness, and light transmission. The results showed that light transmission increases with increasing tensile strain. The presence of restraint further increases the light transmission, and biaxially stretched fabrics have the greatest light transmission. The thinnest PA6 fabric has the lowest cover factor and the highest light transmission, while plating a spandex/PA6 covered yarn on a PA6 yarn shrinks and tightens the fabric, and therefore reduces the light transmission. Adding an additional PET yarn reduces shrinkage and thickness, increasing light transmission. Light passing through the fibers and loop meshes of a fabric accounts for total light transmission. Plating a coarser elastomeric yarn into weft-knitted fabrics for seamless sportswear is an effective way to increase the spaces in yarns and shrink the loop meshes, thereby reducing the light transmission.