Influence of knitted fabric construction on the ultraviolet protection factor of greige and bleached cotton fabrics

The alarming increase of incidence of skin cancer has hastened development of ultraviolet (UV) protective clothing and research on UV protection of apparel. Although various fabric parameters that affect ultraviolet radiation (UVR) transmission were studied by researches, most of them focused on woven fabrics and chemical approach in enhancing UV protection. There were few studies concerning knitted fabrics, in particular the influence of fabric constructions on ultraviolet protection factor (UPF) and structural properties. The magnitude of transmission and scattering of UVR through a fabric is decided by fabric construction or knit structure, which is classified by geometrical arrangement of yarns and fibers of the fabric. This paper aimed at studying the influence of different knit structures upon the UPF with the three main knit stitches incorporated in the knitted fabric constructions, namely the knit, tuck and miss stitches. The UPF and structural characteristics, including thickness, weight, stitch density and porosity of greige and bleached knitted fabrics with different knit structures, are compared by adopting factorial analysis of variance. The results show that fabrics with miss stitches possess a higher UPF than fabrics with tuck stitches. The double-knitted fabrics have better UV protection than the single-knitted fabrics overall, but bleaching has different impacts on the UPF of single- and double-knitted fabrics. The study reveals that fabric thickness or weight cannot be used solely in explaining the UV protective performance of knitted fabrics. However, fabric porosity can be a good indicator for UV protection when comparing fabrics with similar fabric weight and thickness but different structures or fiber contents.