Ultraviolet Protection Factor of Hemp/Filament Hybrid Yarn Knitted Fabrics

Abstract

It is generally accepted that synthetic fi bres provide high UV protection capability of textile products, while cellulose fi bres have low UV absorption capacity. However, textile materials made of synthetic fi bres are not considered to be comfortable for wear in warm weather, whereas cellulose-based textile materials are considered to be much more comfortable to wear, especially in the summer months. For this research, the idea was to produce specially blended knitted fabrics from staple/fi lament hybrid yarns in order to provide clothing materials with eff ective UV protection properties, keeping satisfactory comfort properties as well. To obtain hybrid yarns, folding technique was used. The Ultraviolet Protection Factor (UPF), as a quantitative measure of the eff ectiveness of the material to protect human skin against UV radiation, was determined for the rib knitted fabrics by in vitro test method according to the European standard. The physical properties of the knitted fabrics related to their UV protection properties: bulk density, porosity and air permeability were also determined. The hybrid yarns, from which the rib knitted fabrics were produced, having always hemp yarn as a staple component, caused the diff erences in UV protection capability of the rib knitted fabrics through the infl uence of a fi lament spun component. The hybrid yarn aggregation within knitted fabrics also infl uenced their UPF values. Even though the pure hemp knitted fabric was marked as "UPF>50" (according to European standard) due to natural pigments and lignin in hemp fi bres which act as UV absorbers, most of the hemp/fi lament hybrid yarn knitted fabrics exhibited even higher UPF. Therefore, the engineering approach proposed in this research was confi rmed as an eff ective way to design clothing materials with optimal UV protection capability and other wear comfort parameters. Keywords: ultraviolet protection factor, hemp/fi lament hybrid yarn, knitted fabric, air permeability

Hemp as a potential raw material toward a sustainable world: A review

“…Union fabric made from hemp yarn (as weft) and cotton yarn (as warp) is more rigid and shows good resistance to flammability, breaking strength, and pilling resistance [ 145 ]. Textile products manufactured from natural fibers are comfortable in warm weather though usually deficient in UV absorption, but fabrics from hybrid yarns (hemp as staple fiber; viscose, Polyamide as filament) exhibit better Ultraviolet Protection Factor (UPF) [ 146 ]. According to the Chinese Academy of Science, 95% of ultraviolet rays can be blocked by hemp fabric [ 144 ].…”