Studies on Incorporating Infrared Reflecting Minerals into Viscose Fibres

A mixture of minerals consisting of calcite, dolomite, talc and quartz, known to have infrared (IR) reflecting properties, was mechanically treated and dispersed in aqueous medium and incorporated in viscose solution to be physically entrapped into the fibre structure. The process of incorporation of the mineral mixture in viscose dope involved steps of slurry making by suspending and grinding the particles in aqueous medium followed by mixing the slurry with the viscose dope, ready for spinning. The slurry preparation and grinding were carried out under different mechanical conditions, such as ball milling and ultrasonication. The evaluation of particle size of slurry was carried out under two pH conditions, first at the inherent pH (neutral pH 7) and at high pH (alkaline pH 13) equivalent to the pH of viscose dope. Furthermore, for stable slurry making, different surfactants were used. The phosphate ether-based anionic surfactant was found to effectively stabilize the dispersion better under the pH conditions used. The effect of stable slurry on good spinning was validated through an inline pressure gauge during viscose fibre spinning. To assess the IR reflecting property of viscose fibre, a direct visual evaluation was done through an IR camera, which indicated a significant increase of ~2°C surface temperature of the IR-Viscose Staple Fibre (VSF) in comparison with control VSF.