Document Type : Original Article
Department of Textile Engineering, Isfahan University of Technology, Isfahan, Iran.
Recently, there has been an increasing interest towards the finishing of textiles (fibers, yarns, fabrics and nonwovens) using eco-friendly technology, which can achieve a wide range of functional properties and environmental benefits. This study is related to a modern eco-friendly bleaching technology that relies on Ultraviolet/O3 radiation of poly(lactic acid) fabric through simple technique. The effects of Ultraviolet/O3 radiation along with the pretreatments with distilled water, hydrogen peroxide, and hydrogen peroxide/sodium silicate solutions on the bleaching of the poly(lactic acid) fabrics were examined using UV-Visible and reflectance spectral method and the results were compared with that of virgin untreated samples. Ultraviolet/O3 bleaching routes were screened to obtain desired whiteness index (WI), tint factor (Tw), lightness/darkness (L*), redness/greenness (a*), yellowness/ blueness (b*), chroma (c*) and hue (h˚) of the bleached poly(lactic acid) fabrics. The optimal properties of the bleached poly(lactic acid) knitted fabric could be obtained at Ultraviolet/O3 irradiation for 80 min on the fabrics which pre-impregnated in a hydrogen peroxide solution with a wet pick up of 70 %, pressure of 1.1 bar and speed of 2 m/min. (Ultraviolet/O3/H2O2 bleaching system). The Ultraviolet/O3/H2O2 bleached fabric showed the best colorimetric properties (WI: 87.7, : -0.1, L*:94.227, a*:-0.106, b*:0.294, c*:0.2512, h˚: 98.6551). Moreover, the reflectance of this sample has increased significantly in the range of 400-450 nm which leads to a glossy withe shade on the fibers. The SEM images presented that after Ultraviolet/O3/H2O2 bleaching process, some fractures with nano scale size (about 130 nm) are formed on the poly(lactic acid) fabric surface. The ATR-IR spectrum of Ultraviolet/O3/H2O2 bleached poly(lactic acid) fibers displays more intense C–C–O absorption bands (1161 cm-1).