Characterization of nano-sized TiO₂ suspensions for functional modification of polyester fabric

Three industrially-prepared (via the sulphate synthesis process) and commercially-available nanoTiO₂ colloidal suspensions were coated on polyester fabric using the conventional pad-dry-cure procedure, in order to enhance fabric functionalities by imparting self-cleaning and UV-protection ability. Various characterization techniques, i.e. transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and UV/Vis spectroscopy of the suspensions revealed the presence of anatase TiO₂ spherical-shaped nanoparticles of different crystallite sizes, as well as its prominent absorption capacity within the UV region. Scanning electron microscopy (SEM) was adopted to analyse the morphological structure of nanoTiO₂-modified PES fabrics. Furthermore, the photocatalytic activity was investigated through the discolourations of red wine and red beet stains under two types of light sources, i.e. direct day light and artificial UV light, by means of a spectrophotometry. The UV-protective properties were also evaluated by calculating the ultraviolet protective factors of individual coated fabric. The obtained results show acceptable blocking properties against UV-rays, as well as the adequate self-cleaning abilities of TiO₂-modified PES fabrics as governed by the types and concentrations of applied TiO₂ suspension.