Ivo Soljačić

Impact of Artificial UV-Light on Optical and Protective Effects of Cotton After Washing with Detergent Containing Fluorescent Compounds

Abstract Bleached cotton and polyester/cotton blend fabrics were laundered at 60°C and 90°C with standard ECE detergent with addition of selected fluorescent compounds through 10 cycles. As fluorescent whitening agents for cellulosic materials are most often used in detergents, two types of these were selected – stilbene and biphenyl. UV absorber, a stilbene derivative, as a separate type of fluorescent compounds, was added on its own and in a combination with both types of fluorescent whitening agents. After each laundering cycle cotton and PES/cotton blend fabrics were exposed to artificial light for 60 and 180 minutes. Obtained optical and protective effects were monitored through whiteness degree, remission and Ultraviolet Protection Factor (UPF). Optical effects of cotton fabrics laundered in a detergent containing fluorescent whitening agents of stilbene and biphenyl type exhibit considerable sensitivity to light. It was not found that irradiation reduces the UPF meaning that even decomposition products of fluorescent compounds, created by irradiation, absorb UV radiation as well.

Adsorption and Desorption of Ionic Surfactants

Abstract Surfactants as organic compounds are widely used in the processes of textile finishing and care with regard to different variations and specific hydrophilic/hydrophobic character. Specific behaviour of these compounds is partly based on the adsorption process. In this study the adsorption and desorption of ionic surfactants have been studied upon the influence of fibre composition and surfactant ionogenity as well as variation of hydrophobic chain length and hydrophilic group in the molecule. Textile fibres were characterized through electrokinetic potential, sorption characteristics and swelling capacity expressed by moisture regain and water retention value (WRV). Different types of cationic and anionic surfactants were adsorbed on cotton, wool, polyester and polypropylene fibres at 20°C during 60 minutes. The quantity of adsorbed surfactants on textile fibres was determined by potentiometric titration. The textile fibres were centrifuged afterwards and the amount of surfactants was determined in the centrifugate, respectively. Drying followed at 60°C. The desorption of surfactants was performed at 20°C during 30 minutes. The results showed a correlation between amount of adsorbed, desorbed and residual surfactants and swelling capacity expressed through WRV.

Physical and chemical effects of washing and wet cleaning on durable press finished cotton fabrics

The influence of wet cleaning, as a promising process compared to washing, on the physical and chemical properties of functional cotton fabrics with high added value is presented. Fabric characterization before and after durable press finishing and after 10 cycles of washing and wet cleaning is made using standard methods – measuring dimensional stability, construction characteristics, crease resistance, tensile properties, swelling properties, appearance with coefficient of friction and geometrical roughness, surface characterization by scanning electron microscopy and electrokinetic potential. It can be seen that wet cleaning, which has been used in practice, together with adequate pretreatment, as a substitute for dry cleaning, can also be successfully implemented as a process to substitute washing, particularly when high-value-added articles are concerned.

The Impact of Fluorescent Compounds on the Change in Shade of Pastel Colored PES/Cotton Fabrics

Abstract Functionalization of textiles in the finishing and care processes is an outstanding topic today. Ultraviolet (UV) protective properties of textiles can be improved by the implementation of fluorescent compounds in the finishing and laundering processes. The investigation described is focused on the addition of a fluorescent whitening agent (FWA) and an UV absorber (UVA) during frequent laundering of bleached and pastel colored polyester/cotton fabrics in the reference ECE detergent at 40°C. The effect of the UVA containing detergent includes improved whiteness of bleached textiles and excellent UV protection properties during multiple cycles. The bleaching performance of the FWA is similar in offering good UV protection. In the case of the pastel colored fabrics after the launderings, UV protection is excellent too, but the negative impact of the fluorescent compounds on the changes in shade is evident.

Determination of Iron and Copper in Textile Materials by Anodic Stripping Voltametry

Heavy metals at low concentrations can have a damaging effect in chemical and optical bleaching of textile materials. The application of anodic stripping voltametry for determining copper and iron in textile materials is described. The preparation of the samples of cotton, wool, polyester, polyamide, and polyacrylics, and procedures for determining Cu and Fe in these materials are reported.

Effect of Condensation Temperature on Formaldehyde Release from Durable Press Fabrics

We investigated formaldehyde release from cotton and polyester/cotton materials treated with DMEU and DMDHEU resins at different condensation temperatures. In the samples treated with DMEU, the amount of free formaldehyde was greater at lower condensation temperatures. Samples treated with DMDHEU gave similar results when the AATCC method for determining formaldehyde was used, but when the MITI method was used, the condensation temperature-formaldehyde curves showed a minimum at about 140°C. The release of formaldehyde is a slow process, because both methods gave similar curves when longer extraction times were used. Changing the extraction temperature gave a quantitative difference.