The International Istanbul Textile Congress 2013 May 30th to June 1th 2013, Istanbul, Turkey 1 EFFECT OF CORONA TREATMENT ON GRAY AND BLEACHED COTTON FABRICS V. SHAKERI 1 , P. VALIPOUR 2 , E.EKRAMI 3 , A.R. SHAKERI 1 1 Department of Textile Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran 2 Department of Textile Engineering, Qaemshahr Bragvnnch, Islamic Azad University, Qaemshahr, Iran 3 Department of Textile Engineering, Amirkabir University of Technology, Tehran, Iran Vahid_shakeri@ymail.com Abstract: In the present study, the effect of corona treatment on cotton fabrics was investigated. Gray and bleached samples were treated by corona discharge at different levels of passage and power. Subsequently, the treated samples were characterized by Attenuated Total Reflection Fourier Transform spectroscopy (FTIR-ATR) as well as whiteness and yellowness indexes. Based on the obtained results, the power and number of passages in the corona process have significant effects on the amount of carboxyl and carbonyl groups of the fabric surface and whiteness and yellowness of samples. The washing step after corona treatment was also found to have positive effects on whitness of fabrics. Keywords: corona discharge, cotton fabrics, bleaching process, whiteness, yellowness. 1. Introduction Cotton with excellent properties such as high moisture absorbency, wear comfort and good dyeability, occupies the second place next to polyester in the world’s production of textile fibers [1]. The impurities in cotton fibers range from 4% to10% [2, 3]. In the preparation technology of cellulosic textile fibers, the bleaching process is not only concerned with brightening of the fibres, removing the natural coloring matter, e.g. fats, waxes, pectins, proteins and pigments, but it is directly related to the success of subsequent wet processing operations such as dyeing, printing and finishing. The whitening of textiles is achieved with different oxidizing or reducing agents, capable of destroying the natural coloring matter present in the fibers. One of the most common bleaching methods is hot hydrogen peroxide bleaching under alkaline conditions. The whiteness level aimed in bleaching depends on the end use of the fabrics. When higher whiteness is needed it is necessary to perform a repeated oxidizing treatment. The bleaching chemicals normally are dosed in excess to the fibers, which necessitates repeated washing to remove the residual, harmful to the next processing operations, oxidants. This process is energy intensive and consumes high chemicals, water, and time, discharging environmentally hazardous waste liquors. Corona discharge is a non-polluting technique based on the production of plasma at ambient pressure. The products of a corona discharge are available for reaction with any introduced substrates. Fabric can be corona-treated by passing it between electrodes and an electric discharge (> 10 000 V, 20 –40 kHz) made at ambient temperature and pressure. Conventional methods for the preparation, dyeing and printing of textile materials have a great environmental impact because of the processes involved. The textile industry is therefore obliged to adapt in order to comply with ecological legislation. Corona technology allows the use of a modified dyeing process (i.e. chemicals are no longer required and lower processing temperatures can be used) which reduces ecological and economical cost factors for the textile industry [4-6]. In the present work corona discharge pre/after-treatment was applied to the process of cotton fabric bleaching by hydrogen peroxide and subsequently the whiteness of the treated samples was assessed. The bleaching results of the corona-treated materials under different conditions were compared with those of untreated bleached cotton 2. Materials and methods: 2.1. Materials: In order to investigate the effect of corona discharge and bleaching treatment on fabric samples, the gray and bleached single jersey fabrics were knitted 100 % cotton yarns (30 Ne), which the fabric weight was 60 g/m 2 . All chemicals used were analytical grade. 2.2. Bleaching treatment: The fabrics were bleached using sodium hydroxide (2.5 % NaOH) and 0.4% of hydrogen peroxide (6 % H2O2) for 60 minutes at temperature 100 o C and with L.R of 1:30.