Influence of atmospheric pressure air plasma on the surface properties of raw knitted cotton fabric

Raw Cotton or Grey Cotton contains impurities such as natural oil, waxes, pectin and coloring matter, etc. Due to presence of these impurities raw cotton/grey cotton fabric is hydrophobic in nature and is not suitable for dyeing or printing. Conventionally various types of chemicals and reagents are required to remove these impurities. A typical pre-treatment of 1 Kg of Cotton fabric requires about 350 liters of water for pre-treatment. Plasma treatment can be used as alternative dry method for removal of these impurities from raw/grey cotton fabric and generate hydrophilic groups on its surface. This in-turn makes the fabric suitable for dyeing. In the present work, we have used a high frequency dielectric barrier discharge in air at atmospheric pressure for the surface modification of grey knitted cotton fabric. The surface properties of plasma treated cotton fabric are studied by using Video-Contact Angle Goniometer (VCA), ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared Spectroscope and FE-SEM (Field Emission Scanning Electron Microscope). The water contact angle of cotton fabric reduces from 135 to 0 (complete wetting) for a plasma exposure of 5 minutes. The water absorption time of untreated fabric is around 2400 seconds to 0.14 seconds. The FTIR analysis on the surface of plasma treated cotton demonstrates removal of wax and pectin as well as formation of hydrophilic groups such as C=O. The SEM analysis reveals the morphological changes induced by plasma treatment. (author)