Salt-free dyeing of cotton fabric <i>via</i> graft polymerization with chitosan using dimethyl itaconate as a renewable cross-linker

The dyeing of the cotton fabric with reactive dyes is the most commonly used process in textile industry. However, the extensive use of inorganic salts poses significant environment and health concerns. To address this, the recent studies has focused on modifying cotton fabric using bio-degradable resources. In this work, chitosan and dimethyl itaconate were grafted on cotton fabric through graft polymerization reaction using ammonium per sulphate as initiator. The modified cotton was characterized through FTIR, SEM and EDS techniques. Under the condition of no organic salt, the modified and non-modified cotton were dyed with C.I. reactive blue-4, C.I. reactive orange-16, and C.I. reactive black-5 under varying dye concentration, time and temperature. The colour strength properties, analysed through <i>K</i>/<i>S</i> values, revealed that the modified cotton showed the better <i>K</i>/<i>S</i> value as compared to non-modified cotton. Furthermore, a comparative analysis of colour fastness to washing and rubbing indicated that the modification did not adversely affect the colour depth.