Salt-free Reactive Dyeing of Amino-acid Modified Jute

Investigation on the effects of chemical modification of jute using three different amino acids (alanine, glycene and 4-amino butyric acid) on dyeability for application of different reactive dyes in exhaustion method with or without salt has been carried out. 8% glycene treatment on 3% H2O2 bleached jute fabric is observed to be prospective for improvement of dyeability even without the assistance of salt in the dye bath for reactive dyeing. The important dyeing parameters including per cent dye exhaustion for application of different reactive dyes are assessed and compared between conventional process of dyeing bleached jute fabric (salt-soda method) and salt free acid bath dyeing of glycene modified jute fabric. Process variables for reactive dyeing at both the systems of respective fabrics are optimized and compared using different reactive dyes including a high exhaustion type reactive dye, Reactive Green HE 4BD. Colour fastness properties of dyed (for bleached and modified jute) fabrics are evaluated and observed to be at par or somewhere better for the 8% glycene modified jute fabric than normal reactive dyed jute fabric in salt-soda method. It is also observed in the present case that higher per cent dye exhaustion and corresponding higher surface colour depth are resulted for dyeing of chemically modified (glycene treated) jute fabric as compared to salt assisted exhaust dyeing of bleached jute fabric, albeit in varied percentage for application of different types of reactive dyes. Also, investigations on physico-chemical parameters and dyeing kinetics for saltfree acid bath reactive dyeing of conventionally bleached and subsequently glycene modified jute fabric using a reactive dye (Reactive Red CN) have been carried out. The important thermodynamic parameters of dyeing, such as dyeing affinity, rate of dyeing, absorption isotherms and associated thermodynamic parameters like heat of dyeing (ΔH), entropy of dyeing (ΔS) etc. have been assessed to explain the physico chemical interaction between amino-acid modified jute fibre and reactive dye system.