Dyeing of sericin-modified cotton with reactive dyes

Cotton was modified with hydrolysed sericin fraction of silk in the presence of trisodium citrate as the esterification catalyst following a pad–dry–cure technique. The treatment of cotton fabric with 5% hydrolysed sericin in the presence of 7.5% catalyst followed by drying at 95°C for 5 min and curing at 140°C for 5 min produced optimum results with respect to exhaustion and fixation of reactive dyes having chlorotriaznyle and vinyl sulphone reactive groups when dyeing was accomplished in the absence of salt. Colour fastness to wash, light and rubbing of cotton for the application of reactive dyes remain unaltered for such prior modification with hydrolysed sericin. IR spectroscopy indicated the incorporation of amino acid residues of sericin fraction of silk in polymeric chains of cotton via establishment of ester linkages between carboxylic group of the amino acid moiety and hydroxyl groups of the cotton cellulose on pad–dry–cure.