Finishing of silk with EDTA under thermal treatment

Abstract

Establishment of ester linkages and relevant cross-linkages in the silk fabric by pad-dry-cure technique was studied using disodium salt of ethylene diamine tetra acetic acid (EDTA) in the presence of sodium dihydrogen phosphate, trisodium citrate, sodium formate and potassium sodium tartrate. Potassium sodium tartrate produced the most balanced effects. Treatment with 8% EDTA and 4.8% potassium sodium tartrate at 30°C followed by drying of the treated fabric at 95°C for 5 min. and curing of the dried fabric at 140°C for 5 min. produced optimum improvements in the properties such as wrinkle recovery and moisture regain with retention of 80% of original strength. EDTA cure of silk was found to be superior to conventional DMDHEU resin cure considering improvements in retentions of tenacity, tearing strength, flexibility and whiteness index for a comparable improvement in wrinkle recovery property. IR analysis indicated that potassium sodium tartrate allowed esterification of EDTA with the tyrosine and serine amino acids of silk; the said process ultimately led to some degree of cross-linking of chain polymers of silk.