PHYSICAL-PROPERTIES OF SILK FIBERS TREATED WITH ETHYLENE-GLYCOL DIGLYCIDYL ETHER BY THE PAD BATCH METHOD

This paper deals with the epoxide treatment of silk fabrics by the pad /batch method. The optimum reaction conditions, i.e., NaOH concentrati on, and reaction temperature were 2.5 g/L and 30-degrees-C, respective ly. A weight gain of 8.5% was attained at a reaction time of 6 h. This value slightly increased to 10% after 24 h. The reactivity of tyrosin e and basic amino acid residues was dependent on the reaction time and did not significantly differ from the results of epoxide-treated silk fiber by the conventional method in tetrachloroethylene. The moisture regain slightly decreased at 4% weight gain and then increased with t he epoxide content, exceeding the value of the untreated control. The crease recovery of the epoxide-treated silk fabrics measured in the we t state was significantly improved, whereas that in the dry state was almost unchanged. The rate of photoyellowing of the epoxide-treated si lk fabrics by the pad/batch method was reduced significantly compared with that of the untreated control. Among the mechanical properties, e longation at break and tensile modulus remained unchanged, whereas the tensile strength slightly increased following the epoxide reaction. T he thermal properties were evaluated by DSC and TGA and on the basis o f the dynamic viscoelastic measurements. The DSC curve of the epoxide- treated sample showed a slight increase of the decomposition temperatu re of silk fibroin. The rate of weight loss determined by TGA remained unchanged regardless of the chemical modification, whereas the peak o f loss modulus became broader and shifted to lower temperature. The X- ray diffractograms showed that the crystalline structure of silk fiber s was not affected by the reaction with epoxides. (C) 1993 John Wiley & Sons, Inc.