Fiber structure and swelling behavior of domestic silk fibers(Bombyx man) treated with a mixture of glyoxal and urethane resins were investigated. The amino acid composition of the hydrolysate solution of the resin treated fibers indicated that the glyoxal monomer reacted with the tyrosine residue. For the glyoxal resin with rel atively large number of hydroxyl groups per glyoxal monomer, the fixation of the resin to the amorphous regions of the fibers was promoted and the crystallites with

more »

... ler sizes were destroyed. However, if the number of hy droxyl groups was relatively small, the degree of swelling of the amorphous regions decreased although the amount of the resin fixed in the fibers was small. The decrease in the absorption of water by treating the fibers with a mixture of glyoxal and urethane resins was considered to be caused by the crosslinkings formed in the fi bers.