INFLUENCE OF SWELLING OF NONCRYSTALLINE REGIONS IN SILK FIBERS ON MODIFICATION WITH METHACRYLAMIDE

The degrees of swelling of noncrystalline regions of domestic and tuss ah silk fibers were investigated by measuring the small-angle X-ray sc attering intensity of the fibers in wet conditions and analyzing the s cattering intensity based on a two-phase model, i.e., crystalline regi ons and water-swollen noncrystalline regions. The influence of the deg ree of swelling of noncrystalline regions on the graft treatment of th ese fibers with methacrylamide was investigated. The changes in the st ructure caused by the graft treatment were also analyzed using the wid e-angle X-ray diffraction measurements. As compared with the tussah si lk fibers, the domestic silk fibers showed a larger degree of swelling of the noncrystalline regions, and gained a larger amount of resin by the graft treatment. The crystallites with smaller sizes in the tussa h silk fibers were destroyed preferentially by the graft treatment. Fo r the domestic silk fibers, the crystallites were destroyed more serio usly and rather homogeneously independent of the crystallite sizes. (C ) 1996 John Wiley & Sons, Inc.