Structural studies of binary blend fibers of nylon 6 and nylon 66 by meansof WAXD, SAXS, and DSC

Measurements of wide-angle X-ray diffraction (WAXD), small-angle X-ray scat tering (SAXS), and differential scanning calorimetry (DSC) were performed o n binary blend fibers of nylon 6 and nylon 66 prepared by drawing and annea ling of melt-spun blend fibers. To detect coexisting crystalline phases of both nylon components, we developed a procedure to distinguish alpha-form c rystals of nylon 6 and nylon 66 in their mixtures by utilizing higher-order diffraction spots of WAXD far the alpha-form crystals, and applied it to n ylon 6/nylon 66 blend fibers over the whole range of composition. Nylons 6 and 66 thus crystallize separately and form individual crystallites of thei r respective alpha-form crystal structures. By analyzing data of DSC diagra m, the appreciable depression of the total degree of crystallinity of both components observed in the intermediate range of composition for unoriented mixture samples reported previously, is almost recovered for drawn and ann ealed samples treated in this work. The development of crystalline slate in the blend fibers brought about by drawing and annealing was confirmed by c hanges of profiles of SAXS diagram. This tendency is more prominent in nylo n 6 rather than nylon 66. The cause for this is discussed.