抄録
The change of length of several fibers, by twisting on the usual twisting tester under various constant load, are measured by the microscope.
By twisting an amorphous rubber thread shows elongation under the low load, but an crystalline rubber thread, which is obtained by stretching more than 400-500%, shows contraction.
Similarly an undrawn nylon fiber, whose crystallites are oriented randomly in all directions, shows elongation. Isotropic filaments (undrawn nylon) are elongated progressively in several states, and are examined by twisting then under several load. In these case, we found that the elongation of the filament decreases in accordance to their degree of orientation of the crystallites and highly oriented filament shows contraction.
The two-ply yarns, composed with rubber thread or undrawn nylon fibers, show contraction by twisting, but each yarn, which are used for the two-ply yarn, tested separately show elongation.
These facts show that, by twisting, the change in length are positive or negative according to the degree of crystallization and the orientation of the crystallites parallel to the axis of the fibers.
