By combining an 8mm movie camera with the counting tube resilince meter, the energy loss per cycle of of nylon, Terylene, and rayon yarns and cords are measured at the neighbourhood of initial severel cycles, 10, 100, 500 and 1000 cycles. The strains are 1% and 3%. The applied strain is of constant rate of deformation type, while the speed is cycle per second. The results are obtained as follows.
1. Except Terylene, others show decrease of hysteresis loss with an increase of repeated number of elongation. The decrease is rapid at 2_??_3 cycles, and if the repeated number of cycles are converted to logarithm, this may be shown by an approximate straight line. At severel cycles, the fibers and cords are stabilized considerably.
2. With the increase of temperature, the hystersis loss decreases in the case of nylon and this is in opposite to the result, derived by Wakeham. As the effect of humidity is large in rayon, the result is not definite, due to its mutual effect with temperature. Terylene showed a little decrease with the increase of temperature.
3. Comparing the stabilized and unstabilized nylon cords, the effect of stabilization is low at 1% of strain, but at 3% the property of recovery is high in the case of treated cord. The treated cord is also stable in respect to the change of temperature.
4. The minimum point of the hysteresis loss of Terylene appears at 2_??_3 cycles. This is explained as due to the change in the internal structure.
5. Though the effect of twist is complicated due to the change of strain for twisting and the friction with inter fibers, the decrease of hysteresis loss is observed as nylon twisting is increased. This change in rayon is complicated.
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