抄録
The torsional angle of the fibre being twisted by the constant moment increases with the elapsed time (Torsional Creep), and decreases after removing the twisting moment as an elastic afte-effect (Torsional Recovery). The torsional creep and recovery are measured with the filament of raw silk and drawn nylon. These phenomena show the typical curves similar to the tensile creep and recovery. The instantaneous, initial twist at constant moment is followed by the creep-twist. The maximum twist attained after creep has to be reduced to the set twist for equilibrium. Considering the torsional recovery the total twist is divided into three parts; the elastic twist, the twist of retarded elasticity and the plastic twist, from which the degree of torsional elasticity and plasticity etc. are estimated. The torsional recovery of drawn nylon by simple twisting is greater than that of raw silk. Generally the torsional plasticity of fibre increases with the given twist and saturates. The number of turns T per unit length as the function of elapsed time t is represented: T=A1±B1, logt, T=A1•t±b1 or T=A0±B0 log(t+α) etc. The coefficients depend upon a given twisting moment M the plus sign corresponding to the creep, minus to the recovery. A1 and A0 are dependent on the M-T relation of the specimen, B1∞M below a certain moment, and b1 ∞1/M approximately. This study shows that the naturally stable twist of fibre changes with the time according to the above formula of the recovery of torsional deformation.
