再生セルロース繊維の湿潤時の粘弾性

抄録

The relation between the fine structure of the fibers and their mechanical properties is much interesting. Depending on the utility, there are many chances for the fibers to be placed in high temperature and in the wet state. To obtain a fundamental knowledge of this, it is necessary to do the measurement of the viscoelastic behaviour of the fibers in the wet state at various temperatures. There are many researches of Clark etc., on the physical properties of the regenerated cellulose fibers in the wet state at various temperatures, and that of Wakeham etc., on the relation between tension and temperature. In this research the mesurement has been performed in water at low freqency by varying temperature and the dependency of longitudinal dynamic modulus, longitudinal viscosity, and tan delta with temperature and their relation with the fine structure of the fibers have been investigated. Fortisan, bemberg, viscose rayon, high tenacity rayon, cellophane, and gel-cellophane were used as samples. The aggregate state of these samples were estimated by Maeda's method and to determine the relation between the aggregate state and the orientation of the part, which has much influence on the effect of mechanical properties, the measurement of swelling and contraction was performed. When the relation between the orientation and the aggregate state is determined, it is observed that Fortisan possesses a good orientation in the state of high order and high tenacity rayon possesses orientation in low order. Although viscose rayon and bemberg possess little orientation, bemberg has orientation up to high order. The fine structure and the viscoelastic properties of these fibers were compared. The method of measuring dynamic properties was that wire strain gauge was used for the measurement of tension and strain and each wave was recorded in the oscillograph. Lissajous' figure of the relation between stress and strain was drawn from these wave forms. The speed of the cycle was 9.8 second and the applied strain was 0.4%. The shape of the hysteresis loop satisfies the linearity approximately. Gel-cellophane shows the lowest value for the longitudinal elastic modulus and cellophanes of lateral and longitudinal directions follow it. The influence of temperature in cellophane is small and there was not much large difference. The effeect of orientation on the elastic modulus is the most large one. The degree of change of modulus in high tenacity rayon is considerably large and it shows the large temperature dependency in the place of low aggregate state. The temperature dependency of the modulus of Fortisan was simple and there was no change point. The temperature dependency and sample dependency of the energy loss derived from hysteresis loop resemble well with the temperature dependency of the longitudinal elastic modulus. The energy loss of Fortisan was most large and was minimum in the case of gel-cellophane. It may be that tan delta varies with the aggregate states rather than orientation. The difference due to direction in cellophane was not observed. With the increase of water content in the regenerated cellulose fibers, the temperature dispersion of tan delta shifts gradually towards low temperature or it may be that the dispersion of tan delta exists below those temperatures. This tendency was approximately same for every regenerated cellulose fibers. The dynamic longitudinal viscosity was determined from the width of the loop and its temperature dependency was observed. At low temperature the effect of hydrogen bond between the cellulose molecules may be dominating, and at high temperature the effect of more weak secondary bond force of the amorphous parts of cellulose fiber may be perceived. The temperature dependency of dynamic behavior of heat treated Fortisan appears some change to untreated case and for H.T. rayon the effect is little.