レーヨンの引張強度について

Abstract

Many studies on the breaking behaviour of high polymer has been done due to its large practical meaning. But the discussion concerning the internal structure is very little due its complexity. Although, the fringe micellar structure is not accepted for all polymers at present, it is proper to think of it for the internal structure of the fiber. According to this structure, there is a wide distribution of lateral order from perfectly ordered state in the crystalline region to random state in the amorahous region. The shape of this distribution differs according to the manufacturing process. The fiber possesses a net-work structure if both ends of the chain molecule are caught in the high lateral ordered region. If some proper swelling agent (NaOH so1. for rayon) is applied to such net-work structure, it relaxes and get freed from low lateral ordered region to high lateral ordered region gradually with the increase of the concentration of the solution, and there by the junction point of the net-work structure remains in more high lateral ordered region. The tensile strength of fiber in such condition is controlled mainly by the number of chain molecules caught by the junction point. The distribution of chain length of the chain molecule caught at both ends has much influence. The maximum valus of the number of molecules in the distribution of chain lengths of chain molecule is related to the tensile strength. The amount relating to the maximum value of the chain length of chain molecule caught at both ends in the high lateral ordered region can be determined from the difference of tensile strength when the concentration of the applying swelling agent is changed. The relation between the amount related to the maximum value of chain length in the high region and lateral order can be determined. In case of ordinary viscose rayon or bemberg, a large peak in the distribution occurs at the low lateral ordered region, which shows a discontinuous state of micelle. In case of all-skin type high tenacity rayon, there is no distribution at the low lateral ordered and the distribution in concentrated highly at the right peak region of high lateral ordered region. Fortisan shows a wide distribution and is distributed up to the very high lateral ordered region. The distribution at the low lateral ordered region increases gradually with the decrease of the thickness of skin layer for four types of rayon having different ratio of skin and core. When this behaviour is compared with that of ordinary viscose rayon, discussed before, the core part is related to the low ordered region and the skin part to the high lateral ordered region. In case of all-skin type high tenacity rayon, the chain molecule is quite similar in length and the mechanical properties of it is supposed to be good due to the equal distribution of forces to each molecule. The fatigue behaviour four types of high tenacity rayon has been examined as above. Although there were differences in the fatigue life of the four types of high tenacity rayon, on such large differences of tenacity could be seen in the dry state, but there were clear differences in the swelling tensile behaviour. When the distribution of tensile strength in respect to lateral order is determined, the fiber of short fatigue life shows a large distribution of chain molecule at the low lateral ordered region, and for that of long fatigue life the distribution is large at the high lateral ordered region. In case of repeating extension, it is necessary to distribute the forces to each chain molecule effectively, and in case of low ordered region the distribution is not sufficient, while the distribution is effective in the high region and the concentration of force is avoided.