On the Determination of Fine Structure of Cellulosic Fibers

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Abstract
In order to clarify the fine structure of rayon staple, it may be necessary to estimate not only the total crystallinity but also the distribution of crystalline size and quality. For this purpose, various methods which seemed to remove the amorphous region without recrystalliza-tion, were studied. Methanolysis is affected by water content in the mixture and its residue may still contain an amorphous region because of its high accessibility. The recrystalli-zation may be possible during not only hydrolysis but also methanolysis. The hydrolysis after pretreatment is not very effective to prevent recrystallization and may destroy crystalline region. Moreover, its procedure is troublesome. The oxidizing-hydrolysis, which shifts the crystalline length distribution toward slightly higher DP region diminishing the shoulder on higher DP side and gives the lowest levelling-off accessibility, holds out considerable promise for the elucidation of the original crystalline structure. But its high solubility in alkaline solution may be derived from a carboxyl group formed during oxidation or from the cracks in a hydrogen-bond train of crystallites. Therefore, problems to study still remain. The crystalline region of viscose rayon staple seems to have the chain-length distribution, which extends to a DP of ca. 40 and shows one maximum between the DP of 6 and 10.