天然セルロース繊維の微細構造にいつて

第7報 酸加水分解残渣のカセイソーダ分別溶解機構と同法によるミセルの微細構造の検討

抄録

Hydrocelluose from various commercial dissolving pulps by preethanolysis for 30 minuites with 1N-HCl in absolute ethanol at the boiling point and successive hydrolysis for 30 minuites with 3.5N aq. HCl solution in a boiling water bath, were fractionated according to the sedimentation velocity in water, that is according to the size of the hydrocellulose particles, as reported in the previous paper in this series. The fractions were subjected to the fractional dissolution with aq. NaOH solutions of various concentrations at 7.6°C, in order to investigate the influence of the size of the particles on their solubility. Among the particles from a pulp, smaller particles never gave lower solubility, however smaller particles gave not always higher, but almost the same solubility in many cases. Thus, it is estimated that, in case of native cellulose micells, the fractional dissolution proceeds mainly on peeling off dissolution of the outer layer of each micell in according to the cohesive energy of each chain molecule, rather than on whole dissolution of each micell in accordance to the total cohesive energy of each micell. The fractional dissolution curves reflect strongly the mass-order distribution in the direction of width of the micell.
All micells in the pulps investigated have transitioal area in the direction of the width of the micell. The transitional area of the micells in the linters pulp consists of relatively highly ordered molecules, whereas it in the wood pulps consists of variously ordered molecules, and in the prehydrolyzed sulfate pulps it is of higher order than in the sulfite pulps. The micells in the beech pulps contain wider transitional area than those in the pine pulps. The linters pulp and the every wood pulp contain some smaller micells which are particularly rich in the transitional area, in addition to larger ones which are relatively poor in the transitional area and they form the majority.