天然セルロース繊維の微細構造について

第3報　酸加水分解中に起こる結晶化のアルコリシス前処理による防止

抄録

It is expected that recrystallization during acid hydrolysis of cellulose fibers can be inhibited to some extent by previously increasing accessibility of the fibers to acid hydrolysis, that is by splitting of the chain molecule and degradating of the morphological structure without rearrangement during the pretreatment. The effect of prealcoholysis as the pretreatment was investigated.
A commercial viscose grade pine sulfite pulp was prealcoholyzed with 1.0 N-HCl in absolute methanol, ethanol, and n-propanol at the boiling point respectively, washed, and then without drying, subjected to acid hydrolysis with 3.5N-aq. HCI at 100°C. Amount of highly ordered regions (crystallinity estimated by acid hydrolysis method) and leveling off degree of polymerization were determined to compare the inhibiting effects of alcohols.
Prealcoholysis is effective for inhibiting recrystallization during acid hydrolysis. Among the three, ethanolysis is most preferable for the purpose, at least practically, because methanolysis seems to allow considerable recrystalliztion by itself. Propanolysis may proceed in excess topochemically, and besides propanolyzed residues retains brown color even after the successive hydrolysis is applied. It was sufficient to preethanolyze for 30 min. under the experimental conditions. Prealcoholysis is effective also to prevent humification during hydrolysis.
Hydrocellulose obtained by preethanolysis for 1/2 hr and successive hydrolysis for 1/2 hr contained no molecule of degree of polymerization over 300, while hydrocellulose obtained by hydrolysis for 2 1/2 hr without the pretreatment contained molecules of degree of polymerization over 500.