Ikuya Miyamoto

Blend membranes from cellulose/konjac glucomannan cuprammonium solution

Abstract The blend membranes were prepared from cellulose/konjac glucomannan (KGM) cuprammonium solution by coagulating with aqueous 10 wt% NaOH solution, 20°C and 40°C water, respectively. Miscibility, pore morphology, structure, water permeability and mechanical properties of the blend membranes were investigated. The complex forms of cellulose/KGM in the mixed solutions, the effect of various coagulants and the percent content of KGM ( w KGM ) on the structure and properties of the blend membrane are discussed. SEM and mechanical relaxation analysis indicate that the blend membranes are miscible in the range of 0–30 wt% of w KGM . When w KGM was smaller than 20 wt%, the tensil strength of the blend membrane coagulated by alkali aqueous solution was enhanced, corresponding to homogeneous structure and small pore size. However, blend membranes having a larger pore size (366 nm by SEM) and water permeability (560 ml/m 2 h mmHg) were obtained by coagulating the cellulose/KGM (70:30) cuprammonium solution with 40°C water, where ca. 20% of KGM as pore former were removed from the membrane.

Formation Mechanism and Structure of the Gel Obtained from Cellulose/Cuprammoniurn Solution

目的 本研究ではセルロース/銅アンモニア水溶液から湿式凝固で得られる凝固ゲルの構造および構造形成過程を明らかにするため, この系の相図を作成し水, アルカリ添加および温度変化による凝固過程での錯体構造, 粘弾性変化について検討した.結果 (1) 40℃での銅・セルロース/アンモニア/水系の相状態はその組成によって変化し, 溶液相, ゲル相, 固液相の3っの相をとる. (2) 昇温によって特定組成のセルロース/銅アンモニア溶液はゲル化するが, その際銅とセルロースの2, 3位の水酸基とのキレート配座が崩壊し, セルロ-ス分子間で水素結合が形成する. (3) 水およびアルカリによる湿式凝固の初期過程はゲル化によって進行するが, 凝固剤によってゲル化の速度, 得られるゲルの錯体構造および粘弾性は大きく異なる. (4) 水凝固で得られるゲルは昇温ゲルと同様分子間水素結合による弾性率の低い架橋形態であるが, アルカリ凝固の場合は銅を含む化学架橋によって弾性率の高いゲルが得られる.