Michitaka Iwata

Morphological and structural formation of the regenerated cellulose membranes recovered from its cuprammonium solution using aqueous sulfuric acid

Morphological and structural formation of the regenerated cellulose membranes from its cuprammonium hydroxide solution by acid coagulation was investigated. Scanning electron microscopic observation revealed that the morphology of the membranes changed drastically as functions of both the cellulose concentration in the original cellulose solution CCell and the concentration of sulfuric acid as a coagulant CH2SO4. It was found that at a constant polymer concentration (8 wt %) the membrane prepared by using 5 wt % aqueous sulfuric acid exhibits higher water flux, far smaller swelling anisotropy parameter Lt, and larger porosity Pr with a thinner skin structure, and these parameters were proven to be associated with lower (110) crystal plane orientation coefficient f∥(110) compared with those for the membranes obtained by aqueous sulfuric acid with more than 10 wt %. On the other hand, at constant coagulant concentration (10 wt %) the membrane prepared by using the polymer solution with 5 wt % shows far greater Pr with practically no distinct skin structure; hence, a higher flux. The drastic changes in the morphology and structural parameters as functions of CCell and CH2SO4 were found to be well correlated with abrupt changes in material transportation (copper ion, ammonium ion, and water) from the polymer solution to aqueous coagulants as a function of CCell and CH2SO4.

Change in Supermolecular Structure of Nylon 66 Fiber with Time Elapsed

ナイロン66繊維の放置過程における超分子構造, 特に結晶および無定型領域内部の分子鎖の凝集構造の経時変化について検討した.ナイロン66繊維は室内および室外に約1000日放置した.その間の超分子構造の変化は広角X線回折, 干渉顕微鏡, 動的粘弾性によって評価した.その結果, 放置時間の経過に伴ってナイロン66繊維の結晶領域においては, 結晶は大きくなり, その完全度も高くなる.また配向度は小さくなる.無定型領域においては, 放置時間の経過に伴って, 分子鎖はいったん緊張状態になり, その後緩和する.さらに900日を経過すると分子鎖の充?状態の密な部分が新たに出現する.これらの変化は室外放置試料において著しい.