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Home  >  Journal list  >  Polymer Journal  >  Vol.28  No.9 (1996)  >  pp.769-779

Polymer Journal
<<Previous article Vol.28  No.9 (1996)   pp.769 - 779 Next article>>

Super-Molecular Structures Controlling the Swelling Behavior of Regenerated Cellulose Membranes

Tomoko Hongo (née Hirasaki)1), Chihiro Yamane1), Masatoshi Saito1) and Kunihiko Okajima1)
1) Fundamental Research Laboratory for Natural & Synthetic Polymers, Asahi Chemical Industries Co., Ltd.

ABSTRACT:  Swelling behavior of the regenerated cellulose membranes prepared from cellulose solutions dissolved in aqueous cuprammonium hydroxide and in dimethylacetamide/lithium chloride by various coagulation systems was discussed with special emphasis on crystal plane orientation and amorphous structures characterized by mechanical relaxations. Swelling anisotropy Lt to thickness direction of the membrane was observed without exception and was found to be categorized into three groups due to coagulation systems (acid, alkaline, and organic systems). Acid coagulation system was omitted from discussion because of discussion elsewhere. Lt was well correlated with crystallinity χc and its (110) plane orientation parameter f||(110), showing that larger those values give larger Lt. Larger Lt (hence, larger χc, or larger f||(110) in turn was confirmed to be related with higher Tmax for α2 and lower αH2O, β, and γ relaxations, and with larger tanδmax for all relaxations. These results lead to a conclusion that higher order molecular packing (stronger intermolecular hydrogen bonding) including crystalline part might accompany with the amorphous structure having more mobile local segmental motions during membrane formation studied here. Of these relaxations, β relaxation was confirmed to be composed of two mechanical relaxation mechanisms, one associated with out-of-phase local motion against (110) plane-like structure and the other associated with in-phase segmental motion. The swelling anisotropy was tentatively concluded as a phenomenon that arises from water penetration to more mobile parts, plasticizing molecular chains and integrating some of them along originally existed elementary crystals to the plane orientation direction according to f||(110), or simply rearranging the elementary crystals to the thickness direction, and of course water is retained between them.


Keyword:
Swelling Anisotropy/ Plane Orientation/ Mechanical Relaxation/ Regenerated Cellulose/ Membrane Formation/ Amorphous Structure

Published online: April 02, 2005
© Copyright, 2005 by The Society of Polymer Science, Japan

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