MORPHOLOGICAL FORMATION OF THE REGENERATED CELLULOSE MEMBRANES RECOVERED FROM ITS CUPRAMMONIUM SOLUTION USING VARIOUS COAGULANTS

Morphological formation of the regenerated cellulose membranes from it s cuprammonium hydroxide solution was investigated in connection with the change in the complex Form between cellulose and cuprammonium hydr oxide and material transportation during coagulation process using var ious aqueous coagulants (H+, Na+, K+, NH4+, Ca2+, Mg2+ with various co unter ions). Scanning electron microscopically observation revealed th at the morphological distribution estimated by pore size distribution in the thickness direction of the membranes are categorized into four types (two gradient types, homogeneously dense type and skin/void type ) depending on pH and cation species (not anion species) of the coagul ants, which are in turn the determinant of water permeability of the m embrane. The each type of morphology was proved well correlated to the change in circular dichroism (CD) spectra taken for the coagulated ge ls as a function of coagulation time. which was also correlated to the transportation of ammonia and cupric ion from the original cellulose solution into the coagulants. Thus, the controlling of the morphology of the membranes from cellulose/cuprammonium hydroxide solution could be possible by simply selecting the cationic species of coagulants in general and the membrane with gradient pore distribution and having a relatively higher water permeability is obtainable by acid or ammonium salts as coagulant.