DISSOLUTION OF NATURAL CELLULOSE INTO AQUEOUS ALKALI SOLUTION - ROLE OF SUPER-MOLECULAR STRUCTURE OF CELLULOSE

An attempt was made to explain the dissolving behavior of natural celluloses in aq. alkali solution in terms of super-molecular structure. Cellulose samples with crystal form of cellulose I having the viscosity-average molecular weight of ca. 8 x 10(4) and having various solubilities were prepared by applying the methods of so-called steam-explosion treatment and acid-hydrolysis to soft wood pulp and cotton linter. Their solubility towards aq. NaOH solution proved to be governed by the degree of break-down of O3-H...O'5 intramolecular hydrogen bond chi(am)(C3) as previously demonstrated for regenerated celluloses. chi(am)(C6) expressing in part the degree of break-down,of O2-H...O'6 intramolecular hydrogen bond was shown to be also closely correlated with the solubility of the cellulose. In addition to chi(am)(C3) and chi(am)(C6), several other super-molecular structural parameters estimated from the infrared spectra of the natural cellulose samples were found to be correlated with solubility and those parameters might represent wide variation of conformation caused by the break-down of intramolecular hydrogen bonds.