Abstract
Changes in fibre structure of cellulosic materials such as degree of crystallinity and lateral order and system of cavities during cold-extraction with caustic solutions of various concentrations and during subsequent drying under various conditions have been investigated experimentally.It has been found that if cellulosic materials are treated with caustic soda solutions of over certain concentrations, the amount of amorphous region increases at the expense of highly ordered region. These limiting concentrations at 20°C., are 10-12% for cotton linter, and 8-10% for wood pulp. The increased amorphous region, if dried under below 80% RH, becomes “horny” and losses capability of reaction that is completely recovered by wetting with water.Lateral order distribution was estimated from the solubility of the residue in caustic soda solutions of various concentrations after the leveling-off degree of polymerization has been attained by acid hydrolysis.Relative pore sizes of fibre texture were determined by measuring the dye-uptake from unswollen medium.
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