Effect of Hemicellulose on Paper Strength

Abstract

Studies were made of the properties of “yezomatsu” (spruce) holocellulose fibers and “yezomatsu” sulfate pulps, from which the alkali-soluble hemicelluloses were extracted with various concentrations of aqueous alkali; the relations between strength properties of the handmade-sheets and the removed hemicelluloses were investigated. The compositson of the alkali-soluble hemicelluloses was also studied quantitatively by the chromatographic method. Results were as follows :1) Swelling degree (retention of water) of pulp was proportional to the paper strength and was more affected by D.P. than by the content of hemicelloses. It may be possible to some extent to estimate the strength properties by determining the amount of water which is separated from the swelling pulp by the centrifugal method.2) Breaking length and bursting strength increased with the amount of retained hemicelluloses. A certain hemicellulose (such as xylan, mannan) did not seem play any effective role relative to the strength properties of paper.3) Over-all strength of paper was high when the hemicelluloses were partially removed from the pulp with aqueous alkali (e. g., ca. 0.5%).4) The ratio of static strength (breaking length, bursting strength) and dynamic strength (tearing strength, impact strength) of paper can be controlled by the amount of the hemicelluloses retained in the material.