Manufacture and physical properties of alginate fiber papers as an analysis model of cellulosic fiber papers

Abstract

AbstractThe staple fibers of Ca alginate or alginic acid were found to have interfiber self‐bonding, which allowed us to make papers composed of fibers with homogeneous fiber diameter and fiber length without binders. The analysis of the effect of the molecular weight (MW) and fiber diameter on physical properties of the sheets showed that strength factors, except zero span breaking length and tear index, increased with increase of MW of alginic acid up to 6 × 105 dalton. The folding endurance was the most sensitive to MW, requiring a MW of 5 × 105 dalton or higher to reach the level of 10 folds. The breaking length of alginate fiber papers ranged from 2.0 to 3.5 km and was higher than that of the corresponding free acid fiber sheets. Investigation of the effect of fiber length indicated that the folding endurance increased almost linearly with increase in fiber length but that the breaking length and tear index were maximum at a fiber length of 3.0 mm, suggesting that these factors were mainly influenced by sheet formation. The paper formability of the metallic salts of alginate fiber was as follows: Ca2+ > Ba2+ > Al3+ > > Fe3+. The admixture of acidic polysaccharides, such as pectin and κ ‐carrageenan with Na alginate, also made it possible to spin continuous yarn. Papers obtained from the admixed fibers had higher bulk density and Young's modulus by 1.5–1.8 times and were very transparent, just like glassine paper. X‐ray microanalysis showed that the Ca alginate fiber had no skin‐core structure, homogeneously distributing Ca2+ in whole fiber.