Fiber from chitins, chitosans

The subject of fiber production from chitin and chitosan has been reviewed considering the interest in the exploitation of chitin as a textile material [246-251]. The production of fibers, however, is a challenging and difficult task. 

We used the crosslinked chitosan fiber (hereafter called ChF) in this experimental study. ChF was fabricated by Fuji Spinning Co., Japan. Fig.l shows the unit molecular structure of chitosan which was transformed from chitin by deacetylation. Chitin is a natural biopolymer which is contained in the shell of arthropods. Chitosan was crosslinked to make an adsorbent with acid, alkaline, and chemical proofs. The fabrication method of ChF was presented elsewhere.[S,6]. 

FIGURE 20.2 Changing of blood pressure by intake of high salts and dietary fibers in rats, o, , normotensive rats a, a, SHRSP o, a, alginic acid diet , a, chitosan diet. (From Okuda, H. et al., J. Chitin Chitosan, 2, 49, 1997.)... 

Chitosan is the deacetylated derivative of chitin, which is the second most abundant natural polymer and exists widely in cell walls of fungi and crustacean shells. Chitin is known to have accelerating effects on the wound-healing process, and fibers, mats, sponges, and membranes have been made from chitin for use as wound-dressing materials. 

Pulpura S. Kohn J. J. Biomaterials Applications, 1992, vol. 6, pp 229. Hiroshi, S. Mitsuhashi, K Tanibe, H. In Antibacterial and Anti ngal Fibers Blended by Chitosan. Brine, C., Ed. Advances in Chitin and Chitosan Proceedings from the 5" International Conference on Chitin and Chitosan Elsevier Applied Science, London, 1992, pp 34-40. 

Crystalline, flake chitosan from King crab exhibited patterns similar to those of chitin, but the 002 peak (b is the fiber axis) shifted from 0.962 nm for chitin to 0.857 nm for flake chitosan. The position of this peak depends on the content of water and is lowered to 0.745 nm on drying at 134°. It was postulated that water molecules that enter the lattice are loosely bound between the chains along the 001 direction. 

Chitin is known to be biodegradable, biocompatible, and nontoxic. It is used in dmg delivery and bio medical applications. It also used in the purification of water especially for the absorption of toxic dyes. Chitin has limited solubility in solvents but chitosan is readily soluble in acidic aqueous solutions and has more tendency to be chemically modified. Chitosan can readily be spun into fibers, cast into films, or precipitated in a variety of micromorphologies from acidic solutions. Min and Kim have reported on the adsorption of acid dyes from wastewater using composites of PAN/chitosan [52]. Shin et al. has reported on copolymers composed of PVA and poly dimethyl siloxanes cross-linked with chitosan to prepare semi IPN hydrogels for application as biomedical materials... 

Chitosan is a fiber produced by hydrolyzing chitin, mostly from crustaceans [86]. 

The x-ray fiber diffraction data of chitosan was first derived from the solid-state deacetylated product of a lobster tendon chitin by Clark and Smith (1936). Sixty years later, Okuyama et al. (1997) analyzed the pattern of tendon chitosan. In the tendon polymorph, the chitosan chains and water molecules are packed in an orthorhombic unit cell. Each chitosan chain takes an extended... 

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