Fibers from chitin and chitosan

As mentioned before, it is essential that a stable chitin solution form in order to spin the chitin fibers. There is a long history of attempts to find stable 

Austin suggested organic solvents containing acids such as chloroethanol, sulfuric acid and trichloroacetic acid (TCA) for the direct dissolution of chitin in 1975 [23]. A filament was extmded from the spin solution made with chitin in a mixture of 40% TCA, 40% chloral hydrate, and 20% methylene chloride. The filaments were solidified in the coagulating bath containing acetone, neutralized with potassium hydroxide (KOH) in 2-propanol followed by washing in deionized water, and, then, cold drawn. Other solvent systems for chitin have been proposed [24]. However, they require fairly drastic conditions to dissolve chitin and some are very corrosive or expensive. It is hard to maintain the chitin molecule without depolymerization during the dissolution process. 

Chitosan has also been used to prepare coated or bicomponent filaments. A chitosan-coated alginate filament was successfully prepared by the addition of a small amount of chitosan to the first coagulation bath containing the calcium chloride dihydrate saturated methanol solution. Touch and feel as well as mechanical properties of the alginate filament were improved by 

Other researchers in addition to Hirano have extensively studied the production of various chitin, chitosan, their derivatives, and composite fibers with other polymer materials, since 1994. Their spinning solution, coagulating solution, and polymer materials used in the dope are summarized in Table 12.3. Rathke and Hudson s review concerning chitin, chitosan, and their derivatives covers all of the reported information up to 1994 [24]. 

Sodium chitin xanthate-silk fibroin Sodium cellulose xanthate-silk fibroin Sodium /V-acetyl xanthate-sodium cellulose xanthate Sodium /V-aceylation salts-sodium cellulose xanthate 

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