Chitin, Chitosan, and Alginate Fibers

Keywords

Chitosan • Ionic solvent • Wet spinning • Dry spinning • Chemical modification • Chitosan • Blend fiber • Chitosan fiber cross-linking

Chitosan has been extensively studied for the production of fibers, and the fibers developed have been thoroughly characterized for their structure, properties, and potential applications. One of the major advantages of using chitosan for fiber production is the solubility of chitosan in common solvents that are relatively inexpensive and environmentally friendly. Table 25.1 lists the most common solvents that have been studied for dissolving chitosan. In addition to the solvents, several other parameters have also been reported to influence the properties of chitosan fibers produced. El-Tahlawy and Hudson studied the effect of various spinning parameters on the production and properties of chitosan fibers [06El]. They reported that viscosity of the solution was critical for fiber production and that adding salt such as sodium acetate assisted in controlling the viscosity, draw ratio, and therefore fiber properties. Similarly, it was reported that the process used to dry the fibers after coagulation also influenced fiber properties. Drying in a methanol coagulation bath provided fibers that could easily separate from each other and have a smooth surface and higher mechanical properties than direct, radiant, or forced air heating [98Kna]. The effect of demineralization time and temperature on the properties and biodegradation of chitosan fibers was investigated by Judawisastra et al. [12Jud]. It was reported that demineralization caused degradation of the polymers and led to an increase in the diameter of the fibers, reduced tenacity by 52 %, and increased elongation (136 %). Biodegradation of the fibers in a phosphate-buffered solution containing 2 % lysozyme increased by 17 %. Similarly, ripening of chitosan dissolved in acetic acid was found to substan­tially affect fiber properties [03Lee]. Increasing ripening time continually decreased tenacity and modulus but increased elongation. Thermal analysis showed that the

peak temperature and thermal degradation temperature decreased with an increase in ripening time.