Page 312 - Advances in Textile Biotechnology

Chitin, chitosan and bacterial cellulose for textiles 293

to 70% of the original water content by re-swelling. Through a stepwise
exchange of water for other solvents, it is possible to introduce into bac terial
cellulose methanol, acetone, or n-hexane in the same volume as water, while
maintaining the hollow space and network structure (Klemm et al., 2005;
Schrecker and Gostomski, 2005).

12.3 Basic principles, methods and technologies
The optimal biopolymer production process should be environmentally
clean and feasible for large-scale production at an acceptable cost. In the
following, progress in chitin, chitosan and bacterial cellulose fi bres produc-
tion is summarized.

12.3.1 Chitin and chitosan fi bres production

Several methods for chitin and chitosan production from microbial sources
such as Allomyces, Aspergillus, Penicillium, Fusarium, Mucor and Rhisopus
are known (Allan et al., 1978; Knorr and Klein, 1986; Muzzarelli et al., 1980;
White et al., 1979). However, these techniques are not currently used on an
industrial scale. The conventional way to produce chitin from common
sources, e.g. crab and shrimp shells, includes an extraction process to remove
the minerals, typically calcium carbonate, followed by repeated treatments
with a dilute alkali solution to remove the proteins from the shell wastes.
A bleaching process is usually involved to remove the pigments. Commer-
cially, chitosan is produced by chitin deacetylation with concentrated alka-
line solutions at elevated temperature. During this process, the acetamide
groups of chitin undergo hydrolysis and chitosan is formed. Several com-
panies including France Chitine (www.france-chitine.com), Primex (www.
primex.is) or Heppe Biomaterial (www.biolog-heppe.de) are using these
processes for chitin and chitosan production, and the Belgian company
KitoZyme (www.kitozyme.com) uses renewable fungal resources to produce
chitin and chitosan. This process permits excellent control of the molecular
characteristics, in particular the degree of deacetylation and the molecular
mass (length of polymer chains) of the biopolymer.
Research on fibre fabrication methods has attracted interest from both

academia and industry. Several fabrication techniques such as spinning
techniques, melt-blown, phase separation and self-assembly have been

employed to produce fibres suitable for various purposes (Zhang et al.,
2005). Fibres based on chitin and chitosan have been known for a long time
and, in the early stages of man-made fibre development, much of the atten-

tion was focused on a chitin as a potential raw material for making artifi cial
silk. This resulted in many attempts during 1920s and 1930s to produce
chitin fibres from a number of solvent systems. Only after recognition of

© Woodhead Publishing Limited, 2010