Chitin fibres

Results were obtained on the calcium phosphate growth on phosphory-lated chitin fibres using the urea/H3P04 method and subsequently soaked in saturated Ca(OH)2 solution and in simulated body fluid solution. 

To obtain the phosphorylated chitin, fibres were soaked in saturated Ca(OH)2 solution (pH 12.4) for 8 days. The Ca(OH)2 solution was renewed every 4 days. After completion of the soaking period, the fibres were washed, filtered and dried under vacuum at 60 °C. This technique of phosphorylation and Ca(OH)2 treatment has been found to be a useful method for creating favorable local conditions leading to the nucleation and growth of calcium... 

Cross-linking agents have been proposed for the improvement of chitin fibres in the wet state. Epichlorohydrin is a convenient base-catalysed crosslinker to be used in 0.067 M NaOH (pH 10) at 40 °C. The wet strength of the fibres was considerably improved, whereas cross-hnking had neghgible effect on the dry fibre properties. Of course, the more extended the chemical modification, the more unpredictable the biochemical characteristics and effects in vivo. Every modified chitin or modified chitosan fibre should be studied in terms of biocompatibiUty, biodegradabiUty and overall effects on the wounded tissues. 

Figure 19.7 Molecular correspondence of the inorganic-organic interface in the nacreous shell layer of Nautilus repertus. (a) Structural relationships between protein sheets, aragonite crystals and chitin fibres, (b) Possible complementarity of Ca binding. (From Mann et al., 1989. Reproduced with permission from John Wiley Sons., Inc.)...

Hirano, S., Zhang, M., Chung, B.G., and Kim, S.K. 2000. The A-acylation of chitosan fibre and the A-deacetylation of chitin fibre and chitin-cellulose blended fibre at a solid state. Carbohydr. Polymers 41, 175-179. 

Fig. 4.10. Schematic representation of the structural relationships between protein sheets, aragonite crystals, and chitin fibres in the nacreous layer of N. repertus ...

The growing tip of a hypha is thin walled and capable of very rapid extension it shows plastic rather than elastic deformation. In some species, such as many of the Mwcora/es glycosylated material is shed around the growing tip. Near the tip the wall already has a meshwork of chitin fibres on its inner face, probably overlain by protein or glycoprotein. 

Regenerated chitin derivative fibres were used as binder in a paper-making process. N-iso-butyl chitin fibres were added at 10 % yield to reinforce the breaking strength of paper [97,98]. Chitin fibres and/or chitosan fibres with diameter <100 nm and an aspect ratio >5 were used in pneumatic tires and give a good abrasion resistance [99]. 

Li, XM., Feng, QL., Liu, XH., Dong, W., Cui, FH. 2006. Collagen-based implants reinforced by chitin fibres in a goat shank bone defect model. Biorrmterials 27 1917-1923. 

The COOH group is also effective for apatite nucleation, as described in Section 14.1.6. Alginic acid possesses the COOH group in its structure, as shown in Figure 14.1.22. Therefore, its fibres form bone-like apatite on its surface in an SBF within 7 days, when they are previously treated in an aqueous saturated Ca(OH)2 solution, as shown in Figure 14.1.22 (Kokubo, unpublished). Chitin fibres can be modified to form COOH groups on their surfaces by car-boxymethylation. They also form apatite on their surfaces in an SBF within 7 days, when they are previously treated in an aqueous saturated Ca(OH)2 solution [63]. 

The nonwoven fabric made from chitin fibres and atelocollagen filaments can be used as an artificial skin for treating bum wounds (Anandjiwala, 2006 Yoshito, 1989). A nonwoven fabric of regenerated collagen has been commercialized for wound covering. Chitosan fibres are of particular interest due to their large surface... 

Industrial separation membranes and ion-exchange resins can be made from chitin, especially for water purification. Chitin is also used industrially as an additive to thicken and stabilize foods and pharmaceuticals. Since it can be shaped into fibres, the textile industry has used chitin, especially for socks, as it is claimed that chitin fabrics are naturally antibacterial and antiodour (www.solstitch.net). Chitin also acts as a binder in dyes, fabrics and adhesives. Some processes to size and strengthen paper employ chitin. 

Many water-soluble polysaccharides can be induced to orient themselves in a single direction by annealing and pulling spun fibres in a certain direction, and many natural linear polymers (such as cellulose or chitin) are biosynthesised partly crystalline. 

Adsorption Cellulose, chitine (chitosan), nylon, polypropylene fibres, polymer nets and membranes, wood, lignine, ion-exchange resins, polyurethane foam, polyacrylamide (Porous) glass, clay,bentonite, zeolithes, ceramics, meso-porous silica, metal oxides (Fe, Ti, Mg), metal phosphates, mineral powder... 

Over 150,000 tonnes of chitin is currently harvested by utilising a by-product of the seafood industry, making it available throughout the year. Chitin and CS are currently in the spotlight due to their numerous applications in biomedicine, waste water treatment, food, cosmetics and the fibre industry [35-39]. The high nitrogen... 

Jajpura, L., Harad, A, and Maitra, S., Chitin and chitosan in antimicrobial composite fibres, Asian Text.15(2], Feb(2006), 55-58. 

Fibres were first developed by Austin [60] and then by Hirano [61-63] in solvents mentioned previously, especially the DMAc/LiCl system. The fibres were obtained by wet-spinning [63]. A recent review presents the different fibres obtained from chitin solution and some of their physical properties [27]. In addition, chitin solutions may be casted to obtain films [64,65] or regenerated under sponge or bead conformation in dependence of the use. Fibres were often proposed for textile applications [66-68]. 

Blends were prepared with cellulose or silk as soon as a common solvent was available [63, 69-71]. Recently, ionic liquids were used. The solvent l-ethyl-3-methyl-imidazolium acetate completely dissolves raw crustacean shells allowing to recover high purity chitin powder or films and fibres by direct spinning [72]. Films of poly(e-caprolactone) (PCL) blends with a-chitin and chitosan were produced. They are completely biodegradable and the crystallinity of PCL is suppressed in the blends due to hydrogen bond interaction between PCL and polysaccharides [73]. Blends were also realized with poly (3-hydroxybutyric acid) (PHB) and chitin or chitosan. They show faster biodegradation than the pure-state component polymers [74,75]. 

Blends or composites were also prepared especially by Hirano in the same way as mentioned previously for chitin [63], Other systems were proposed in the literature and listed previously [1, 2], Some of them are described in detail, for example, chitosan/ polyamide 6 and chitosan/polyamide 66 [119,120], chitosan/cellulose using a common solvent [121,122], chitosan/poly(oxyethylene) (POE) [123], chitosan/polyvinylpyrrolidone (PVP), chitosan/polyvinyl alcohol (PVA) [123,124], chitosan/polycaprolactone [124-126], chitosan/ collagen [127], chitosan/PHB [128], and chitosan/cellulose fibres [129]. In some case, the polymers are crosslinked in the blends [130]. Hydrogels or films have been prepared by mixing chitosan solution with monomers, initiator and cross-linker followed by copolymerization [131,132]. 

In this chapter, the characteristics of chitin were described. This was followed by a discussion on the solubilization necessary to process the polysaccharide to obtain new materials. Its fibre and Aim-forming performances are recognized and allow application in the texAle domain or in packaging. Nevertheless, the more important applications are in the domain of biomaterials due to the hydrophilic character and antimicrobial properties. 

Hirano, S., Nakahira, T, Nakagawa, M. tind Kim, S.K. (1999) The preparation and applications of functional fibres from crab shell chitin. Journal of Biotechnology, 70,373-377. 

Fibrous fillers for biomedical PLA-based FRPs include carbon and inorganic fibres [406], PLLA (i.e. self-reinforcement) [407,408], poly(p-dioxane) fibre [409], chitin [410], biodegradable fibre (e.g. bioactive glass, chitosan fibre, polyester amides) [411], hydroxyapatite fibre [412], hydroxyapatite whiskers [413], halloysite (Al2Si205(0H)4) nanotubes [414] and the fibre from different tissue types of Picea sitchensis [415],... 

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