Natural Cellulose Fibers from Renewable Resources

Keywords

Bamboo • Renewable resource • Biofiber • Bast fiber • Alkali treatment

Considerable attention has been drawn towards the generally termed “bamboo fibers” in the last decade mainly because bamboo is a fast-growing (a meter or higher per day) biomass crop that needs minimum inputs and is renewable. How­ever, most reports or articles on bamboo fibers refer to regenerated cellulose fibers that are obtained using bamboo as a source and not the natural fibers extracted from bamboo stems/stalks. Nevertheless, natural fibers have been extracted from bam­boo, and some of the literature has been covered here despite bamboo not being a by-product and has to be grown independently. Companies are extracting natural cellulose fibers from bamboo stems and are selling them commercially. Litrax, a France-based company, is marketing “L1 natural bamboo bast fiber” that has been enzymatically extracted from bamboo stems. The extracted fibers have a linear density of about 5.2 denier and are supplied in various staple lengths up to 90 mm.

Bamboo is usually harvested after a period of 3 months and contains anywhere from 26 to 43 % cellulose, 21 to 31 % lignin, and 15 to 26 % hemicellulose [09Wai]. Fibers are extracted from bamboo using mechanical and chemical methods including enzymatic treatments [09Wai]. Bamboo chips were boiled with 4 % NaOH for 2 h under pressure to obtain fibers with lengths of 35 ± 5 mm and widths of 17 ± 3.4 ^m, but the tensile properties were not reported [10Kum]. Bamboo strips with widths from 1.5 to 1.75 cm and thickness between 0.65 and 0.75 mm were soaked with 0.1 NaOH for up to 72 h and later washed with water to obtain fiber bundles [00Des]. After the chemical separation, the treated bamboo was further subjected to mechanical separation using compression molding or roller mill techniques [00Des]. Properties of the fibers obtained using these two methods are given in Table 13.1. It should also be noted that the properties of fibers obtained from bamboo grown at different regions and age and even part of the bamboo and extraction conditions are considerably different. Bamboo fibers have

exceptional tensile properties mainly due to the unidirectional arrangement of fibrils [12Liu]. However, bamboo fibrils are arranged to the fiber axis at a low angle (2-10°) that leads to considerably low elongation of 1-2 %.

References

[00Des] Deshpande, A. P., Rao, M. B., Rao, C. L.: J. Appl. Polym. Sci. 76, 83 (2000) [09Wai] Waite, M.: J. Text. App. Text. Manag. 6(2), 1 (2009)

[10Kum] Kumar, S., Choudhary, V., Kumar, R.: J. Therm. Anal. Calorim. 102, 751 (2010) [12Liu] Liu, D., Song, J., Anderson, D. P., Chang, P. R., Hua, Y.: Cellulose 19, 1449 (2012)