Fiber Production Using Alkali System


A simple approach to producing regenerated cellulose fibers was to dissolve cellulose pulp using alkali. The principle and mechanism of dissolving cellulose in alkali solutions are depicted in Figs. 16.1 and 16.2. It has been proven that the solubility of cellulose in alkali solutions is mainly governed by the degree of breakdown of the intramolecular hydrogen bonding and also by the degree of polymerization [92Kam, 98Iso]. The presence of lignin was found to lower dissolution, whereas the extent of hemicellulose did not affect the solubility [98Iso]. Several authors have used alkali solutions to produce regenerated cellulose films and fibers using cellulose from different sources [92Kam]. Alkali-soluble cellulose was prepared by exploding softwood pulp (DP of 331) with steam, and later, the pulp was dissolved in 9.1 % of NaOH precooled to 4 °C and used to extrude fibers. Fibers were produced with a fineness of 53–84 denier and had % crystallinity between 65 and 67 %. The tensile strength of the fibers varied from 1.5 to 1.8 g per denier, and the elongation was between 4.3 and 7.3 % depending on the conditions used during coagulation [92Yam]. Similar to the NaOH/urea system, the alkali system of dissolving cellulose was also limited by the degree of polymerization. Cellulose with relatively high DP (850) had limited solubility (26–37 %) in the alkali solutions [98Iso, 08Wan]. Contrarily, rayon which has a lower DP, poorly ordered crystalline region, and weak hydrogen bonding completely dissolved in alkali solutions [90Yok].

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Fiber Production Using Alkali System
Book Title
Innovative Biofibers from Renewable Resources
Regenerated Cellulose Fibers
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Chapter DOI
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  • Narendra Reddy (3)
  • Yiqi Yang (4)
  • Author Affiliation
  • 3 Centre for Emerging Technologies, Jain University, Bangalore, India
  • 4 Department of Textiles, Merchandising and Fashion Design, University of Nebraska-Lincoln, Lincoln, NE, USA
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