Sorption studies on regenerated cellulosic fibers in salt–alkali mixtures

Abstract

The degrees of salt sorption were determined in lyocell and viscose fibers immersed in aqueous solutions of salt-alkali mixtures with the aim of using salt sorption as an indirect measure of changes to fiber accessibility in presence of alkali. The salt-alkali mixtures used were combinations of NaOH with NaCl or NaBr, and of KOH with KCl or KBr. In general, salt sorption in fibers increased with increase in alkali concentration up to 2 mol/l, and did not change significantly thereafter. The accessibility of Br ) salts was greater than the Cl ) salts, but that of the Na + salts was greater than the K + salts. These trends in salt sorption indicate that salt accessibility in fibers is not influenced by the size of hydrated salt ions, but by the forces of electrostatic attraction and repulsion between the charged fiber surface and salt cations and anions.Nomenclature: [X] f -Alkali or salt sorbed by fiber (mol/g Fiber); [X] s -Alkali or salt content in treatment liquor (mol/l); [Y] f -Alkali or salt desorbed by fiber (mol/g fiber); [Y] s -Alkali or salt content in wash liquor (mol/l); CLY -Lyocell fibers without spin finish; CLY-sp -Lyocell fibers with spin finish CV -Viscose fibers; MC -Fractional moisture content of fibers; SRV -Solution retention value of fiber (ml/g); V -Volume of wash liquor (ml); W C -Weight of conditioned fibers; W D -Weight of dry fibers (g) W S -Weight of oven-dried fibers (g); W W -Weight of wet fibers (g); q -Density of treatment solution (g/ml)

Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin

“…Then the fibers were dried in room temperature followed by oven drying for 3 h at 105°C. Fiber behavior on alkali treatment was studied in previous research (Ramamoorthy et al 2014;Jaturapiree et al 2006;Okubayashi and Bechtold 2005).…”

“…Regenerated cellulose fibers are chemically pure, their surface structure is even, and the fiber properties can be reproduced easily (Woodings 2001;Carrillo et al 2010;Adusumali et al 2006;Fink et al 2014). It is also found that these fibers have good potential to be used as reinforcement in FRC (Carrillo et al 2010;Adusumali et al 2006;Ganster and Fink 2006;Jaturapiree et al 2006). High surface evenness and even quality of these fibers makes it possible to get consistent results which are not possible in natural fiber (Woodings 2001).…”

Attenuated total reflectance Fourier-transform Infrared spectroscopy analysis of crystallinity changes in lyocell following continuous treatment with sodium hydroxide

“…Treatment with alkali can improve mechanical and chemical properties of cellulose fibres such as dimensional stability, fibrillation tendency, tensile strength, dyeability, reactivity, lustre and fabric smoothness. Factors such as the concentration of NaOH, treatment temperature, applied tension, residence time, source of cellulose, physical state of cellulose (fibril, fibre, yarn or fabric), and degree of polymerisation have an effect on the properties and degree of change upon treatment (Heinze and Wagenknecht 1998;Colom and Carrillo 2002;Jaturapiree et al 2006;Manian et al 2008).…”

Dyeing behaviour of lyocell fabric: effect of NaOH pre-treatment

“…Treatment with alkali can improve mechanical and chemical properties of cellulose fibres such as dimensional stability, fibrillation tendency, dyeability, reactivity, lustre and fabric smoothness. Factors such as the concentration of NaOH, treatment temperature, applied tension, residence time, source of cellulose, physical state of cellulose (fibril, fibre, yarn or fabric), and degree of polymerisation have an effect on the properties and degree of change upon treatment (Heinze and Wagenknecht 1998;Colom and Carrillo 2002;Jaturapiree et al 2006;Manian et al 2008). In general, there is limited research in this area on cellulose II polymers; researchers have concluded that when cellulose I is converted to cellulose II the crystallinity index decreases, therefore, it is interesting to understand the change in crystallinity of cellulose II polymers when treated in alkali, particularly considering the increasing demand for lyocell fibres.…”