Solubility of Cellulose in NaOH/Urea Aqueous Solution

Abstract

ABSTRACT:NaOH/urea aqueous solution as solvent of cellulose including cotton linter, bagasse, alkali-soluble cellulose and Bemliese'" was studied by solubility analysis, viscometry and light scattering. The addition of 2-4 wt% urea significantly improved the solubility of cellulose in 6-8 wt% Na OH aqueous solutions, and moderate urea plays a role in improving solubility and avoiding the formation of cellulose gel. Celluloses I with viscosity-average molecular weight (M ry) of 6. 7 X 10 4 were completely dissolved in 6 wt% NaOH/4 wt% urea aqueous solution. Cellulose dissolved in 6 wt% N aOH/4 wt% urea aqueous solution degraded slowly with storage time, and M ry of cellulose in the solution decreased 20% after storage for 100 days. The stability of cellulose solution was higher than cellulose cuoxam. A regenerated cellulose membrane having the tensile strength of 88. 7 MPa and breaking elongation of 11 % was successfully prepared by coagulating 4 wt% Bemliese" solution in 6 wt% NaOH/4 wt% urea with 5 wt% CaCl 2 then 1.3 wt% HCl aqueous solution as coagulate at 20°C.KEY WORDS NaOH I Urea Aqueous Solution/ Solubility/ Viscosity/ Stability of Cellulose/ Regenerated Cellulose Membrane I Polymers from renewable resources attract much attention due to biodegradability and potential as substitute for petrochemicals in some fields. Plant cellulose is the richest natural polymer on the earth. Making use of cellulose to produce various products cannot only protect the environment from pollution, but save limited petroleum resources. 1 However, the molecular structure of cellulose, (3-( 1---+4)-D-glucan, allows chain-packing by strong inter-and intramolecular hydrogen-bonding, which interferes with efforts to process or modify the material. 2 Therefore, cellulose still has not reached its potential in many areas for all its availability. The most general solvents for dissolving cellulose are unsuitable.It is worth noting that in the viscose industry, pollution control places ever increasing restraint on the process. 3 The development of non-polluting process based on organic and inorganic solvents of cellulose is of great scientific or practical interest, and much attention should be given to such solvents as ammonia/ammonium thiocyanate,4·5 calcium-and sodium thiocyanate, 6 · 7 zinc chloride,s-io lithium chloride/dimethylacetamide, 2 · •12 Nmethylmorpholine-N-oxide13-15 and aqueous solution of sodium hydroxide. •17 N-methylmorpholine-N-oxide has been recognized as a direct cellulose solvent, but commercial facility producing cellosic fibers via this solvent has developed very slowly due to high cost and high spinning temperature. 1 s 7-9 wt% NaOH aqueous solution is one of the cheapest cellulose solvents, in which cellulose can be dissolved near 4 °C, since intermolecular hydrogen bonds are destroyed. 16 · 19 However, only from cellulose of relatively low molecular weight is impossible to obtain fibers, and cellulose with polymerization of over 250 is unstable_ is Kamide, Okajima, and coworkers 16 • 17 · 20 -22 report that...

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

“…A rather strong input to this hydrate hypothesis has come from Zhang's group where the NaOH or LiOH hydrates (even when urea is present) are said to destroy the inter-and intra-hydrogen bonds between cellulose molecules while the urea hydrates are believed to work as donors and receptors of hydrogen bonds between solvent molecules, thus preventing cellulose aggregation and leading to molecular dissolution of cellulose. [13][14][15][83][84][85][86][87] Solubility and miscibility are, in almost all cases, due to entropy of mixing and cellulose should not constitute an exception. 59 The solubility of a polymer is generally low because of a low translational entropy.…”

“…[11][12][13][14][15][16] Lithium salts are also worth mentioning due to their relevance for the analysis of cellulose and preparation of a wide variety of Regarding interactions that limit cellulose solubility in water and are responsible for cellulose aggregation, much focus has been on hydrogen bonds. This is in striking contrast to discussions about interactions of other polysaccharide systems.…”

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

“…There are other known routes for cellulose dissolution with inorganic complexes (Miyamoto et al 1995;Saalwächter et al 2000), or certain exotic organic solvents (Philipp 1993), which, however, cannot be considered sustainable for large scale production. In the early 1990s, alkali-based aqueous solvents started to gain more academic and technical attention for the reasons of being more environmental benign than other protocols (Isogai and Atalla 1998;Kamide et al 1992;Zhou and Zhang 2000). Especially the later research on cold sodium hydroxide-urea or thiourea solutions broke the threshold of dissolving cellulose of higher molecular weights (Cai et al 2008;Zhang et al 2002;Zhou and Zhang 2000).…”

“…In the early 1990s, alkali-based aqueous solvents started to gain more academic and technical attention for the reasons of being more environmental benign than other protocols (Isogai and Atalla 1998;Kamide et al 1992;Zhou and Zhang 2000). Especially the later research on cold sodium hydroxide-urea or thiourea solutions broke the threshold of dissolving cellulose of higher molecular weights (Cai et al 2008;Zhang et al 2002;Zhou and Zhang 2000). Cellulose can also be dissolved in phosphorous acid and some other strong acids, but usually depolymerization of the cellulose chains takes place markedly more rapidly than in alkaline solutions (Hao et al 2015;Medronho and Lindman 2014).…”

Synthesis and Characterization of Hydrogels based on Graft Copolymerization of Acrylamide on Chitin resulted from Enzymatic Isolation of Shrimp Waste

“…Namun, terdapat beberapa penelitian mengenai pelarutan kitin. Zhou et al, (2000) dan Hu et al, (2007) berhasil melarutkan kitin dalam pelarut campuran NaOH/Urea (8%/4%). (Lestari dkk) Hidrogel akrilamida banyak digunakan dalam bidang kesehatan dan agrikultur sebagai control erosi pada tanah, sebagai media bioaktif dalam pengolahan tanah serta sumber nitrogen dan karbon untuk tanaman (Xiao, 2001) (Erizal, 2011).…”