Multifilament Fibers Based on Dissolution of Cellulose in NaOH/Urea Aqueous Solution: Structure and Properties

Abstract

In the 21st century, science and technology have moved toward renewable raw materials and more environmentally friendly and sustainable resources and processes.[1] The Technology Road Map sponsored by the U.S. Department of Energy (DOE) has targeted to achieve 10 % of basic chemical building blocks arising from plant-derived renewable sources by 2020. [2] Cellulose is the most abundant renewable organic material and can be converted into cellulose derivatives (ethers and esters) and regenerated materials (fibers, films, food casings, membranes, and sponges, among others).[3] Moreover, numerous new functional materials of cellulose are being developed over a broad range of applications. [1a,4] It is noted that the traditional viscose route for producing regenerated cellulose fibers, films, and nonwoven fabrics still dominates the current processing route.[1a] The viscose route is technologically complex and requires additional facilities to treat the gaseous and aqueous waste emissions (end-of-pipe technology), which makes it a growing urgency to develop a new pathway to avoid the complicated current routes and hazardous byproducts. An more environmentally friendly process of cellulose-fiber spinning using a direct solvent system, N-methylmorpholine-N-oxide (NMMO), has been developed, leading to a new class of man-made cellulose fibers with the generic name of Lyocell.[5]Lyocell fibers show better performance qualities, but the Lyocell process suffers from 1) uncontrolled thermal stability of the system NMMO-cellulose-H 2 O (a runaway reaction),2) high evaporation costs (energy costs), and 3) high tendency of fibrillation of the Lyocell fiber. [3,5] Faced with the serious pollution produced by the viscose method in China, India, and other countries, we hope to realize a dream of producing regenerated cellulose materials using the new route by using low-cost chemical reagents and a simple wet-spinning process that yields essentially nontoxic byproducts. In previous work, we developed a novel solvent system for cellulose, that is, an NaOH/urea aqueous solution precooled to -12°C, in which the dissolution of cellulose could be achieved rapidly at ambient temperatures (below 20°C).[6] Interestingly, cellulose with a relatively high molecular weight could not be dissolved in the solvent without being precooled to -12°C or without urea being added. The addition of urea and the low temperature play an important role in the improvement of the cellulose dissolution, because low temperature creates a large inclusion complex associated with cellulose, NaOH, urea, and H 2 O clusters, which bring cellulose into aqueous solution, even at relatively high cellulose concentrations. Moreover, the cellulose dope could remain in a liquid state for a long time period at about 0 to 5°C. [7] It has motivated us to develop a more economical and environmentally friendly cellulose-fiber-fabrication process on an industrial scale in order to demonstrate the utility of this solvent system. Here, we present a first attempt to prepare the wet...

Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

“…The mixed liquid was frozen at -7 °C for 2 hours. In the pretreatment solution, the weight ratio of NaOH:urea:H2O was 7:12:81 (Cai et al 2007). After freezing, the mixed liquid was centrifuged at 5000 rpm for 10 min several times to remove the supernatant.…”

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

“…[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.…”

Bifunctional Regenerated Cellulose Membrane Containing TiO2 Nanoparticles for Absorption and Photocatalytic Decomposition

“…In addition, the RC film possesses porous structure and high absorption ability. This is one of the surface functionality with hydroxyl group (Cai et al 2007) leading to its important characteristics in water treatment system in order to absorb more pollutant and undergo photodegradation. On top of that, the organicinorganic hybrid cellulose nanocomposites have attracted researchers due to their outstanding properties to be applied widely in various fields including biomedicine, food packaging and water purification.…”