Showing papers on "N-Methylmorpholine N-oxide published in 2016"

Pretreatment of Lignocelluloses With Solvent N-Methylmorpholine N-oxide

Abstract: Three decades after N-methylmorpholine N-oxide (NMMO) was first introduced as a solvent for direct cellulose dissolution, the usage of NMMO in the fiber-making industry has flourished throughout the world. This success attracts the attention of researchers working in lignocellulosic biomass fractionation to use NMMO as an agent for lignocellulosic pretreatment in biofuel production. The present chapter presents the current status of NMMO for the pretreatment of lignocellulosic biomass for further fermentation to biofuels.

Phase-equilibrium and cellulose-coagulation kinetics for cellulose solutions in N-methylmorpholine-N-oxide

Abstract: The dissolution of cellulose in N-methylmorpholine-N-oxide monohydrate and the dissolution of N-methylmorpholine-N-oxide monohydrate in water have been studied via optical interferometry. A part of the phase diagram for the cellulose/N-methylmorpholine-N-oxide system has been constructed. The phase diagram is characterized by crystalline equilibrium, hysteresis of the melting temperatures of the solvents, and a region of anisotropy. Optical interferometry has been used for the first time to study the kinetics of cellulose coagulation during the interaction of cellulose solutions in N-methylmorpholine-N-oxide with water and water solutions of N-methylmorpholine-N-oxide. Information on the values of interdiffusion coefficients and the morphologies of the resulting cellulose films has been obtained. The possibility to use optical interferometry to analyze the interaction of a solution with the coagulating agent in the case of cellulose fiber and film formation has been demonstrated. The influences of temperature, the nature of the coagulating agent, and the cellulose content on the kinetics of the process and morphologies of the formed films have been shown. The use of N-methylmorpholine-N-oxide as a part of the coagulation system decreases the rate of interdiffusion of solutions, thereby resulting in a more uniform and dense morphology of cellulose films. Increased temperature causes diffusion acceleration, thereby leading to the formation of an anisotropic morphology of the cellulose films.

Rheological behavior and spinnability of ethylamine hydroxyethyl chitosan/cellulose co-solution in N-methylmorpholine-N-oxide system

Abstract: In this work, the novel chitosan derivative ethylamine hydroxyethyl chitosan (EHC) was synthesized and blended with cellulose in an aqueous N-methylmorpholine-N-oxide (NMMO) solution in order to fabricate antibacterial chitosan/cellulose fiber. The rheological behaviors of the obtained co-solution in both steady and dynamic states were carefully investigated to determine the spinnability of the co-solution. In steady state, the addition of EHC was found to preserve the power-law flow characteristics of cellulose in the aqueous NMMO solution, while broadening the first Newtonian fluid-flow area. Under dynamic conditions, both Han-plot and viscoelastic analyses indicated the homogeneity of the co-solution. EHC/cellulose antibacterial fibers were successfully spun via the lyocell process using aqueous NMMO as the solvent, confirming the excellent spinnability of the EHC/cellulose co-solution. Scanning electron microscopy was used to observe the morphology of the obtained EHC/cellulose fibers; they were also investigated for antibacterial activity. The obtained EHC/cellulose fiber exhibited good spinning consistency and strong antibacterial activity against Escherichia coli, demonstrating potential applications for the material in antibacterial textiles.

Optical microinterferometry method for evaluation of phase state and diffusion in ternary systems: phase separation in cellulose/N-Methylmorpholine-N-oxide/non-solvent mixtures

Abstract: Microinterferometry technique was used to evaluate the phase state and diffusion of cellulose solutions N-Methylmorpholine-N-oxide upon contact with non-solvents (water and aqueous solutions of isopropyl alcohol). The method was helpful in visualization of the structure of the forming cellulose film in connection with the diffusivity of the components of the systems. The interdiffusion coefficient were determined. Isopropyl alcohol addition to water slows down the diffusion of the coagulant into the cellulose solution thus delaying cellulose precipitation. Increase of temperature leads to formation of less dense cellulose film morphology with large vacuoles.