N-Methylmorpholine N-oxide

About: N-Methylmorpholine N-oxide is a research topic. Over the lifetime, 187 publications have been published within this topic receiving 5251 citations. The topic is also known as: N-Methylmorpholine oxide & N-Methylmorpholine 4-oxide.

Cellulosic aerogels as ultra-lightweight materials. Part 2: Synthesis and properties.

Abstract: Ultra-lightweight cellulose aerogels can be obtained inthree steps: (1) preparation of a cellulose solution inmolten N -methylmorpholine- N -oxide monohydrate(NMMOOH 2 O) at 110–1208C and casting of the viscousmass into moulds; (2) extraction of the solidified castingswith ethanol to initiate cellulose aggregation and toremove NMMOOH 2 O so that the fragile, fine-porous tex-ture of cellulose II is largely retained; and (3) drying ofthe lyogel using supercritical carbon dioxide (scCO 2 ).According to this approach, cellulosic aerogels were pre-pared from eight commercial cellulosic materials andpulps and analysed for selected chemical, physicochem-ical and mechanical parameters. The results reveal thatall aerogels obtained from 3% cellulose containingNMMOOH 2 O melts had a largely uniform mesoporousstructure with an average pore size of ;9–12 nm, sur-face area of 190–310 m 2 g -1 , and specific density of0.046–0.069 g cm -3 , but rather low mechanical stabilityexpressed as compressive yield strain of 2.9–5.5%. Allsamples showed viscoelastic behaviour, with Young’smodulus ranging from ;5to10Nmm

Lyocell fibres based on direct dissolution of cellulose in N-methylmorpholine N-oxide: Development and prospects

Abstract: The scientific principles of direct dissolution of cellulose in the NMMO—water system demonstrate the major possibility of obtaining concentrated spinning solutions and spinning hydrated cellulose fibres from them. The specific features of the properties of NMMO (high boiling point and insufficient thermal stability) that dissolves the NMMO—water system (narrow concentration range, optimum for dissolution of cellulose) makes it necessary to recycle the washing water by evaporating it, which causes high power consumption for this process. It is expedient to examine the possibilities of membrane technologies, including electrodialysis, for solving problems of recycling the solvent and cutting power consumption. However, this path only allows partially concentrating used washing water, since there is the danger of crystallization of NMMO di-and monohydrate. Spinning through an air gap from highly viscous solutions with long relaxation times at high spinneret draw ratios results in highly oriented fibres with high tensile rigidity (high deformation modulus). Fabrication of fibres whose properties correspond to ordinary viscose fibres will perhaps require “going away” from highly viscous solutions to a lower concentration and spinning by the ordinary wet method, but the volume of solvent used increases significantly, recycling it is more difficult, and power consumption increases. For the same reason of high orientation, the fibres exhibit important fibrillation when wet, and a “peach skin” effect is formed in the finished textiles. To reduce fibrillation, special treatments of the fabrics must be used, biofinishing, for example. During use of the articles, fibrillation can reappear, in laundering, for example. The technology for fabricating fibres of the Lyocell type requires solving many problems. Developing research on selecting alternative solvents and dissolving systems for direct dissolution of cellulose to obtain concentrated spinning solutions is simultaneously useful.