The solid-phase MMO process

Abstract

A scientific concept ~?[solid-t)hasephysicomechanical activation of cellulose with a direct solvent ~?fthe donor type, N-methvlmorpholine N-oxide (MMO), the basis oJ'new solid-phase MMO processing oJ'wood celhdose into the new cotton-likejibre Oreel | was elaborated. The high degree oJcrvstallinity and orientation ensure the high physicomechanical plvperties oJ'Orcel jibre.The unique properties of the initial wood cellulose as easily reproducible and biodegradable stock, elevated consumer characteristics of the fibres made from it, and increasing demand for these fibres due to population growth and an increase in demand for textiles ensure that a sufficiently stable volume of world cellulose fibre production will be maintained.The viscose process has been the basic industrial method for processing wood cellulose into fibres for the past century. However, the environmentally damaging viscose plants and the environmental protection standards stiffened in the '70s initiated the development of research to find a new, environmentally clean cellulose solvent. As a result of investigating a large number of solvent systems, dissolution of cellulose in a polar organic solvent of the donor type, N-methylmorpholine N-oxide (MMO), called the MMO process, was fornlulated as a real alternative to viscose production [1]. The process is environmentally clean because MMO is almost totally regenerated and does not foma products of decomposition.In addition to solving the environmental problem of processing cellulose into molded articles --fibres, filaments, films, etc., the MMO process is characterized by the important novelty of the technical solutions. In contrast to traditional viscose fibres, the new fibres acquired cotton-like properties. By decision of BISFA, the new fibres were given the general name of Lyocell. In the three decades since research in this direction began, MMO process technology has been developed, and the leading developer firms have begun production of Lyocell fibres with a total output of approximately 120,000 tons in 2000.The MMO process is a completely new type of cellulose fibre production technology. Cellulose is dissolved in MMO according to a direct mechanism, i.e., as a result of solvation processes of a physical nature alone. The other stages of the technology --spinning, coagulation, and drying --are also physical in nature.A three-phase diagram (Fig. 1) which can be used to follow the change in the phase composition of the three-component cellulose--MMO--H20 system during dissolution of cellulose is widely used by researchers for describing the features of the MMO process [2]. The first stage of the process --swelling of the cellulose in an aqueous solution of MMO --takes place in two stages. The first stage (C) is treatment of the cellulose with an aqueous solution of MMO until a homogeneous pulp containing, for example, 35% H20 , 9% cellulose, and 56% MMO, is formed. The second stage (B) consists of elimination of the excess water from the system and furmation of a homogeneous suspension of th...

The Effect of Alcohol Precipitants on Structural and Morphological Features and Thermal Properties of Lyocell Fibers

“…For fiber spinning, 16% cellulose solutions in NMMO were prepared based on the solid-state activation technique [36]. Sulfate pulp (Baikal Pulp and Paper Mill, Baykalsk, Russia) was preliminarily crushed and sieved in order to isolate a powder fraction with a particle size of up to 200 microns.…”

Membranes Based on Cellulose and Copolymers of Acrylonitrile Prepared from Joint Solutions

“…), but unfortunately, their practical application is limited due to either high cost, corrosive activity, difficulties of regeneration, or toxicity. The most promising solvent is N-methylmorpholine-N-oxide (NMMO), which is used in the so-called MMO process [ 6 ]. The production of cellulose fibers from solutions in NMMO reaches hundreds of thousands of tons, while films from these solutions are not produced on an industrial scale.…”

Lyocell fibre production using NMMO – A simulation-based techno-economic analysis

“…Recently, also other players in Asia and Turkey have initiated production and sales of Lyocell fibres. In search for sustainable alternatives for responding to the increasing need of textile fibres, other technologies using NMMO or other cellulose solvents have been developed (Golova et al 2000;Sayyed et al 2019;Makarov et al 2020). In addition, modifications to the two slightly differing original NMMO processes by Courtaulds Fibres and Lenzing have been proposed (Wendler et al 2012;Lidhure et al 2019).…”