Swelling and Dissolution of Cellulose Part 1: Free Floating Cotton and Wood Fibres in N‐Methylmorpholine‐N‐oxide–Water Mixtures

Abstract

Five modes describing the behaviour of cellulose fibres dipped in a chemical have been identified:In the case of the behaviour of wood and cotton cellulose fibres in N-methylmorpholine-N-oxide (NMMO) and water mixtures, four domains of water content have been identified. Below 17% of water up to monohydrate (13%), the fibres are disintegrated into rod-like fragments and dissolve (mode 1). In NMMO -water mixtures containing 19-24% water, the cellulose fibres exhibit a heterogeneous swelling by forming balloons (composed of dissolved cellulose holds inside a membrane) separated with non-swollen sections. The whole fibre will completely dissolve (mode 2) in four successive steps (growth of the balloons, burst of the balloons, dissolution of the non-swollen sections and finally dissolution of the membrane). With still greater water contents (25-30%), only the ballooning phenomenon is observed, with a partial dissolution inside the balloon (mode 3). Above 35% of water, the fibres swell homogeneously and are not dissolving (mode 4).

Factors affecting the hygroexpansion of paper

“…Whereas a high concentration of covalent bonds in the cross section of an oriented polymer leads to high stiffness, a high concentration of hydrogen bonds transverse to the polymer backbone leads to a high swelling capacity [34]. This is in line with the description of swelling as ''the transport of the swelling agent through a system of pores and channels, leading to some splitting of hydrogen bonds of the cellulose dense, but accessible (meaning most of the time amorphous) regions'' [60].…”

“…The crystallinity of cellulose appears in different orders, and even amorphous regions (without any order) exist [60,68]. The exact relative amount of crystalline and amorphous cellulose depends on the species [69].…”

“…Additionally, the swelling dynamics of cellulose depend on the applied solvents [45,79]. Moreover, it was observed that the swelling was non-uniform along the fibers and showed some ''ballooning'' for different solvents [60]. One explanation might be that when the fibrils in the secondary wall swell transversely, the primary wall bursts at distinct spots.…”

Deep Eutectic Solvent as a Media in Swelling and Dissolution of Oil Palm Trunk

“…Many studies have been carried out for the dissolution of cellulose and wood fibre in various types of solvents such as NaOH [7], N-methylmorpholine-Noxide (NMMO) [8], lithium chloride/urea/water [9] and ionic liquids [10][11][12][13]. The swelling process of cellulosic materials can improve the reactivity and accessibility of the cellulose.…”

“…This phenomenon can be used to introduce activation of the substrate [14]. Five different modes were proposed for wood and cotton fibre dissolution as a function of solvent quality by using an NMMO-water system with or without additives [8].…”