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We have found that cellulose can be dissolved rapidly in the mixed solvent of tetrabutylammonium acetate (TBAA) and a polar aprotic solvents (PAS) at 50 °C and the obtained cellulose solution could be regenerated into cellulose film and fiber. The factors affecting the dissolution behavior of cellulose were investigated and it was found that the solubility and dissolution rate of cellulose in the mixed solvent are significantly dependent on the species of PAS and the molar ratio of PAS/TBAA. The suitable PAS are dimethyl sulfoxide, pyridine, dimethylacetamide, dimethylformamide and N-Methyl-2-pyrrolidone, and dimethyl sulfoxide is the best one in regard to the solubility and dissolution rate of cellulose. The optimal molar ratio of PAS/TBAA was determined by DN of the polar aprotic solvents. The dissolution behaviour of cellulose in the mixed solvent was proposed to involve the solvent diffusion, solvation of TBA

We have found that cellulose could be dissolved rapidly in the binary solvent of polar aprotic solvents (PAS) and tetrabutylammonium acetate (TBAA) in a high solubility. The polar aprotic solvents includes dimethyl sulfoxide, pyridine, dimethylacetamide, dimethylformamide and N-Methyl-2-pyrrolidone. The factors affecting the dissolution behavior of cellulose was investigated and it is indicated that the solubility and dissolution rate of cellulose in the binary solvent are significantly dependent on the species of PAS and the molar ratio of PAS/TBAA. Among all the polar aprotic solvents, dimethyl sulfoxide is the best one, being attributed to its high diffusivity and strong solvation ability. The optimal molar ratio of PAS/TBAA was determined by donor number of the polar aprotic solvents. The dissolution of cellulose in the binary solvent was proposed to involve three processes, namely solvent diffusion, solvation of TBAA as well as disruption of the intermolecular or intramolecular hydrogen bonds (H-bonds) of cellulose.

Spent chromated copper arsenate (CCA)-treated wood was liquefied in polyethylene glycol 400/glycerin (2:1w/w). Sulfuric acid (95–98%) and ferrous salts (FeSO4·7H2O or FeCl2·4H2O) were used as catalysts and additives, respectively. The resulting liquefied CCA-treated wood was diluted with aqueous solvents and was then mixed with complexion/precipitation agents, followed by precipitation or filtration to remove the toxic metal-bearing sediment. As a result, more than 90% of Cu, Cr or As was removed.

Cellobiose was used as a model compound to study the liquefaction mechanism of cellulose in the presence of phenol under acid catalysis. The reaction products of cellobiose were analyzed and isolated by high performance liquid chromatography (HPLC). About 17 dominant compounds were identified based on NMR, GC-MS and Mass analyses. Based on the structures and reaction behavior of the main products, a liquefaction pathway of cellulose was proposed

Summary By means of high performance liquid chromatography (HPLC) and gel permeation chromatography (GPC), the yields of the main reaction products and the polymeric portion formed in the reaction of guaiacylglycerol-β-guaiacyl ether (GG) under various acid-catalyzed conditions were quantified as a function of reaction time. Based on their forming sequence and reaction behavior, as well as their structural characteristics, an acid-catalyzed reaction mechanism of GG with phenol was proposed.

By means of gel permeation chromatography analysis, the molecular weights and molecular weight distributions of liquefied wood obtained under various liquefaction conditions and species of catalysts were investigated in order to trace the change in the structural characteristics of the liquefied wood. The results indicated that during the liquefaction reaction, wood components were subjected to decomposition, phenolation, and recondensation. The intensities of these reactions depended greatly on the reaction conditions and the species of catalysts, and their competing result determined the structural characteristics of the resulting liquefied wood. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 351–357, 1997

Guaiacylglycerol-β-guaiacyl ether (GG) was used as a starting material to study the liquefaction mechanism of lignin in the presence of phenol under elevated temperature without catalysts. The liquefaction products of GG obtained were analyzed by means of GPC and GC-MS. It was found that liquefaction of GG first produced relatively low molecular weight intermediates, followed by gradual conversion of these reaction intermediates to the polymeric products. After isolation by liquid chromatographic method, 28 main reaction intermediates were obtained and identified with the help of MS and NMR. It was found that they are mainly composed of guaiacol and various phenolated products of coniferyl alcohol, such as diphenylpropenes, phenylcoumaranes. phenylcoumarones and phenylflavanes. The detailed NMR data of these compounds and their assignments were demonstrated in this article.

A phenolated wood/phenol/formaldehyde cocondensed novolac-type resin was prepared with a two-stage procedure. Wood was first liquefied in the presence of phenol by using an acid catalyst to produce a phenolated wood, and after the liquefaction, formalin (i.e., formaldehyde aqueous solution) was added to conduct a cocondensation reaction for converting the remaining nonreacted phenol into resin components. It was found that this procedure can convert almost all the phenol remained after liquefaction into resin, and therefore significantly upgrades the practical value of the liquefaction technique. In addition, it can also greatly improve the thermofluidities of the phenolated wood resins and the mechanical properties of their molded products. As a result, the flow temperatures and melt viscosities of the cocondensed resins were much lower than those of the phenolated wood resins. However, these two properties were more or less similar to those of the conventional novolac resin, resulting in an excellent processability. The flexural properties of the molded products made from the cocondensed resins were much higher than those of the phenolated wood and also somewhat superior to those of the conventional novolac resin. Therefore, this preparation procedure is a prospective technique for preparing wood-based novolac resins. © 1995 John Wiley & Sons, Inc.

The liquefied wood resins obtained by liquefying wood in the presence of phenol using phosphoric acid as a catalyst were applied to prepare the moldings by using hexamine as a hardener. The effects of the molding conditions and the moldings' compositions on flexural properties and water-sorption kinetics of the moldings were investigated. It was found that the liquefied wood resins had satisfactory and almost uniform curing reactivity, although they were composed of different kinds of wood components. The flexural properties of the liquefied wood moldings were enhanced with an increase in the amount of combined phenol within the liquefied wood and became comparable to those of the commercial novolak when the amounts of combined phenol were larger than 75%. Furthermore, it was also found that with an increase in the content of wood fillers the flexural properties of the liquefied wood moldings were enhanced more effectively than were the cases of the commercial novolak moldings, exhibiting that the liquefied wood resins could gain a greater reinforced effect from compounding with the wood fillers than did the commercial novolak resins, and the greater the amount of combined phenol, the higher the reinforcing performance of wood fillers. In addition, water-sorption measurements and the SEM observations of the moldings indicated that the liquefied wood resins had much greater hydrophilicity than that of the novolak and revealed a greater compatibility with wood fillers. © 1995 John Wiley & Sons, Inc.

The liquefaction of wood in the presence of phenol using phosphoric acid as a catalyst and the flow properties of the obtained liquefied wood were investigated. It was found that phosphoric acid is a satisfactory catalyst for liquefying wood. The amount of phenol that reacts with the liquefied wood components (i.e., combined phenol) increases with an increase in liquefaction temperature, liquefaction time, catalyst content, or liquid ratio. By removing the free phenol, the resulting liquefied woods become novolaclike resins. The measurements of the flow properties of these liquefied woods reveal that the melts of liquefied woods behave as pseudoplastics and their flows obey the Ostwald de Waele power law equation. The amount of combined phenol within the liquefied wood and the presence of filler in the liquefied wood have great influence on their flow properties. The flowing temperature, activation energy, and zero shear viscosity of the liquefied woods show tendencies to increase with an increase in combined phenol. © 1994 John Wiley & Sons, Inc.

A mixed solvent of 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and dimethylacetamide (DMAc) was developed for various applications involving cellulose. By changing the ratio of DMAc, the mixed solvent could be used either for cellulose swelling (more than 65% DMAc), selective dissolution of the non-crystalline domains for extraction of the crystalline nanofibers of cellulose (35–60% DMAc), or complete dissolution (less than 30% DMAc). In the region of complete dissolution, the dissolution rate of cellulose increased drastically as the DMAc ratio increased. The cellulose nanofibers prepared in the mixed solvent of [bmim]Cl–DMAc (50% DMAc) had a diameter of 30 nm and maintained the crystalline structure of cellulose I. A model was proposed to describe the selective dissolution and fibrillation of cellulose nanofibers in the mixed solvent of [bmim]Cl–DMAc.