摘要:

Amorphous (noncrystalline) cellulose was prepared by dissolving cotton hydrocellulose in the dimethylsulfoxlde-paraformalde-hyde solvent system and regenerating the cellulose by slow addition of the resultant raethylol cellulose solution to stirred 0.2M sodium alkoxide in methanol :2-propanol (1:1 vol.). The regenerated celluloses, essentially devoid of residual methylol substic-uents (ca. 0.002 ra.s.), had x-ray diffractograras, Raman spectra, and solid-state13C-n.m.r. spectra characteristic of amorphous cellulose. In addition, 98–100% of the cellulose hydroxyl groups were accessible to proton exchange with deuterium oxide. For small scale (< 2 g) preparations, the d.p. and end group composition of the cellulose were essentially unaltered by the regeneration process.

ISSN:0277-3813    

DOI:10.1080/02773818608085213

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Furfuryl alcohol (FA) in aqueous medium at pH 2.0 and 90°C in presence of H2O2/Fe2polymerized under crosslinking, without grafting to cellulosic fibers if present. Under the same conditions acid-prepolymerized furfuryl alcohol (PFA) transformed into a water-soluble polymer that grafted to cellulosic fibers (polymer load of 68%) with a negligible formation of a crosslinked homo-polymer. Decrease in the reaction temperature or increase in the volume of water decreased the polymer load and grafting efficiency. Increases in the concentrations of H2O2, of Fe2+, of both, or of pH resulted in curves exhibiting maxima in grafting efficiency and polymer load. This was explained by the presence of second and first order members in the equation for the reaction rate of the formation of grafting active centers on PFA or cellulose. Increase in cellulose consistency decreased the polymer load but influenced the grafting efficiency to a secondary extent only, suggesting that activation of PFA rather than that of cellulose is responsible for grafting. Pretreatment of cellulose with H2O2/Fe2+before addition of PFA resulted in no grafting. Pretreatment of PFA before addition of cellulose gave a polymer load amounting to about 401 of what would have been expected if both reaction partners had been reacted simultaneously. This was explained by formation of time-stable active centers on PFA and of time-unstable active centers on PFA or cellulose.

ISSN:0277-3813    

DOI:10.1080/02773818608085214

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Bleached high-yield pulps undergo a much higher rate of light-induced brightness reversion than their chemical counterparts. This tendency to discolor is one of the main factors limiting the application of high-yield pulps to short-term products such as newsprint, tissue, toweling, and foodboard.

ISSN:0277-3813    

DOI:10.1080/02773818608085215

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Threo and erythro isomers of 3-acetoxy-1-(4-acetoxy-3-methoxyphenyl) -1- (9,10-dihydro-10-hydroxy-9-oxoanthracen-10-yl) -2-(2-tnethoxyphenoxy)-propane 8 have been synthesized. These compounds are appropriate model compounds for adducts between anthranol (9-hydroxyanthracene) and quinone raethides of β-aryl ether units in the lignin polymer. Adducts of this type are believed to result from side reactions during the anthraquinone-accelerated pulping of wood and may contribute to extensive losses of anthraquinone from the pulping system. The13C NMR chemical shift3 of C-10 in the threo and erythro isomers of β are 44.1 and 47.5 ppm relative to tetramethylsilane. Peaks with corresponding chemical shifts appeared in a spectrum of an acetylated adduct prepared from lignin and 9,10-3C labelled anthranol. As in model systems the threo isomer predominated.

ISSN:0277-3813    

DOI:10.1080/02773818608085216

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The heterogeneous reactions of fatty acid ketene dimer with methyl α-D-glucopyranoside, maltose, cellobiose, microcrystalline cellulose and a bleached kraft pulp have been investigated under base catalyzed conditions in N,N-dimethylformamide (DMF). The reaction products have been examined by13C-NMR and/or infrared spectroscopy. The spectral data provide the first direct evidence for β-ketoester formation with these substrates.

ISSN:0277-3813    

DOI:10.1080/02773818608085217

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The acetone soluble lignins of Pinus radiata wood, which had been steam exploded by the Australian Siropulper process, both with and without SO2pretreatment, have been examined by13C NMR spectroscopy. The marked structural effects of SO2pretreatment are discussed. A brief comparison of the lignins from wood treated by the Siropulper and Canadian Iotech processes (without SO2pretreatment) is also presented.

ISSN:0277-3813    

DOI:10.1080/02773818608085218

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hybrid poplar chips (6.35 mm square cross section) are converted to a 45–50 per cent mass yield of acetone soluble products when heated fairly rapidly to 330°C in the presence of water. Virtually no char or unconverted wood is produced at 330°C. Water (15%), carbon dioxide (6.4%), aqueous organics (8.5%), and carbon monoxide (0.4%) are also significant products. Element balances for carbon, hydrogen and oxygen are 86, 98 and 96%, respectively, based on total input, or 86, 80 and 75% based on the wood input.

ISSN:0277-3813    

DOI:10.1080/02773818608085219

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0277-3813    

DOI:10.1080/02773818608085212

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor