摘要:

The action of xylanases on chemical weed pulps was studied in the presence of a 1 mM HgCl2solution. In that medium, the encc-cellulases present in the crude enzyme mixture from the Easidicmycete Sporotrichum dimorphosporum were inhibited as shown by soluble sugar analysis end by Molecular weight determination of the carbanilated derivatives of the enzyme-treated pulps. After enzymatic hydrolysis, although the mass loss was less than2%of the dry material weight, important structural modifications were revealed by physical property determinations on the residual pulps. The water retention value which increases by20%, the mean pore radius which is reduced by a factor of 10, the scanning electron microscopic photographs which show fiber flexibility and external fibrillation and the molecular weight distribution curves, allow us to come to the conclusion that xylans are actually hydrolyzed in the whole delignified cell walls. Therefore, because of the xylan distribution with regard to cellulose microfibrils, the selective hydrolysis by xylanases might affect the cell wall cohesion and, thus, influence the papermaking properties of pulps.

ISSN:0277-3813    

DOI:10.1080/02773818608085221

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Two chemical bleached pulps were treated with a crude enzyme mixture in the presence of HgCI2, (1 mM). Such treatment inhibited endo-cellulases. Xylans were- thus subjected to selective in-situ hydrolysis. The enzyme-treated pulps car. be compared to slightly beaten pulps. The modified fibers show external fibrillation and reveal strong beatability. Therefore, a decrease in energy demand can be gained in the papermaking process.

ISSN:0277-3813    

DOI:10.1080/02773818608085222

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The chemical bonding of polysaccharides to the residual lignin remaining in bleachable grade loblolly pine (Pinus taeda) kraft pulp was examined by methylation analysis. Before analysis, most of the nonbonded polysaccharides were enzymatically hydrolyzed and the sugars were washed from the remaining solid to give a residual lignin that contained about 8% carbohydrates. The analysis indicated that the majority of the remaining sugars were present as oligomeric segments of well-characterized pulp polysaccharides. About one monomeric unit per oligomer was bonded to lignin.

ISSN:0277-3813    

DOI:10.1080/02773818608085223

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

High yields of D-glucose and D-xylese water soluble oligosaccharides were obtained by extraction of birch wood with anhydrous hydrogen fluoride at sub-ambient or ambient temperature. A small amount of carbohydrates remained in the resulting insoluble lignin. Investigation b) infrared spectroscopy as well as phenolic group analyses indicated a probable low level of aryl alkyl ether linkage cleavage, at least in the range of the reaction conditions studied. Alkaline nitrobenzene oxidation of lignin showed that, condensation occurred, as measured by the decrease in yield of total p-hydro-xybenzaldehydes, during the hydrogen fluoride treatment.

ISSN:0277-3813    

DOI:10.1080/02773818608085224

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Data are reported for the chemical analysis of the solid residues of supercritical extraction of Populus tremoloïdes in methanol. The lignin content is determined by the thioglycolic acid test as the Klason test is shown to yield an estimation of recondensed material in addition to lignin. The TFA acid hydrolyzates of SCE solid residues were analysed for simple sugars by HPLC. The results indicate that hydrolyzable material contains products of thermal degradation of polysaccharides.

ISSN:0277-3813    

DOI:10.1080/02773818608085225

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Solid state13C CP/MAS nuclear magnetic resonance spectra were obtained for unbleached kraft pulps prepared from white spruce with yields ranging from 47.6 to 96.1%. The observed trends of the relative peak intensities were found to correspond to established facts on kraft kinetics. These results suggest that13C CP/MAS NMR of wood and pulp could be used to study kinetics in situ.

ISSN:0277-3813    

DOI:10.1080/02773818608085226

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Bleached kraft softwood pulp was sequentially oxidized with ruthenium tetroxide, peroxidized with hydrogen peroxide and then grafted with acrylamide or acrylonitrile monomers in the presence of ferrous ions. Good polymer loadings and grafting efficiencies were obtained. It was found that hot pressed dry paper sheet properties could be improved by a small addition of polyacrylamide-grafted pulp.

ISSN:0277-3813    

DOI:10.1080/02773818608085227

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Southern pine, Douglas-fir, and aspen wood flakes were acetylated with acetic anhydride vapor and compared with flakes acetylated with liquid acetic anhydride diluted with xylene. The rate of acetylation was much lower for the vapor than for the liquid phase reaction. Acetylation weight percent gains above 20 were achieved by both methods. Flakeboards made from both types of flakes absorbed much less water, both in water soaking tests and when subjected to humid air, and swelled at a lower rate and to a lower extent than did control boards. At low weight gains of vapor phase acetylation, the rate and extent of swelling were higher than those found for the controls.

ISSN:0277-3813    

DOI:10.1080/02773818608085228

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:10.1080/02773818608085220

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor