Inhomogeneities in the Chemical Structure of Hardwood Lignins

Holzforschung ◽  
2003 ◽  
Vol 57 (3) ◽  
pp. 255-265 ◽  
Author(s):  
H. Önnerud ◽  
G. Gellerstedt
Keyword(s):  
Secondary Wall ◽  
Lignin Content ◽  
Middle Lamella ◽  
Size Exclusion ◽  
Wall Material ◽  
Thermomechanical Pulp ◽  
Aryl Ether ◽  
Spruce Wood ◽  
Exclusion Chromatography ◽  
The Difference

Summary Bauer-McNett fractions of an aspen chemi-thermomechanical pulp showed a significant variation with respect to lignin content and sugar composition, and two of the fractions were found to be particularly rich in middle lamella and secondary wall material, respectively. The secondary wall lignin of aspen was found to contain larger amounts of non-condensed β-O-4 aryl ether structures than the middle lamella lignin and the difference was attributed to a larger amount of syringyl structures as revealed by thioacidolysis. Size exclusion chromatography of the thioacidolysis products from birch and spruce wood showed a larger part of lignin oligomers being present in the degraded spruce lignin. Moreover, birch lignin had a lower phenolic content than both aspen and spruce lignin. Thioacidolysis followed by Raney-nickel desulphuration was used for the analysis of hardwood lignin trimers.

Inhomogeneities in the Chemical Structure of Spruce Lignin

Holzforschung ◽  
2003 ◽  
Vol 57 (2) ◽  
pp. 165-170 ◽  
Author(s):  
H. Önnerud ◽  
G. Gellerstedt
Keyword(s):  
Chemical Structure ◽  
Kraft Pulp ◽  
Periodate Oxidation ◽  
Middle Lamella ◽  
Size Exclusion ◽  
Thermomechanical Pulp ◽  
Normal Wood ◽  
Mechanical Grinding ◽  
Spruce Wood ◽  
Exclusion Chromatography

Summary Thioacidolysis, periodate oxidation and size exclusion chromatography (SEC) were used for the analysis of spruce lignin samples. The standard thioacidolysis method was modified by including a pre-swelling of the lignocellulosic sample before the reaction, and this gave a higher yield of monomer products. Middle lamella and compression wood lignin was found to contain a larger amount of oligomers after thioacidolysis than normal wood lignin. Analysis by thioacidolysis of a thermomechanical pulp (TMP) revealed that approximately 10% of the β-O-4 structures in the lignin were cleaved due to the mechanical grinding effect. From kraft pulp, the mixture of thioacidolysis products contains a major fraction having a considerably larger molecular mass than the products from spruce wood and TMP. The structure of this material is still unknown.

The Effect of Varying Latewood Proportion on the Radial Distribution of Lignin Content in a Pine Stem

Holzforschung ◽  
2001 ◽  
Vol 55 (5) ◽  
pp. 455-458 ◽  
Author(s):  
W. Gindl
Keyword(s):  
Radial Distribution ◽  
Secondary Wall ◽  
Lignin Content ◽  
Middle Lamella ◽  
Individual Growth ◽  
Juvenile Growth ◽  
Growth Rings ◽  
Strong Negative Correlation ◽  
Compound Middle Lamella ◽  
The Difference

Summary The radial distribution of lignin content in a pine stem was compared to latewood proportion. With the exception of the innermost juvenile growth rings, a strong negative correlation was found. However, the cell-wall lignin content of low lignin growth rings was equal to that of high-lignin growth rings. Therefore, the difference in lignin content between individual growth rings was solely due to varying ratios of high-lignin compound middle lamella to low-lignin secondary wall in thin- and thick-walled tracheids.

Comparing Mechanical Properties of Secondary Wall and Cell Corner Middle Lamella in Spruce Wood

IAWA Journal ◽  
1997 ◽  
Vol 18 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Rupert Wimmer ◽  
Barry N. Lucas
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Secondary Wall ◽  
Young's Modulus ◽  
Middle Lamella ◽  
Axial Direction ◽  
High Variability ◽  
Spatially Resolved ◽  
Spruce Wood ◽  
Cell Corner

Mechanical characterizations of the S2 layers and the cell corner middle lamella in the axial direction were investigated in spruce wood, A mechanical properties microprobe capable of measuring hardness and Young's modulus on a spatially resolved basis similar to that of an electron beam microprobe was used. Hardness of the cell comer middle lamella was found to be almost as high as that of the secondary wall, but the Young's modulus of the cell corner middle lamella was 50% less than that of the S2' The S2 showed constant hardness over its range of Young's modulus, but the cell corner middle lamella exhibited a strong correlation (R2 = 0.55) between hardness and the Young's modulus. Further investigations are needed to directly combine chemical and micromechanical properties and also to investigate the mechanical effects of the high variability of cell corner middle lamella chemistry.

Biomechanical pulping of spruce wood chips with Streptomyces cyaneus CECT 3335 and handsheet characterization

Holzforschung ◽  
2005 ◽  
Vol 59 (2) ◽  
pp. 173-177 ◽  
Author(s):  
Manuel Hernández ◽  
M. Jesus Hernández-Coronado ◽  
M. Isabel Pérez ◽  
Esteban Revilla ◽  
Juan C. Villar ◽  
...  
Keyword(s):  
Lignin Content ◽  
Middle Lamella ◽  
Treated Wood ◽  
Strength Properties ◽  
Wood Chips ◽  
Fiber Network ◽  
Spruce Wood ◽  
Gradual Loss ◽  
Acid Soluble Lignin ◽  
Streptomyces Cyaneus

AbstractThe actinobacteriumStreptomyces cyaneusCECT 3335 was evaluated for its ability to delignify spruce wood chips (Picea abies) after 2 weeks of incubation prior to refiner mechanical pulping. Weight loss of the chips during the treatment ranged from 2% to 3%. Chemicalanalysis of the treated wood showed an increase in acid-soluble lignin content concomitant with a notable increase in the acid/aldehyde+ketone [AC/(AL+KE)] ratio of the lignin compared with the control. Structural alterations in wood cell walls were observed by optical and scanning microscopy using astra blue-safranin staining and cryosections stained with gold/palladium, respectively. A gradual loss of lignin from the lumen towards the middle lamella and incipient defiberization could be observed. The estimation of specific energy for the defibration and refining stages of treated pulp showed a 24% reduction in the energy required, largely due to a 30% saving in the defibration of chips. The analysis of handsheets obtained from treated pulp showed a notable improvement in some strength properties, such as breaking length, tear index and stretch. In addition, the high Gurley air resistance value indicates more packing of the voids of the fiber network. These results demonstrate for the first time the suitability ofStreptomyces cyaneusfor biomechanical pulping purposes.

The composition of the carbohydrates in the middle lamella and secondary wall of tracheids from black spruce wood

1983 ◽  
Vol 61 (3) ◽  
pp. 506-508 ◽  
Author(s):  
P. Whiting ◽  
D. A. I. Goring
Keyword(s):  
Secondary Wall ◽  
Black Spruce ◽  
Middle Lamella ◽  
Spruce Wood ◽  
Softwood Species

Carbohydrate analyses were performed on fractions of tissue from the middle lamella and secondary wall of black spruce tracheids. The concentrations of glucose and mannose were found to be smaller in the middle lamella than in the secondary wall while the concentrations of galactose, arabinose, and xylose were slightly larger in the middle lamella than in the secondary wall. The results obtained are compared with data available in the literature for other softwood species.

Modification of Spruce Lignans with Trametes hirsuta Laccase

Holzforschung ◽  
2002 ◽  
Vol 56 (6) ◽  
pp. 579-584 ◽  
Author(s):  
J. Buchert ◽  
A. Mustranta ◽  
T. Tamminen ◽  
P. Spetz ◽  
B. Holmbom
Keyword(s):  
Gas Chromatography ◽  
Size Exclusion Chromatography ◽  
Uv Spectroscopy ◽  
Size Exclusion ◽  
Trametes Hirsuta ◽  
Spruce Wood ◽  
Exclusion Chromatography

Summary The effect of Trametes hirsuta laccase on isolated spruce wood lignans was evaluated. Lignans were isolated from the heartwood of spruce branches and treated with different laccase dosages and treatment times. The effect of the treatment was monitored by gas chromatography, size exclusion chromatography and ionization difference UV spectroscopy. Lignans were efficiently oxidized by T. hirsuta laccase. About half of the phenolic groups present in lignans remained intact during the treatment. The oxidation of phenolic groups in lignans produced oligomeric structures containing approximately 4–5 lignan units (i.e., 8–10 phenyl propane units). Precipitation of the formed oligomeric structures probably prevented further polymerization.

The phenolic hydroxyl content of lignin in spruce wood

1980 ◽  
Vol 58 (23) ◽  
pp. 2411-2414 ◽  
Author(s):  
J.-M. Yang ◽  
D. A-I. Goring
Keyword(s):  
Secondary Wall ◽  
Black Spruce ◽  
Middle Lamella ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Content ◽  
Spruce Wood ◽  
Cell Corner ◽  
Ultraviolet Microscopy

Values of the phenolic hydroxyl content of the lignin in the secondary wall and cell corner middle lamella of the tracheids in black spruce wood were found by ultraviolet microscopy to be 0.12 and 0.06 PhOH/C9 respectively. The overall value for the lignin in black spruce wood was 0.10 PhOH/C9.

Improvement of kraft pulp bleaching by treatments with laccase, urea, and refining

Holzforschung ◽  
2013 ◽  
Vol 67 (6) ◽  
pp. 651-658 ◽  
Author(s):  
Xueyu Du ◽  
Maria E. Eugenio Martín ◽  
Jiebing Li
Keyword(s):  
Lignin Content ◽  
Size Exclusion ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Lignin Fraction ◽  
Nuclear Magnetic Resonance Spectra ◽  
Kraft Pulp Bleaching ◽  
Mediator System ◽  
Exclusion Chromatography ◽  
Hexenuronic Acid

Abstract Unbleached Eucalyptus kraft pulps were treated by three methods and the bleaching effects have been evaluated. The treatments were performed by a laccase-mediator system (LMS), refining (R), and urea (U) alone and in combination of these methods. The bleached pulps were characterized in terms of κ number, hexenuronic acid content, brightness, and viscosity. In addition, the lignin-carbohydrate complexes (LCCs) were fractionated and characterized with regard to the fractionation yield, lignin content, and carbohydrate composition. Moreover, the 1H nuclear magnetic resonance spectra were recorded and the thioacidolysis-gas chromatography and thioacidolysis-size exclusion chromatography analyses were performed. The LMS treatment resulted mainly in a slightly better delignification as manifested by a κ number (K no.) reduction of 0.8 units. The effects of the U treatment included delignification (1.4 κ units), hexenuronic acid removal (3 μmol g-1), and improved pulp brightness (3.4 ISO units). The R treatment darkened the pulp (3 ISO units), whereas the bleaching of the R-pulp by subsequent LMS or U treatment enhanced the brightness (0.5 unit more) or delignification (0.3 unit more). The residual lignin in the pulp samples was present mainly as xylan-lignin. The Klason lignin content from the xylan-lignin fraction decreased as the degree of delignification increased. The pulp darkening followed by the R treatment was interpreted as the result of the formation of condensed lignin structures, but these condensed lignins were substantially removed by the subsequent LMS or U treatment.

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