Comparing Mechanical Properties of Normal and Compression Wood in Norway Spruce: The Role of Lignin in Compression Parallel to the Grain

Holzforschung ◽  
2002 ◽  
Vol 56 (4) ◽  
pp. 395-401 ◽  
Author(s):  
W. Gindl
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cell Wall ◽  
Mechanical Testing ◽  
Cell Walls ◽  
Compression Wood ◽  
Lignin Content ◽  
Microfibril Angle ◽  
Compression Failure

Summary Cell-wall lignin content and composition, as well as microfibril angle of normal and compression wood samples were determined prior to mechanical testing in compression parallel to the grain. No effect of increased lignin content on the Young's modulus in compression wood was discernible because of the dominating influence of microfibril angle. In contrast, compressive strength of compression wood was not negatively affected by the high microfibril angle. It is proposed that the observed high lignification in compression wood increases the resistance of the cell walls to compression failure. An increased percentage of p-hydroxyphenylpropane units observed in compression wood lignin may also contribute to the comparably high compressive strength of compression wood.

Molecular xylem cell wall structure of an inclined Cycas micronesica stem, a tropical gymnosperm

IAWA Journal ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Clemens M. Altaner ◽  
Michael C. Jarvis ◽  
Jack B. Fisher ◽  
Thomas E. Marler
Keyword(s):  
Cell Wall ◽  
Compression Wood ◽  
Lignin Content ◽  
Microfibril Angle ◽  
Picea Sitchensis ◽  
Wall Structure ◽  
Crystalline Cellulose ◽  
Cellulose Structure ◽  
Molecular Features ◽  
Cellulose Fibrils

The molecular structure of tracheid walls of an inclined eccentrically grown stem of Cycas micronesica K.D. Hill did not differ between the upper and lower side. The absence the typical molecular features of compression wood tracheids, i.e. an increased galactose and lignin content as well as an increased microfibril angle, indicated that cycads do not have the ability to form even very mild forms of compression wood, which lacks anatomical features commonly observed in compression wood. Analysis of the sugar monomers in Cycas micronesica tracheids did reveal a rather unique composition of the non-cellulosic polysaccharides for a gymnosperm. The low mannose and high xylose content resembled a cell wall matrix common in angiosperms. The crystalline cellulose structure in Cycas micronesica tracheids closely resembled those of secondary cell walls in Picea sitchensis (Bong.) Carr. tracheids. However, the spacing between the sheets of cellulose chains was wider and the cellulose fibrils appeared to form larger aggregates than in Sitka spruce tracheids.

scholarly journals UDP-GLYCOSYLTRANSFERASE 72E3 Plays a Role in Lignification of Secondary Cell Walls in Arabidopsis

2020 ◽  
Vol 21 (17) ◽  
pp. 6094
Author(s):  
Fabien Baldacci-Cresp ◽  
Julien Le Roy ◽  
Brigitte Huss ◽  
Cédric Lion ◽  
Anne Créach ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Mutant Cell ◽  
Subsequent Investigation ◽  
Secondary Cell Walls ◽  
Chemical Determination ◽  
Safranin O

Lignin is present in plant secondary cell walls and is among the most abundant biological polymers on Earth. In this work we investigated the potential role of the UGT72E gene family in regulating lignification in Arabidopsis. Chemical determination of floral stem lignin contents in ugt72e1, ugt72e2, and ugt72e3 mutants revealed no significant differences compared to WT plants. In contrast, the use of a novel safranin O ratiometric imaging technique indicated a significant increase in the cell wall lignin content of both interfascicular fibers and xylem from young regions of ugt72e3 mutant floral stems. These results were globally confirmed in interfascicular fibers by Raman microspectroscopy. Subsequent investigation using a bioorthogonal triple labelling strategy suggested that the augmentation in lignification was associated with an increased capacity of mutant cell walls to incorporate H-, G-, and S-monolignol reporters. Expression analysis showed that this increase was associated with an up-regulation of LAC17 and PRX71, which play a key role in lignin polymerization. Altogether, these results suggest that UGT72E3 can influence the kinetics of lignin deposition by regulating monolignol flow to the cell wall as well as the potential of this compartment to incorporate monomers into the growing lignin polymer.

scholarly journals Comparative studies on the mechanical properties and microstructures of outerwood and corewood in Pinus radiata D. Don

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Ming-yue Li ◽  
Hai-qing Ren ◽  
Yu-rong Wang ◽  
Ying-chun Gong ◽  
Yong-dong Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cell Wall ◽  
Crystallite Size ◽  
Wall Thickness ◽  
Pinus Radiata ◽  
Microfibril Angle ◽  
Cell Wall Thickness ◽  
Modulus Of Rupture ◽  
Relative Crystallinity

AbstractTwenty-year-old Pinus radiata trees imported from New Zealand were investigated, and a comparison was made between the outerwood (rings 16–20) and corewood (rings 4–6) in terms of mechanical properties, anatomical characteristics, microfibril angle (MFA), relative crystallinity, crystallite size and lignin content to determine the relationship between their mechanical properties and microstructures. The results demonstrated that the mechanical properties of the Pinus radiata outerwood were significantly better than those of the corewood. The outerwood had a modulus of rupture (MOR) of 106 MPa, a modulus of elasticity (MOE) of 11.4 GPa, and compressive strength parallel to the grain of 38.7 MPa, and the MOR, MOE and compressive strength parallel to the grain of the corewood were 78.9 MPa, 7.12 GPa and 29.3 MPa, respectively. The observed microstructures of the Pinus radiata outerwood and corewood were different, mainly due to differences in cell wall thickness, MFA, and relative crystallinity. The double wall thickness of the tracheid cells of the corewood and outerwood were 3.65 and 5.02 µm, respectively. The MFA data indicated that the average MFA of the outerwood was 14.0°, which was smaller than that of the corewood (22.3°). With X-ray diffraction, the relative crystallinity of the corewood was determined to be 35.7%, while that of the outerwood was 40.2%. However, the crystallite size of the outerwood cell wall shows no obvious difference from that of the corewood. Imaging FTIR spectroscopy showed a slightly higher relative content of lignin in the cell wall of the outerwood. The correlation between the microstructures and mechanical properties showed that the corewood with a thin cell wall, large MFA and low relative crystallinity had poor mechanical properties, while the outerwood with a thicker tracheid, smaller MFA and higher relative crystallinity had better mechanical properties. This means that the MFA, relative crystallinity and cell wall thickness synergically affect the mechanical properties of Pinus radiata in different radial locations.

Evaluation of the effects of compression combined with heat treatment by nanoindentation (NI) of poplar cell walls

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 167-173 ◽  
Author(s):  
Xinzhou Wang ◽  
Yuhe Deng ◽  
Siqun Wang ◽  
Chen Min ◽  
Yujie Meng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Cellulose Crystallinity ◽  
Hot Press ◽  
Longitudinal Elastic Modulus ◽  
Modification Method ◽  
Compressed Wood

Abstract A combination of compression and heat treatment is a modification method that has great potential for improving the mechanical properties and dimensional stability of wood materials in industrial application. The objective of this project was to track changes in the microstructure, chemical composition, cellulose crystallinity, and mechanical properties of the treated poplar cell wall to investigate the mechanism of modification. Poplar boards were compressed at 100°C and subsequently treated in the hot press at 200°C. The results indicated that the treatment contributed to a reduction in porosity without obvious mechanical compression and damage to the cell wall. Hemicellulose degraded, however, and the relative lignin content and cellulose crystallinity increased during the process. The observed increase in relative lignin content and crystallinity may contribute to the improvement of mechanical properties. The longitudinal elastic modulus and hardness of poplar cell walls increased significantly from 12.5 and 0.39 GPa for the control to a maximum of 15.7 and 0.51 GPa for compressed wood with HT, respectively.

Microfiber Angle and its Effect on Wood Cell Behavior

2017 ◽  
Vol 1144 ◽  
pp. 88-93
Author(s):  
Vera Hlavata ◽  
Pavel Kuklik ◽  
Jiří Celler ◽  
Jan Vanerek
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Modulus Of Elasticity ◽  
Building Materials ◽  
Lignin Content ◽  
Strong Dependence ◽  
Complex Structure ◽  
Microfibril Angle ◽  
Cell Behavior ◽  
Main Task

The article continues the previous one “Coefficients of Transverse Contraction of the Wood Cell Constituents and their Effect on the Cell Behavior”. Wood, as being one of the most commonly used building materials, disposes of complex structure and basic building unit of a wood-cell. Each individual cell is composed of four distinct cell wall layers - the Primary, S1, S2, and S3. This work focuses on a closer examination of the relationship between microscopic and mechanical properties of wood. The main task was an effect of micro fibril angle (MFA) in the S2 layer of a wood on the cell wall parameters. This layer occupies more than 80% of the total thickness of the cell wall and thus has the greatest influence on the mechanical properties of wood cells. MFA values as well as values of bulk density has a strong dependence on the modulus of, elasticity in the longitudinal direction, as well as on the values of shrinkage. We tried to describe the dependence of the longitudinal modulus of elasticity on its. The proposed formula was partially validated using nanoindentation experiments performed in Norway spruce cell walls with highly variable cellulose microfibril angle and lignin content [5].

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

scholarly journals Study on Improving the Fixation Rate of Impregnated Poplar Wood with Maltodextrin and 1,3-Dimethylol-4,5-Dihydroxyethyleneurea

2019 ◽  
Vol 9 (16) ◽  
pp. 3237
Author(s):  
Mingzhen Cai ◽  
Zongying Fu ◽  
Yingchun Cai ◽  
Yue Zhang
Keyword(s):  
Compressive Strength ◽  
Cell Wall ◽  
Fourier Transform ◽  
Cell Walls ◽  
Poplar Wood ◽  
Fixation Rate ◽  
Practical Applications ◽  
Wall Materials ◽  
Impregnated Wood ◽  
Cell Wall Materials

The impregnation of poplar wood (Populus adenopoda Maxim) with 1,3-dimethylol-4,5-dihydroxyethyleneurea and maltodextrin and the effects of ZnCl2 and curing at 103 °C and 120 °C on the fixation rate and the leaching resistance of modified samples were investigated (103 °C curing, ZnCl2 + 103 °C curing, 120 °C curing, and ZnCl2 + 120 °C curing are denoted as 103, ZC-103, 120, and ZC-120, respectively), with the aim of improving the modification effect. The results showed that ZC-103 had the highest fixation rate, and its weight leaching ratio was higher than that of 120. Fourier-transform infrared spectroscopy showed that ZnCl2 did not affect the functional groups of the modified chemicals. The flexural strength and modulus and the compressive strength perpendicular to the grain were highest for ZC-103. In summary, ZC-103 exhibited the highest fixation rate, indicating that the hardener ZnCl2 bridged and increased the interfacial properties between the chemicals and cell walls and therefore increased the potential for macromolecule polycondensation between the chemicals and cell wall materials. This research paves the way for improving the fixation rate of impregnated wood and provides new insights into practical applications.

scholarly journals Characterization and Performance of Mechanical Properties of GGBS Based Geo Polymer Mortars

2019 ◽  
Vol 8 (4) ◽  
pp. 8336-8342
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Construction Industry ◽  
Research Paper ◽  
Setting Times ◽  
And Performance ◽  
Creep And Shrinkage

From decades it has been recognized that Geopolymer will considerably replace the role of cement in the construction industry. In general, Geopolymer exhibits the property of the peak compressive strength, minimal creep and shrinkage. In this current research paper, Geopolymer mortar is prepared by using GGBS and Fly ash. The mix proportions are of (100-60)%GGBS with Fly ash by 10% replacement. The alkali activators Na0H and Na2Sio3 are used in the study for two different molarities of 4&8. The ratio to Sodium silicates to sodium hydroxide is maintained from 1.5, 2, 2.5 & 3 were used. Mortars are prepared and studied the effect of molarities of alkali activators in their setting times and strengths

scholarly journals Hypolignification: A Decisive Factor in the Development of Hyperhydricity

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2625
Author(s):  
Nurashikin Kemat ◽  
Richard G. F. Visser ◽  
Frans A. Krens
Keyword(s):  
Cell Wall ◽  
Lignin Content ◽  
Coumaric Acid ◽  
Wild Type ◽  
Higher Plant ◽  
Gene Coding ◽  
Phenylpropanoid Biosynthesis ◽  
Total Lignin ◽  
Total Lignin Content

One of the characteristics of hyperhydric plants is the reduction of cell wall lignification (hypolignification), but how this is related to the observed abnormalities of hyperhydricity (HH), is still unclear. Lignin is hydrophobic, and we speculate that a reduction in lignin levels leads to more capillary action of the cell wall and consequently to more water in the apoplast. p-coumaric acid is the hydroxyl derivative of cinnamic acid and a precursor for lignin and flavonoids in higher plant. In the present study, we examined the role of lignin in the development of HH in Arabidopsis thaliana by checking the wild-types (Ler and Col-0) and mutants affected in phenylpropanoid biosynthesis, in the gene coding for cinnamate 4-hydroxylase, C4H (ref3-1 and ref3-3). Exogenously applied p-coumaric acid decreased the symptoms of HH in both wild-type and less-lignin mutants. Moreover, the results revealed that exogenously applied p-coumaric acid inhibited root growth and increased the total lignin content in both wild-type and less-lignin mutants. These effects appeared to diminish the symptoms of HH and suggest an important role for lignin in HH.

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