scholarly journals Influência do lenho de tração nas propriedades físicas da madeira de Eucalyptus sp.

2010 ◽  
Vol 1 (1) ◽  
pp. 6-11
Author(s):  
Thiago Campos Monteiro ◽  
Renato da Silva Vieira ◽  
José Tarcísio Lima ◽  
Edy Eime Pereira Baraúna ◽  
Duam Matosinhos de Carvalho ◽  
...  
Keyword(s):  
Tension Wood ◽  
Basic Density ◽  
Eucalyptus Camaldulensis ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
The Face ◽  
Eucalyptus Maculata ◽  
Shrinkage Coefficient

The reaction wood is formed in an attempt to remain upright tree in response to the action of forces such as winds, irregular crown or slope of the land that tend to incline it. In hardwoods, as in Eucalyptus, this type of wood is called tension wood and occurs in the region of the stem facing the face of force application. Indicative of the presence of this type of wood is the high shrinkage and basic density compared to normal wood. Once the basic density and shrinkage are parameters for determining the quality of the wood, this study aimed to evaluate the variation of basic density and shrinkage of opposite and tension wood along the radius in four species of Eucalyptus sp. Four tree species Eucalyptus camaldulensis, Eucalyptus maculata, Eucalyptus pilularis and Eucalyptus urophylla, with 32 years of age, were taken from an experimental planting of the Federal University of Lavras. Specimens were made to represent the diametrical variation of the opposite of tension wood in disks cut at the dbh. The results indicate that the properties of radial, tangential and volumetric shrinkage, coefficient of anisotropy and basic density did not differ statistically between the tensionand opposite wood.

scholarly journals QUALITY OF REACTION WOOD IN Eucalyptus TREES TILTED BY WIND FOR PULP PRODUCTION

CERNE ◽  
2017 ◽  
Vol 23 (3) ◽  
pp. 291-297
Author(s):  
Walter Torezani Neto Boschetti ◽  
Juarez Benigno Paes ◽  
Graziela Baptista Vidaurre ◽  
Marina Donária Chaves Arantes ◽  
João Gabriel Missia da Silva
Keyword(s):  
Chemical Composition ◽  
Chemical Constituents ◽  
Wood Quality ◽  
Basic Density ◽  
Kraft Pulping ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Holocellulose Content

ABSTRACT This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by wind action. It also aims to explain the pulping parameters resultant from the quality of the wood. The trees were grouped into four tilt ranges, ranging from 0 to 50º, and the basic density, chemical composition of the wood, and performance in kraft pulping were assessed. Normal and tension wood had similar basic densities; while for opposite wood, the density was lower, being responsible for a decrease in reaction wood density. The chemical composition of the wood was influenced by the presence of reaction wood in the stem. Tension and opposite wood showed lower levels of extractives and lignin and higher holocellulose content when compared to normal wood, with favorable wood quality for pulping. The increase in holocellulose content and the reduction of lignin and extractives content contributed positively to a more delignified pulp and reduction of the Kappa number. However, after cooking the reaction wood under the same conditions as those of normal wood, reaction wood pulping tends to have a lower screen yields. Due to differences in basic density and chemical constituents between opposite and normal wood, it is recommended not to designate the opposite wood as normal wood.

scholarly journals Viscoelastic properties of green wood across the grain measured by harmonic tests in the range 0–95°C: Hardwood vs. softwood and normal wood vs. reaction wood

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 548-557 ◽  
Author(s):  
Vincent Placet ◽  
Joëlle Passard ◽  
Patrick Perré
Keyword(s):  
Storage Modulus ◽  
Viscoelastic Properties ◽  
Tension Wood ◽  
Radial Direction ◽  
Lignin Content ◽  
Softening Temperature ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Wood Compression

Abstract The viscoelastic properties of wood have been investigated with a dynamic mechanical analyser specifically developed for wooden materials, the WAVET device. Measurements were carried out on four wood species in the temperature range 0–100°C at frequencies varying between 5 mHz and 10 Hz. Wood samples were tested under water-saturated conditions in the radial and tangential directions. As expected, the radial direction always revealed a higher storage modulus than the tangential direction. Great differences were also observed in the loss factor. The tanδ peak and internal friction were higher in the tangential than in the radial direction. This behaviour is attributed to the fact that anatomical elements act as a function of the direction. The viscoelastic behaviour of reaction wood differs from that of normal or opposite wood. Compression wood of spruce, which has a higher lignin content, is denser and stiffer in transverse directions than normal wood, and has a lower softening temperature (T g). In tension wood, the G-layer is weakly attached to the rest of the wall layers. This may explain why the storage modulus and softening temperature of tension wood are lower than those for opposite wood. We also demonstrate that the time-temperature equivalence fits only around the transition region, i.e., between T g and T g+30°C. Apart from these regions, the response of wood reflects the combined effects of all its constitutive polymers, so that the equivalence is no longer valid.

The nature of reaction wood. IV. Variations in cell wall organization of tension wood fibres

1955 ◽  
Vol 3 (2) ◽  
pp. 177 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Wall ◽  
Degree Of Crystallinity ◽  
Tropical Species ◽  
Normal Wood ◽  
Reaction Wood ◽  
Gelatinous Layer ◽  
Wood Fibres ◽  
Cell Wall Organization

The cell wall organization, the cell wall texture, and the degree of lignification of tension wood fibres have been investigated in a wide variety of temperate and tropical species. Following earlier work describing the cell wall structure of tension wood fibres, two additional types of cell wall organization have been observed. In one of these, the inner thick "gelatinous" layer which is typical of tension wood fibres exists in addition to the normal three-layered structure of the secondary wall; in the other only the outer layer of the secondary wall and the thick gelatinous layer are present. In all the tension wood examined the micellar orientation in the inner gelatinous layer has been shown to be nearly axial and the cellulose of this layer found to be in a highly crystalline state. A general argument is presented as to the meaning of differences in the degree, of crystallinity of cellulose. The high degree of crystallinity of cellulose in tension wood as compared with normal wood is attributed to a greater degree of lateral order in the crystalline regions of tension wood, whereas the paracrystalline phase is similar in both cases. The degree of lignification in tension wood fibres has been shown to be extremely variable. However, where the degree of tension wood development is marked as revealed by the thickness of the gelatinous layer the lack of lignification is also most marked. Severity of tension wood formation and lack of lignification have also been correlated with the incidence of irreversible collapse in tension wood. Such collapse can occur even when no whole fibres are present, e.g. in thin cross sections. Microscopic examination of collapsed samples of tension wood has led to the conclusion that the appearance of collapse in specimens containing tendon wood can often be attributed in part to excessive shrinkage associated with the development of fissures between cells, although true collapse does also occur. Possible explanations of the irreversible shrinkage and collapse of tension wood fibres are advanced.

Strength and stiffness of the reaction wood in five Eucalyptus species

Holzforschung ◽  
2019 ◽  
Vol 73 (2) ◽  
pp. 219-222
Author(s):  
Bruno Charles Dias Soares ◽  
José Tarcísio Lima ◽  
Selma Lopes Goulart ◽  
Claudineia Olímpia de Assis
Keyword(s):  
Mechanical Behavior ◽  
Tension Wood ◽  
Compression Wood ◽  
Vertical Position ◽  
Eucalyptus Species ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Average Slope ◽  
Strength And Stiffness

AbstractTree stems deviating from the vertical position react by the formation of tension wood (TW) or compression wood (CW), which are called in general as reaction wood (RW), in which the cells are modified chemically and anatomically. The focus of the present work is the mechanical behavior of TW in five 37-year-oldEucalyptusspecies, which were grown on a planting area with an average slope of 28% leading to decentralized pith in the trees, which is an unequivocal indication of the presence of RW. TW and opposite wood (OW) samples were isolated and subjected to a compression-parallel-to-grain test. It was observed that TW is less resistant and less stiff than the OW.

scholarly journals Structural differences between reaction wood and opposite wood with different drying temperatures

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 4407-4416
Author(s):  
Ivan Klement ◽  
Tatiana Vilkovská ◽  
Peter Vilkovský ◽  
Štěpán Hýsek
Keyword(s):  
Physical And Mechanical Properties ◽  
Thick Wall ◽  
Normal Wood ◽  
Reaction Wood ◽  
Drying Time ◽  
Fiber Cells ◽  
Opposite Wood ◽  
Negative Effect ◽  
Higher Temperature ◽  
End Times

Reaction wood is characterized by having different anatomical and chemical features than normal wood. The different composition of cell walls, the higher quantitative proportion of thick-wall fiber cells, diameter, and the abundance of vessels have remarkable effects on reaction wood’s physical and mechanical properties. Reaction wood has fewer vascular cells. In addition, it has a smaller lumen diameter, which results in reduced permeability. Therefore, reaction wood is more difficult to dry at a certain moisture content. The differences in the drying times of the reaction wood and the normal wood were largest at a temperature of 60 °C and durations greater than 30 h, and the reaction wood dried more slowly. At a temperature of 120 °C, the differences in drying time were minimalized, and drying end times were almost identical. The expected negative effect of higher temperature on the morphology of reaction wood and opposition wood was not confirmed.

Wood quality in artificially inclined 1-year-old trees of Eucalyptus regnans — differences in tension wood and opposite wood properties

2011 ◽  
Vol 41 (5) ◽  
pp. 930-937 ◽  
Author(s):  
Shakti S. Chauhan ◽  
John C.F. Walker
Keyword(s):  
Tension Wood ◽  
Wood Quality ◽  
Basic Density ◽  
Wood Properties ◽  
Acoustic Velocity ◽  
Volumetric Shrinkage ◽  
Longitudinal Shrinkage ◽  
Eucalyptus Regnans ◽  
New Approach ◽  
Opposite Wood

This paper presents a new approach to assess wood quality in 1-year-old Eucalyptus regnans F. Muell. Twenty-two seedlings were grown tilted to induce tension wood and acoustic velocity, basic density, longitudinal shrinkage, and volumetric shrinkage of both opposite wood and tension wood were assessed subsequently. Longitudinal growth strains were also estimated in the leaning stems by sawing along the length through the pith and measuring the bending of the two halves. The derived longitudinal growth strain, which varied from 708 to 2319 µε, was uncorrelated with stem and wood characteristics. Wood characteristics differed significantly between upper-side wood (predominantly tension wood) and lower-side wood (opposite wood). Tension wood was characterized by a higher acoustic velocity (high stiffness), basic density, and volumetric shrinkage compared with opposite wood. Tension wood also exhibited significant collapse and dimensional distortion such as twisting. Longitudinal shrinkage exhibited a significant negative relationship with acoustic velocity in opposite wood and a positive relationship with the basic density in tension wood. This new approach has potential in early selection of breeding material with superior normal wood properties from 1-year-old material by isolating the influence of tension wood. This approach can also be useful in understanding the variability in propensity of tension wood production in breeding populations.

WITHIN-TREE VARIATION IN ANATOMICAL PROPERTIES OF COMPRESSION WOOD IN RADIATA PINE

IAWA Journal ◽  
2004 ◽  
Vol 25 (3) ◽  
pp. 253-271 ◽  
Author(s):  
Lloyd A. Donaldson ◽  
Jenny Grace ◽  
Geoff M. Downes
Keyword(s):  
Wall Thickness ◽  
Compression Wood ◽  
Microfibril Angle ◽  
Basic Density ◽  
Radiata Pine ◽  
Lumen Diameter ◽  
Normal Wood ◽  
Lignin Distribution ◽  
Opposite Wood ◽  
Anatomical Properties

Two trees of radiata pine, one showing severe lean, the other growing almost vertically, were assessed for the presence and anatomical properties of compression wood, including anatomy, lignin distribution, microfibril angle, basic density, radial and tangential lumen diameter and cell wall thickness. Both trees contained significant amounts of compression wood although the severity and amount of compression wood was greater in the leaning tree. Changes in lignin distribution seem to be characteristic of the mildest forms of compression wood with reduced lignification of the middle lamella representing the earliest change observed from normal wood. An increase in microfibril angle was associated with both mild and severe compression wood although examples of severe compression wood with the same or smaller microfibril angles than opposite wood, or with very small microfibril angles, were found. When segregated into mild and severe compression wood the average difference in microfibril angle was 4° and 8° respectively compared with opposite wood. Within-ring distribution of microfibril angle was different in severe compression wood compared to opposite wood with higher angles in the latewood.Severe compression wood showed a 22% increase in basic density compared to mild compression wood and opposite wood. The increased density was accounted for in terms of a 26% increase in tracheid wall thickness throughout the growth ring, offset by a 9% increase in radial lumen diameter, slightly greater in the latewood. There were no significant changes in density or cell dimensions in mild compression wood compared with opposite wood.

Air permeability in longitudinal and radial directions of compression wood of Picea abies L. and tension wood of Fagus sylvatica L.

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Asghar Tarmian ◽  
Patrick Perré
Keyword(s):  
Picea Abies ◽  
Fagus Sylvatica ◽  
Tension Wood ◽  
Compression Wood ◽  
Air Permeability ◽  
Normal Wood ◽  
Reaction Wood ◽  
Anatomical Point ◽  
Bordered Pits ◽  
The Difference

Abstract The air permeability in longitudinal and radial directions of compression wood in spruce (Picea abies) and tension wood in beech (Fagus sylvatica) was compared with that of the corresponding normal wood. The primary aim of the present study was to explain why the reaction woods dry more slowly than the normal woods in the domain of free water. A number of boards conventionally dried to an average final moisture content of 12% were chosen to perform the measurements. Bordered pits on the radial walls of longitudinal tracheids in the compression and normal wood and intervessel or intervascular pits in the tension and normal wood were also examined. The reaction wood of both species is less permeable than the normal wood, both in longitudinal and radial directions. The difference in permeability was more pronounced between compression and normal wood of spruce, especially in longitudinal direction. From an anatomical point of view, this is likely related to some differences in anatomical characteristics affecting the airflow paths, such as the pit features. Such results can explain the difference in drying kinetics of the reaction and normal woods in the capillary regime of drying.

Comparison of basic density and longitudinal shrinkage in tension wood and opposite wood in young stems of Populus euramericana cv. Ghoy when subjected to a gravitational stimulus

2001 ◽  
Vol 31 (10) ◽  
pp. 1676-1683 ◽  
Author(s):  
B Jourez ◽  
A Riboux ◽  
A Leclercq
Keyword(s):  
Physical Properties ◽  
Tension Wood ◽  
Basic Density ◽  
Small Samples ◽  
Longitudinal Shrinkage ◽  
Wood Tissue ◽  
Populus Euramericana ◽  
Opposite Wood ◽  
Gelatinous Fibers ◽  
Poplar Cuttings

In a greenhouse, under controlled conditions, young shoots, taken from poplar cuttings (Populus euramericana (Dole) Guinier cv. Ghoy), were artificially bent to quantify the modifications of physical properties induced by a gravitational stimulus. At the end of the growing season, basic density and longitudinal shrinkage were measured on very small samples taken from pure tension wood tissue observed on the upper face of the inclined axis and compared with opposite wood tissue, free of gelatinous fibers, developed on the opposite lower face. In a second step, shoots bent at two different lean intensities were analyzed. In young poplar wood, gravitational stimulus was found to have a significant effect on physical properties. Relations between basic density and longitudinal shrinkage are different depending on the types of wood considered. Shrinkage appears more sensitive to lean intensity in the range considered here.

scholarly journals Transcriptomics and Proteomics Reveal the Cellulose and Pectin Metabolic Processes in the Tension Wood (Non-G-Layer) of Catalpa bungei

2020 ◽  
Vol 21 (5) ◽  
pp. 1686 ◽  
Author(s):  
Yao Xiao ◽  
Fei Yi ◽  
Juanjuan Ling ◽  
Zhi Wang ◽  
Kun Zhao ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Tension Wood ◽  
Wood Formation ◽  
Normal Wood ◽  
Pectin Degradation ◽  
Opposite Wood ◽  
Pectin Content ◽  
Polysaccharide Synthesis ◽  
Secondary Wall Deposition ◽  
Catalpa Bungei

Catalpa bungei is an economically important tree with high-quality wood and highly valuable to the study of wood formation. In this work, the xylem microstructure of C. bungei tension wood (TW) was observed, and we performed transcriptomics, proteomics and Raman spectroscopy of TW, opposite wood (OW) and normal wood (NW). The results showed that there was no obvious gelatinous layer (G-layer) in the TW of C. bungei and that the secondary wall deposition in the TW was reduced compared with that in the OW and NW. We found that most of the differentially expressed mRNAs and proteins were involved in carbohydrate polysaccharide synthesis. Raman spectroscopy results indicated that the cellulose and pectin content and pectin methylation in the TW were lower than those in the OW and NW, and many genes and proteins involved in the metabolic pathways of cellulose and pectin, such as galacturonosyltransferase (GAUT), polygalacturonase (PG), endoglucanase (CLE) and β-glucosidase (BGLU) genes, were significantly upregulated in TW. In addition, we found that the MYB2 transcription factor may regulate the pectin degradation genes PG1 and PG3, and ARF, ERF, SBP and MYB1 may be the key transcription factors regulating the synthesis and decomposition of cellulose. In contrast to previous studies on TW with a G-layer, our results revealed a change in metabolism in TW without a G-layer, and we inferred that the change in the pectin type, esterification and cellulose characteristics in the TW of C. bungei may contribute to high tensile stress. These results will enrich the understanding of the mechanism of TW formation.

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