scholarly journals Influence of Lignin On Plastic Flow Deformation of Wood

2021 ◽  
Author(s):  
Masako Seki ◽  
Mitsuru Abe ◽  
Tsunehisa Miki ◽  
Masakazu Nishida
Keyword(s):  
Physicochemical Properties ◽  
Plastic Flow ◽  
Middle Lamella ◽  
Untreated Wood ◽  
Low Energy ◽  
Compound Middle Lamella ◽  
Early Stages ◽  
Cell Structures ◽  
Initial Resistance ◽  
Flow Deformation

Abstract In this study, we clarified the influence of lignin in wood on its plastic flow deformation due to shear sliding of wood cells. Wood samples were subjected to delignification, where the lignin structure gradually changed, and characterized for their chemical and physicochemical properties, and deformability by free compression testing. The delignified wood deformed by efficient stretching and maintained its cell structures at a lower pressure compared to the untreated wood. The deformability was evaluated from two viewpoints: the initial resistance to plastic flow and final stretchability. The deformability of the delignified and untreated wood increased with increasing compressive temperature, even though the changes in molecular motility associated with the glass transition of lignin contributed minimally to the improvement in deformability. In the early stages of delignification, the molecular mass of lignin in the compound middle lamella decreased, which reduced the initial resistance to plastic flow. However, during the early stages of delignification, the stretchability of delignified wood was scarcely affected by changes in lignin. As the amount of lignin was further reduced and delignification proceeded in the vicinity of the polysaccharides, the stretchability significantly improved. The correlation between chemical and physicochemical properties and plastic flow deformability presented in this paper will be helpful for low-energy and highly productive forming of solid-state wood.

scholarly journals Flow deformation characteristics of African blackwood, Dalbergia melanoxylon

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Kazushi Nakai ◽  
Soichi Tanaka ◽  
Kozo Kanayama ◽  
Tsuyoshi Yoshimura
Keyword(s):  
Plastic Flow ◽  
Local Community ◽  
Tangential Direction ◽  
Musical Instruments ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Flow Forming ◽  
Community Forests ◽  
Flow Deformation ◽  
Dalbergia Melanoxylon

Abstract African blackwood (ABW: Dalbergia melanoxylon) is a valuable tree in Tanzanian local community forests, and heartwood has been mainly utilized as an irreplaceable material in musical instruments, e.g., clarinet, oboe and piccolo. Since its use is generally for the production of musical instruments only, most of the harvested volume is wasted due to defects that would affect the quality of final products. Wood flow forming can transform bulk woods into materials in temperature/pressure-controlled mold via plastic flow deformation. The main object of this study was to evaluate the deformation characteristics of ABW heartwood in developing the potential of wasted ABW parts in terms of the effective material use. The deformation characteristics of heartwood were examined by free compression tests. Specimens were compressed along the radial direction at 120 °C, and air-dried heartwood was dramatically deformed in the tangential direction. The plastic flow deformation of ABW was amplified by the presence of both extractives and moisture. In particular, the ethanol/benzene (1:2, v/v) soluble extractives in heartwood may have contributed to flow deformation. The results of the dynamic mechanical analysis showed that the air-dried heartwood exhibited softening in a temperature range over 50 °C. The ethanol/benzene-soluble extractives contributed to the softening behavior. The clarified deformation characteristics of ABW can contribute to more efficient material use of local forests.

Dynamics of Microstructure in the Early Stages of Ion Beam Assisted Film Growth

1991 ◽  
Vol 237 ◽  
Author(s):  
Harry A. Atwater ◽  
C. J. Tsai ◽  
S. Nikzad ◽  
M.V.R. Murty
Keyword(s):  
Thin Films ◽  
Epitaxial Growth ◽  
Recent Progress ◽  
Film Growth ◽  
Ion Beam ◽  
Surface Interactions ◽  
Low Energy ◽  
Early Stages ◽  
Semiconductor Thin Films ◽  
Nucleation Mechanisms

ABSTRACTRecent progress in low energy ion-surface interactions, and the early stages of ion-assisted epitaxy of semiconductor thin films is described. Advances in three areas are discussed: dynamics of displacements and defect incorporation, nucleation mechanisms, and the use of ion bombardment to modify epitaxial growth kinetics in atrulysurface-selective manner.

Within-process and seasonal changes during industrial production of high-density fibreboard. Part 1: Influence of wood species composition on polyoses in the products

Holzforschung ◽  
2012 ◽  
Vol 66 (5) ◽  
pp. 667-672 ◽  
Author(s):  
Martin Weigl ◽  
Rupert Wimmer ◽  
Thomas Ters ◽  
Roland Mitter ◽  
Thomas Kuncinger
Keyword(s):  
Wood Species ◽  
Galacturonic Acid ◽  
Middle Lamella ◽  
Strength Loss ◽  
High Density ◽  
Chemical Degradation ◽  
Structural Alterations ◽  
Compound Middle Lamella ◽  
Hemicellulose Degradation ◽  
Composition Changes

Abstract Industrially produced high-density fibreboard fibres are inhomogeneous in structure and chemical composition. Changes in polysaccharide chemistry during processing have an impact on strength loss, fibre separation and structural alterations. In the present study, carbohydrate composition of extracted wood chips and refiner fibres was monitored for a year at an industrial HDF plant. The polysaccharides were analysed via methanolysis and quantification of the monomeric sugars released. Significant reductions of arabinose, xylose, rhamnose and galacturonic acid were observed. The amount of glucose and extractable substances increased. The depletion of galacturonic acid and rhamnose indicates a degradation of pectin located in the compound middle lamella. The diminishing amounts of the other sugars and elevated extractive contents are a result of hemicellulose degradation. A pronounced seasonal variability of the data was observed depending on the processed wood species and degree of chemical degradation.

Ultrastructural Changes in the Compound Middle Lamella of Pinus thunbergii During Lignification and Lignin Removal

Holzforschung ◽  
2000 ◽  
Vol 54 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Jonas Hafrén ◽  
Takeshi Fujino ◽  
Takao Itoh ◽  
Ulla Westermark ◽  
Noritsugu Terashima
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Middle Lamella ◽  
Pinus Thunbergii ◽  
Ultrastructural Changes ◽  
Woody Tissue ◽  
Compound Middle Lamella ◽  
Lignin Removal ◽  
Transmission Electron ◽  
Early Phases

SummaryThe structure of the middle lamella inPinus thunbergiihas been studied by the rapid-freeze deep-etching (RFDE) technique in combination with transmission electron microscopy (TEM). The ultrastructure of the compound middle lamella was studied in the early phases of the development of woody tissue in the cambial and differentiating xylem, before the heavy incrustation with lignin had occurred. Lignified middle lamella in the xylem was studied both directly and after delignification. It was found that the structure of the unlignified middle lamella in the cambium/developing xylem consists of a fine irregular network probably containing pectin and hemicellulose. As a result of lignin incrustation, the middle lamella becomes increasingly dense and the surface structure of the fully lignified middle lamella appeared to be compact and partly covered with globular structures. After delignification of the lignified middle lamella a thin network with a different structure was revealed. This network probably mainly consists of hemicellulose. No microfibrils of the type that occurs in the primary and secondary walls were found in the middle lamella.

Proposed supramolecular structure of lignin in softwood tracheid compound middle lamella regions

Holzforschung ◽  
2012 ◽  
Vol 66 (8) ◽  
pp. 907-915 ◽  
Author(s):  
Noritsugu Terashima ◽  
Masato Yoshida ◽  
Jonas Hafrén ◽  
Kazuhiko Fukushima ◽  
Ulla Westermark
Keyword(s):  
Supramolecular Structure ◽  
Early Stage ◽  
Diphenyl Ether ◽  
Outer Part ◽  
Middle Lamella ◽  
Cellulose Microfibrils ◽  
Spatial Regulation ◽  
Compound Middle Lamella ◽  
Wide Contact ◽  
Guaiacyl Lignin

Abstract The structure of lignin in the compound middle lamella (CML) of softwood tracheids differs from that in the secondary wall (SW) in regard to the content of condensed structures (5-5′-biphenyl, dibenzodioxocin and 4-O-5′-diphenyl ether). In an early stage of cell wall formation, random coarse networks composed of thin cellulose microfibrils (CMFs), hemicelluloses, and pectin are formed in the CML, then globular p-hydroxyphenyl/guaiacyl lignin (HG-lignin) is deposited quickly into the network. The globular lignin is assumed to be a micellar aggregate of oligolignols folded at the β-O-4 bond with their phenolic ends on the outer part of the aggregate. When 3D clusters of the globules are deposited on the preformed network of polysaccharides, further growth of the oligolignols by endwise addition of new monolignols is spatially limited, so frequent condensation occurs between growing aromatic ends of adjacent HG-oligolignols within the globule and between the wide contact boundaries of the 3D clustered globules to produce a highly condensed supramolecule in CML. In SW, the folded G-oligolignols are deposited slowly in the narrow tubular space surrounding thick CMFs coated with hemicelluloses. Condensation occurs mostly between adjacent growing ends of the oligolignols within the tubular aggregates. Spatial regulation of condensation of folded polylignols is one of the factors producing a different supramolecular structure for CML lignin than for SW lignin.

The Golgi Apparatus in Development of the Mesoglea in Sertularia Pumila (Hydromedusae) Hydranths

1980 ◽  
Vol 38 ◽  
pp. 550-551
Author(s):  
Douglas J. Taatjes
Keyword(s):  
Golgi Apparatus ◽  
Middle Lamella ◽  
Columnar Epithelium ◽  
Sensory Cells ◽  
Secretory Cells ◽  
Stages Of Development ◽  
Early Stages ◽  
Vacuolated Cells

The early stages of development of the hydranth of Sertularia pumila is composed of an outer ectoderm and an inner gastroderm. These tissues are separated by an acellular middle lamella or mesoglea (1). The ectoderm is a columnar epithelium, with each cell having a centrally located nucleus (Fig. 1). In mature hydranths the ectoderm has secretory cells facing an outer chitinous hydrotheca and also stores sensory cells. The gastroderm is made of highly vacuolated cells which function in digestion. The ectodermal and gastrodermal cells are elongated with large vacuoles traversed by channels of cytoplasm which anchor the cells to the mesoglea (Fig. 1)

Comparative study of the topochemistry on delignification of Japanese beech (Fagus crenata) in subcritical phenol and subcritical water

Holzforschung ◽  
2016 ◽  
Vol 70 (11) ◽  
pp. 1047-1053 ◽  
Author(s):  
Masatsugu Takada ◽  
Yoshiki Tanaka ◽  
Eiji Minami ◽  
Shiro Saka
Keyword(s):  
Comparative Study ◽  
Subcritical Water ◽  
Beech Wood ◽  
Middle Lamella ◽  
Fagus Crenata ◽  
Insoluble Residue ◽  
Residual Lignin ◽  
High Solubility ◽  
Japanese Beech ◽  
Compound Middle Lamella

Abstract The delignification of Japanese beech (Fagus crenata) has been evaluated under conditions of subcritical phenol (230°C/1.2 MPa) and subcritical water (230°C/2.9 MPa). In the former, more than 90% of the original lignin was decomposed and removed, while in subcritical water, around half of the original lignin was left as insoluble residue. Ultraviolet (UV) microscopic images of the insoluble residues showed that the lignin in the secondary walls is decomposed and removed under both conditions. These images also revealed that the lignin in the compound middle lamella (CML) is resistant to subcritical water, but not to subcritical phenol. Results of alkaline nitrobenzene oxidation of the residual lignin confirmed these observations. Lignin in Japanese beech wood was phenolated by subcritical phenol, which was efficiently removed due to its high solubility in the reactant. It is obvious that CML is rich in condensed-type linkages facilitating rapid solvolysis by phenol. The topochemistry of the plant has a pronounced impact on its delignification behavior.

scholarly journals Chemical and ultrastructural changes in compound middle lamella (CML) regions of softwoods thermally modified by the Termovuoto process

Holzforschung ◽  
2014 ◽  
Vol 68 (7) ◽  
pp. 849-859 ◽  
Author(s):  
Jie Gao ◽  
Jong Sik Kim ◽  
Nasko Terziev ◽  
Ottaviano Allegretti ◽  
Geoffrey Daniel
Keyword(s):  
Middle Lamella ◽  
Ultrastructural Changes ◽  
Silver Fir ◽  
Cytochemical Staining ◽  
Compound Middle Lamella ◽  
Spruce Wood ◽  
Immunocytochemical Studies ◽  
Modified Lignin ◽  
Early Degradation ◽  
Histochemical Changes

Abstract Silver fir and Norway spruce wood have been thermally modified (TMW) for 3–4 h at 160°C, 180°C, 200°C, and 220°C by means of the thermovacuum process (Termovuoto), and the ultrastructural and chemical changes in the compound middle lamella (CML), including the middle lamella cell corner (MLcc) regions (CMLcc), were investigated. Severe anatomical and histochemical changes were prominent above treatment temperatures of 200°C; thus, woods treated at 220°C for 4 h were in focus. Immunocytochemical studies showed that noncellulosic polysaccharides, such as pectin, xyloglucan, xylan, and mannan, were significantly degraded in CMLcc regions of TMWs. After treatment, the CMLcc regions were composed almost entirely of modified lignin with increased amounts of acidic groups. With cytochemical staining for lignin, many electron dense particulates were detected in the CMLcc regions of TMWs, indicating early degradation/alteration by the Termovuoto treatment.

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