The fibrillar orientation in the S2-layer of wood fibres as determined by X-ray diffraction analysis

Sahlberg, Ulla; Salmén, Lennart; Oscarsson, A.

doi:10.1007/bf00705923

Cited by 72 publications

(29 citation statements)

References 7 publications

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“…The MFA variation within a single annual growth is relatively well known. MFA is claimed to be the largest in the elements produced in the early stages of tree growth (earlywood) and it decreases, sometimes quite significantly in the summer, when the latewood develops Analogous studies on the same species of wood, but of Swedish origin (Sahlberg et al, 1997), showed that the average MFA in the walls of the early and late tracheids is only about 1 degree higher. For comparable MFA in the tracheids from the walls of early and latewood, the specifi c modulus of elasticity (MOE/ρ), determined for samples cut from different places of annual growth, should be similar.…”

Section: Rezultati I Raspravamentioning

confidence: 99%

Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

2014

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Section: Rezultati I Raspravamentioning

confidence: 99%

Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

2014

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“…• Les angles des microfibrilles des tissus ligneux à l'intérieur du cerne ont été forcés de telles sorte qu'ils diffèrent et soient compris entre 5 et 10 degrés pour le bois final et supérieur à 20 degrés pour le bois initial, répondant ainsi à certaines propositions bibliographiques [1], [31].…”

Section: Une Base De Donnée Des Paramètres Structurauxunclassified

Paramètres structuraux et/ou ultrastructuraux facteurs de la variabilité intra-arbre de l’anisotropie élastique du bois

Guitard

Gachet

2004

Ann. For. Sci.

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Résumé -La simulation de l'anisotropie élastique d'un bois résineux sans défaut est réalisée par empilement de trois échelles de descriptions, faisant passer successivement du niveau de la paroi cellulaire, à celui de chacun des tissus ligneux et enfin au niveau du cerne. Les modèles micromécaniques utilisés à chaque étape restent basés sur la recherche du solide élastique homogène équivalent, par des lois des mélanges simples appliquées à des assemblages série ou parallèle de sous domaines supposés homogènes. Un jeu utile de 17 paramètres réalistes, en regard de données bibliographiques variées, est optimisé sur la base des données caractéristiques élastiques anisotropes du « résineux standard ». L'outil de modélisation est adapté à l'analyse de la sensibilité des propriétés élastiques à la variabilité des paramètres adoptés bien que s'éloignant quelque peu de la stricte réalité ultrastructurale. Une originalité réside dans la schématisation de la paroi cellulaire en une couche unique, renforcée par un squelette de microfibrilles, dont l'orientation est empruntée à l'angle des microfibrilles de la sous couche S 2 ; le caractère rigidifiant du squelette, par comparaison à une structure renforcée par des fibres parallèles traduit les renforcements transverses de la paroi, le plus souvent imputés aux sous couches S 1 et S 3 . bois / anisotropie / élasticité / micromécanique / ultrastructureAbstract -Structural and/or ultrastructural parameters governing the variability inside the tree of the elastic anisotropy of wood. Three levels of modelling are introduced to simulate the elastic anisotropy of solid clear softwood, from the cell wall level, via wooden tissues, to the annual ring level. The micro-mechanical models used, at each step, are based on the homogeneous elastic equivalent solid method. Quite simple mixture laws are used for series or parallels assembling of two assumed homogeneous media. 17 realistic parameters are identified by optimisation on the base of given orthotropic elastic properties of the "standard softwood". The modelling tool allows analysing the sensibility of elastic parameters to the variability of internal structural parameters even if it doesn't express quite the ultrastructural reality. One of the originalities is include in cellular wall schematization by a unique layer, reinforcing by a microfibrille skeleton, in which the microfibrillar orientation belongs to S 2 layer. The stiffening of this skeleton, in front of a structure with parallels fibers, represents the cell walls tranverses reinforcements generally assigned to S 2 and S 3 layers.wood / anisotropy / elasticity / micro mechanics / ultrastructure

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“…This method was used in relation to various species by many researchers (Yang, Hazenberg 1994;Fabisiak 2005;Yeh et al 2006, etc.). On the submicroscopic level the most typically applied characteristic of wood structure for the determination of a boundary between juvenile wood and mature wood is the angle of cellulose fibrils in relation to the longitudinal axis of cells (Sahlberg et al 1997;Bhat et al 2001;Deresse et al 2003;Kojima, Yamamoto 2004;Fabisiak, Moliński 2007;Krauss 2010), while less frequently it is the degree of cellulose crystallinity (Marton et al 1972;Kocoń 1991;Andersson et al 2004; Nawrot 2010; Pazdrowski et al 2010;Szymański 2011). The parameter used most often in the determination of a boundary between the two wood zones in the case of physical properties is connected with specific density of annual rings and zones of early and late wood zones separately (Tassisa, Burkhardt 1998; Bao et al 2001;DeBell et al 2004;Clark III et al 2006;Mora et al 2007).…”

Section: Resultsmentioning

confidence: 99%

Analysis of coniferous species to identify and distinguish juvenile and mature wood

Nawrot¹,

Pazdrowski²,

Walkowiak³

et al. 2014

J. For. Sci.

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ABSTRACT:We conducted to describe methods used to differentiate the zones of juvenile and mature wood in stems of coniferous species and to present the importance of good identification of the shares of both types of wood to ensure a rational use of the raw material and final quality of wood products. This study describes in more detail a novel method to separate the juvenile and mature wood tissue in stems of European larch using cluster analysis in the form of the k-means algorithm. Moreover, guidelines were also shortly described for forest management which could result in a reduction of the share of juvenile wood in stems of forest trees.

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The fibrillar orientation in the S2-layer of wood fibres as determined by X-ray diffraction analysis

Cited by 72 publications

References 7 publications

Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

Variation in Mechanical Properties within Individual Annual Rings in the Resonance Spruce Wood (Picea abies (L.) Karst.)

Paramètres structuraux et/ou ultrastructuraux facteurs de la variabilité intra-arbre de l’anisotropie élastique du bois

Analysis of coniferous species to identify and distinguish juvenile and mature wood

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