MATERIALS:

WOOD and PAPER

Simón, C.

Esteban, L. G.

de Palacios, P.

García Fernandez, F.

Martín-Sampedro, R.

Eugenio, M.E.


2015

Thermodynamic analysis of water vapour sorption behaviour of juvenile and mature wood of Abies alba Mill. Journal of Material Science. 50(22):7282-7292



Abstract:   The hygroscopicity and thermodynamic properties of juvenile and mature wood of Abies alba Mill. were studied through the 15, 35 and 50 °C sorption isotherms. The Guggenheim, Anderson and de Boer-Dent model was used to fit the isotherms. The thermodynamic parameters were obtained from the sorption isotherms by applying the integration method of the Clausius–Clapeyron equation. The chemical composition of both types of wood (extractives, lignin and carbohydrate polymer-cellulose and hemicellulose-content) was determined, and infrared spectroscopy and X-ray diffractograms were used to identify any chemical modifications and changes in the crystal structure of the cell wall. The mature wood has more cellulose and hemicellulose content and less extractives content than the juvenile wood. The shorter crystallite length in the mature wood creates a higher amount of amorphous zones and, as a consequence, a higher number of access areas to the –OH groups. The combination of these phenomena explains the different hygroscopic behaviour between the juvenile and the mature wood, as the latter has higher moisture content in the three isotherms. As regards the thermodynamic properties, the amount of energy involved in the sorption process is greater in the mature wood than in the juvenile wood.

 

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Román-Jordán, E.

Esteban, L. G.

de Palacios, P.

García Fernandez, F.


2016

Wood anatomy of Cupressus and its relation to geographical distribution. IAWA Journal. 37(1): 48-68



Abstract:   The wood anatomy of 14 species of Cupressus was studied to determine whether there is a pattern of wood anatomical diversity between the species from the North and Central American (western) region and the Eurasian (eastern) region. Xanthocyparis vietnamensis and Chamaecyparis nootkatensis (syn. Xanthocyparis nootkatensis) were also studied to compare their wood anatomy, given their recent inclusion by some authors in Cupressus. The arrangement of the axial parenchyma, morphology of the transverse end walls of the axial parenchyma, presence of ray tracheids, typology of the end walls of the ray parenchyma cells and ray height support to some extent the division of Cupressus into two large groups: the American group (western region) and the Eurasian group (eastern region), as proposed in molecular phylogenetic studies. The wood anatomy of Chamaecyparis nootkatensis shares the presence of ray tracheids and the same ray typology with American Cupressus, and has the same ray height as Eurasian Cupressus. In contrast, Xanthocyparis vietnamensis shares the absence of ray tracheids and the same ray typology with Eurasian Cupressus, and has the same ray height as American Cupressus.

 

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García-Iruela, A.

Esteban, L.G.

de Palacios, P.

García Fernandez, F.

de Miguel Torres,  A.

Vázquez Iriarte,  E.

Simón, C.


2016

Resinous Wood of Pinus pinaster Ait.: Physico-mechanical Properties. Bioresources. 11(2): 5230-5241



Abstract:   Pinus pinaster Aiton is the pine with the largest natural area of distribution in Spain and the species that sustains the country’s resin industry, with an annual average production of 3.2 to 3.5 kg per tree. After trees have been tapped, their wood has a high resin content and is of little use because of machining difficulties. For the first time, resinous wood of this species was characterized to compare its physico-mechanical properties with those of non-resinous wood. Significant differences were found in all the properties studied except modulus of elasticity. The resin produced by tapping decreased swelling, probably by reducing accessibility to the –OH groups and decreasing the available spaces during the capillary condensation phase. Similarly, tapping caused an increase in wood density and therefore in hardness, at the same time improving the mechanical properties.

 

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García-Iruela, A.

García Fernandez, F.

Esteban, L.G.

de Palacios, P.

Simón, C.

Arriaga, F.


2016

Comparison of modelling using regression techniques and an artificial neural network for obtaining the static modulus of elasticity of Pinus radiata D. Don. timber by ultrasound. Composites Part B: Engineering. 96:112-118



Abstract:   The traditional regression method was compared with an artificial neural network for obtaining the static modulus of elasticity (MOEstatic) of Pinus radiata timber using the dynamic modulus of elasticity determined by ultrasound in the first case and ultrasonic wave propagation velocity in the second case.

Whereas the regression model is capable of explaining 70% of the variability of the samples at best, the artificial neural network can explain 80%, indicating that this type of tool improves the estimate of MOEstatic when it is obtained using the ultrasonic technique.

 

Artículos científicos

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WEB Science

knowledge

UNIVERSIDAD POLITÉCNICA DE MADRID © 2017

Todos los contenidos incluidos en esta web pertenecen a la Universidad Politécnica de Madrid o a sus respectivos titulares, por lo que no se puede utilizar ningún contenido de la misma  sin el correspondiente permiso escrito.


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Juvenile and mature wood of Abies pinsapo Boissier: sorption and thermodynamic properties.   Wood Science and Technology. 49(4): 725-738

DOI 10.1007/s00226-015-0730-z



Abstract:   For industrial processes, it is important to study the hygroscopicity and thermodynamic properties of juvenile and mature wood. Samples of Abies pinsapo Boiss. collected in the natural areas of the species in Spain were used to study these properties in both types of wood. The equilibrium moisture contents were obtained, and the 15, 35 and 50 ºC isotherms were plotted following the Guggenheim–Anderson–Boer–Dent model. The thermodynamic parameters were calculated using the integration method of the Clausius–Clapeyron equation. Chemical analyses, infrared spectra and X-ray diffractograms were applied to assess chemical modifications and possible changes in the cell wall structure. The chemical composition of the mature wood shows a decrease in the lignin and hemicelluloses content and an increase in the extracts and a -cellulose. The sorption isotherms for the three temperatures studied are higher in the mature wood than in the juvenile wood. Causes of this include the higher content of a-cellulose, the higher crystallinity index and the shorter crystallite length in the mature wood. No difference was found between the juvenile and mature wood in relation to the point of inflexion where the multilayer starts to predominate over the monolayer (approximately 30 %). In terms of the thermodynamic properties, the heat involved is greater in desorption than in adsorption, and more heat is involved in the mature wood than in the juvenile wood.

 

Esteban, L. G.

Simón, C.

García Fernandez, F.

de Palacios, P.

Martín-Sampedro, R.

Eugenio, M.E.

Hosseinpourpia, R.


2015

Todos los contenidos incluidos en esta web pertenecen a la Universidad Politécnica de Madrid o a sus respectivos titulares, por lo que no se puede utilizar ningún contenido de la misma  sin el correspondiente permiso escrito.

UNIVERSIDAD POLITÉCNICA DE MADRID © 2017

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