Properties and set-recovery of surface densified Norway spruce and European beech

The chemistry and wetting behaviour of surface densified wood were investigated using FT-IR spectroscopy and contact angle analyses. Furthermore, set-recovery of the surface under conditions of fluctuating humidity was measured and quantitative microscopy analyses were undertaken. FT-IR indicated that no significant chemical changes took place during the densification process. However, the wettability of the densified surfaces was significantly lower than unmodified surfaces. Following several high humidity-oven dry cycles, it was found that this densification process was almost completely reversible, i.e., there was full set-recover

Surface modification of wood using friction

The potential of linear vibration friction as an innovative means of producing increases in both surface density and surface hardness was explored. The influence of processing pressure and time on the degree of surface densification, surface hardness and surface elasticity was investigated. It was found that surface hardness (measured as Brinell hardness) was positively correlated with densification ratio. Furthermore, surface elasticity, that is the ability of the surface to recover elastically after indentation during the Brinell hardness test, could be increased by up to 33% depending on the degree of surface densification. The temperature rise due to friction was also studied. During processing, it was found that the temperature rise on both the radial and tangential surfaces was positively correlated with the processing pressure and time

Surface modification of wood using friction

The potential of linear vibration friction as an innovative means of producing increases in both surface density and surface hardness was explored. The influence of processing pressure and time on the degree of surface densification, surface hardness and surface elasticity was investigated. It was found that surface hardness (measured as Brinell hardness) was positively correlated with densification ratio. Furthermore, surface elasticity, that is the ability of the surface to recover elastically after indentation during the Brinell hardness test, could be increased by up to 33% depending on the degree of surface densification. The temperature rise due to friction was also studied. During processing, it was found that the temperature rise on both the radial and tangential surfaces was positively correlated with the processing pressure and tim

Frank Pierobon, L’Œil solaire : l’allégorie platonicienne de la Caverne

La métaphysique est-elle fille de l’écriture ? C’est une des questions au centre de ce livre où Frank Pierobon entend jeter les bases d’une phénoménologie de cet impensé de la philosophie : les conséquences, sur la pensée elle-même, de la pratique massive et normative de l’écriture. Par ce terme, « écriture », si la pratique philosophique est la première visée, l’auteur implique également toutes les pratiques scripturales, y incluant aussi bien le dessin et le diagramme mathématique comme sig..

Max Armengaud - Antichambre

Accompagnant une exposition rétrospective au Château d’eau de Toulouse, l’ouvrage éponyme Antichambre propose de revisiter certains des « portraits d’institutions » réalisés par Max Armengaud (né en 1957) depuis trente ans. Huit séries sont présentées, donnant l’occasion de s’imprégner du travail du photographe, cohérent à la fois par sa thématique répétitive (décrire une institution à travers, et entre, les portraits de ceux qui l’habitent et qui la font) et par ses procédures toujours sembl..

Cocoboard: Biobasierte Platte auf Basis von Kokosfasern

Les matériaux de construction à bas prix sont inabordables aux Philippines. Une matière fibreuse bon marché est présente en grande quantité: la fibre de noix de coco. Pourrait-on utiliser cette fibre pour la fabrication de panneaux de construc- tion? En collaboration avec la fondation Hilti et le Fond National Suisse de la Recherche Scientifique, une équipe d’ingénieurs bois, d’agronomes et d’économistes a mis au point une technologie de production de panneaux de haute et de basse densité. Les premiers essais industriels sont en cours.Erschwingliches Baumaterial ist auf den Philippinen schwer erhältlich. Ein günstiges, faserartiges Material ist aber in grosser Anzahl vorhanden: die Faser der Kokosnuss. Kann diese Faser für die Herstellung von Platten verwendet werden? In Zusammenarbeit mit der Fondation Hilti und dem Schweizerischen Nationalfonds (SNF) hat eine Gruppe aus Holzbauingenieuren, Agronomen und Ökonomen eine Technologie zur Produktion von Platten mit hoher und niedriger Dichte entwickelt. Die ersten Industrietests sind im Gang

Martin Scorcese

Depuis 1990 et la création de sa Film Foundation, la figure de Martin Scorcese se construit de plus en plus, au moins en Europe, comme celle d’un parangon du cinéaste cinéphile. Il était donc naturel que la cinéphilie lui rende hommage, et c’est chose faite avec l’exposition organisée par Kristina Jaspers et Nils Warnecke pour la Deutsche Kinematek de Berlin, reprise cet hiver à la Cinémathèque française de Paris dans une version retravaillée par Matthieu Orléan. Le livre publié par la Cinéma..

"Wir wollen Leute ausbilden, die anders denken"

Ab September 2022 gibt es an der BFH den Master «Circular Innovation and Sustainability». Damit werden Manager*innen ausgebildet, welche die Entwicklung der Kreislaufwirtschaft vorantreiben sollen. Ein Gespräch mit Frédéric Pichelin, Mitglied des Kernteams Master CIS über die Schwerpunkte des Studiengangs und die grosse Bedeutung der Kreislaufwirtschaft

Characterization of wood-adhesive bonds in wet conditions by means of nanoindentation and tensile shear strength

The performance of adhesive-hardwood bonds can often be sensitive to humidity and temperature variation. Therefore, it is frequently challenging to achieve standard requirements for structural applications. To gain a better understanding of the wood-adhesive bond, the properties of the individual constituents as well as the local interface of European beech (Fagus sylvatica L.) wood cell walls in contact with structural adhesives were analyzed by means of nanoindentation. These results are compared to classical lap-shear strength. As adhesives two different one-component polyurethane adhesives (1C PUR) and a phenol resorcinol formaldehyde adhesive (PRF) were used. In one case, the beech wood was additionally pre-treated with an adhesion-promoting agent (primer) prior to bonding with 1C PUR. Beech wood joints were analyzed subsequent to several treatments, namely standard climate, after wet storage and in re-dried conditions. In addition, the influence of the primer on the hydroxyl accessibility of beech wood was investigated with dynamic vapor sorption (DVS). The lap-shear strength revealed good performance in dry and re-dried conditions for all adhesives on beech. Both polyurethane adhesives obtained deficits when tested in wet conditions. The use of a primer significantly improved the PUR performance in wet condition. DVS experiment demonstrated a decrease in hydroxyl group accessibility when using a high primer concentration. As novelty, nanoindentation was used for the first time to characterize the local wood–adhesive-interface properties in wet conditions. Nanoindentation showed that all tested 1C PUR perform quite similar in room climate, while PRF achieves considerable higher values for reduced E-modulus and hardness. Wet storage led to a considerable reduction in mechanical properties for all adhesives, while the highest relative change was observed for PRF. After re-drying, the adhesives re-gained a large part of their original mechanical properties in room climate. No distinct effect of the primer on the local micromechanical properties could be detected with nanoindentation in terms of specific work of indentation

UHTC coatings obtained by plasma spraying: Characterization and oxidation behavior

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