Finger-jointing of green Eucalyptus globulus L. wood with one-component polyurethane adhesives

The use of glued finger joint in green wood, directly from the sawing process, would open the possibility to obtain glued timber from small-sized wood, achieving an efficient use of the original raw material. The gluing of finger-jointed green wood, with moisture content above the fibre saturation point, may improve the efficiency and the manufacturing process of glulam or joinery. This may be especially beneficial for a hardwood such as Eucalyptus globulus L., which is a globally important forest resource, but is a challenging wood to dry. This article presents a study on the possibility to develop finger joints with wood in green state. To compare them, conventional finger joints on dry wood and solid boards without end joints were also manufactured. Cold-setting and fast-curing commercial one-component polyurethane adhesive systems were used. Finger-jointed samples were tested to determine mean and characteristic values (5th percentile) of density, bending strength and modulus of elasticity, and the results were analysed and discussed. Green-glued joints showed no statistically significant differences compared to the solid boards and improved strength properties with respect to dry-glued joints.

CHARACTERIZATION OF PAULOWNIA TOMENTOSA STEUD TREES GROWN IN A 5-YEAR-OLD PLANTATION IN COSTA RICA

Paulownia tomentosa is utilized in Costa Rica and other countries for wood production and as feedstock for biomass, though the variation of wood properties for this species is scarcely known. In this work, the specific wood properties of a 5-year-old plantation in Costa Rica were studied. The results showed that bark and pith percentage and wood specific gravity (SG) increased with tree trunk height, while the proportion of heartwood, green wood density and green wood moisture content decreased. The average wood SG was 0.26 and tended to increase from pith to bark. Low wood SG values are related to low mechanical properties, with the advantage that wood shrinkage is low as well, which gives this wood species the potential to be utilized for reforestation purposes in Costa Rica. The gross calorific value of this species was 17809 kJ/kg, which, together with its cellulose and extractives contents, recommend P. tomentosa as a biomass source for energy production.

Study of Mechanical Properties of PHBHV/Miscanthus Green Composites Using Combined Experimental and Micromechanical Approaches

In recent years the interest in the realization of green wood plastic composites (GWPC) materials has increased due to the necessity of reducing the proliferation of synthetic plastics. In this work, we study a specific class of GWPCs from its synthesis to the characterization of its mechanical properties. These properties are related to the underlying microstructure using both experimental and modeling approaches. Different contents of Miscanthus giganteus fibers, at 5, 10, 20, 30 weight percent’s, were thus combined to a microbial matrix, namely poly (3-hydroxybutyrate)-co-poly(3-hydroxyvalerate) (PHBHV). The samples were manufactured by extrusion and injection molding processing. The obtained samples were then characterized by cyclic-tensile tests, pycnometer testing, differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, and microscopy. The possible effect of the fabrication process on the fibers size is also checked. In parallel, the measured properties of the biocomposite were also estimated using a Mori–Tanaka approach to derive the effective behavior of the composite. As expected, the addition of reinforcement to the polymer matrix results in composites with higher Young moduli on the one hand, and lower failure strains and tensile strengths on the other hand (tensile modulus was increased by 100% and tensile strength decreased by 23% when reinforced with 30 wt % of Miscanthus fibers).

Concept of tree in Varlam Shalamov’s “Kolyma tales” and their translations into Italian

This paper aims to analyze the metaphorical meaning of phytonyms in Russian and Italian languages and the Russian-Italian version of Shalamov’s literary text. After analyzing the author’s style, we examined the thematic group of phytonyms and their use in the “Kolyma tales.” We divided trees into two categories: 1. plants - the main characters represented by a system of metaphors; 2. plants occurring once or twice in the tales and in a neutral way (even having significant meanings in the Russian culture). The phytometaphor of the stlanik (dwarf cedar), from the first category, is a leitmotif in almost all Shalamov’s works, especially in the “Kolyma tales” and in the “Kolyma notebooks,” where the phytonym has a complex symbolic meaning characteristic of the word tree in general (life, green, wood) but also linked to the author’s view of the world. In Shalamov’s works, the tree reflects not only the picture of the northern nature but also takes on special meanings more related to the prisoner and his physical and psychological characteristics. Thanks to Shalamov, the lexeme stlanik was introduced into the Russian linguistic view of the world. Also, the analysis of the adequate interpretation of this keyword in the translations of the “Kolyma tales” into Italian revealed that when the translation contains a description of parts of this phytonym, for example, branches, the metaphor of the original text is sometimes lost in the translation.