The term wood-based composite (WBC) is used to define a wide range of products in which wood is bonded together with other wooden or non-wooden materials
1 December 2015 in iForest - Biogeosciences and Forestry
Poor-quality Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) wood samples were heat treated with the aim of testing the improvement of wood quality that could increase their economic value. Wood properties were measured to assess quality in treated and non-treated materials, including density, hardness, anti-swelling efficiency (ASE), modulus of elasticity (MOE), modulus of rupture (MOR), and compression strength. The results showed higher dimensional stability in heat-treated wood, yet mechanical performance in compression and bending strength were only marginally affected by loss of density. Despite having a relatively low density after heat treatment, Corsican pine sapwood has potential in manufacturing higher-value products. In contrast, heat treatment applied to Douglas fir wood did not appear economically viable; insufficient differences were detected between the naturally desirable characteristics of this species and heat-treated samples.
Oriented strand board (OSB) are widely marketed for several applications, from building to packaging. The manufacturing of poplar OSB has recently started in Northern Italy, representing a relevant innovation in the sector, given that this product is usually made of coniferous wood. Thermal treatment is nowadays widely used for increasing the dimensional stability and the durability of wood. The drawback is, however, that the mechanical performance of the treated wood product is reduced. The objective of this research was to analyze the effect of thermo-vacuum treatment on the characteristics of poplar OSB. To this purpose, boards 15 mm thick and with a density of 590 kg/m3 were drawn from the standard production of the manufacturer and thermally treated under vacuum conditions at 190 °C for 2 h. Their mass loss, bending strength, modulus of elasticity, internal bond and swelling were determined. In addition, color change and wettability were studied before and after a weathering test. The thermal treatment significantly changed the properties of poplar OSB. The mass, the bending strength, the modulus of elasticity and the internal bond decreased with different intensities. The swelling after immersion in water decreased. The color switched toward a darker tone and the wettability decreased. After an accelerated weathering test (AWT), the color lightened, and the wettability increased. Overall, this study broadened the knowledge about the thermal treatment of this wood-based panel, which could enable new applications with particular attention to non-structural uses in humid conditions.
8 June 2005 in Forest@ - Rivista di Selvicoltura ed Ecologia Forestale
The article examines the OWAS method (Ovako Working-postures Analysis System) and its use for the evaluation of the risk of WMSD. In particular, a derived application has been validated in some case studies concerning forest harvesting both in mountain environment (silvicultural interventions in coniferous stands) and in flatland yards (final cut in poplar plantations). The variant of the method allows to attribute a specific class of risk to the postures assumed during the job and to calculate the relevant index of risk on the bases of the time frequency (by a multi-moment time study). The above index is expressed as a weighted value that ranges from 100 to 400 and the value obtained corresponds to a proportional level of risk and a consequent interventions to be implemented. Yards related to harvesting in coniferous stand have highlight an higher level of risk compared to those of poplar, with an average value of the OWAS index that respectively reached 191 and 140. In the first case the more critical operational phase was the on-site processing, while the slope and the morphology of the site have considerably influenced the assumption of inadequate postures by workers. In the yards of poplar the phases connected to the mayor risk were instead the falling operation followed by the logs measurement. The application of the OWAS method as it is proposed in this study, enables to acquire both ergonomic and yield information and to asses data in terms of working activity, job phase or single operator. It appears therefore a valid tool for the evaluation of the examined risk and could be usefully diffuse, like already happens in other countries, as an alternative or as a mean of comparison to other reference methods that register some problems of application in the forestry activities.