Effects of termal treatment on the physical properties of Buchenavia sp. (branquilho) wood

This work aimed to evaluate the effect of heat treatment on the physical properties of wood from Buchenavia sp. The heat treatments were carried out at temperatures of 180 °C and 200 °C for 2 h. Apparent density (AD), basic density (BD), porosity (Ф), mass loss, longitudinal (LS), radial (RS), tangential (TS) and volumetric (VS) shrinkages and anisotropic factor (AF) were determined. The lowest values of basic density (0.67 g cm-3), apparent density (0.77 gcm-3), and porosity (43.3%) were observed for the wood treated at a temperature of 200 °C. Mass losses increased with increasing temperature and the highest values were observed under the condition of 200 °C (9.3%). The LS and AF was not affected by heat treatments. The mean values for RS (3.1%), TS (5.1%), and VS (9.1%) were reduced after the performance of heat treatments at temperatures of 180°C and 200°C, which did not differ from each other. The thermal treatments were able to reduce the dimensional instability of Buchenavia sp. Thermal treatments enhance the use of less prestigious Amazonian woods in the civil construction market.

Physicomechanical characterization and wood machining from 10 12-year-old Hevea progeny clones with potential for furniture

The objective of this work was to evaluate the physical, mechanical, and wood machining properties of 10 clonal progenies with 12 years of age aiming to produce furniture. A total of 10 progenies and three trees per progenies were used, totalling 30 trees analyzed. The basic density ranged from 0.404 g.cm-3 (IAC 301) to 0.495 g.cm-3 (IAC 326), being it considered a light wood. The anisotropy coefficient values ranged from 1.05 (IAC 40) to 1.68 (PB 330) considered low to medium dimensional instability allowing the use of wood to produce furniture with low dimensional movements. In the compression test most clones fall under class C30. For MOR and MOE, it was observed greater values for IAC 326 (11666 MPa) and GT1 (9575 MPa). In wood machining tests, slightly raised large and few defects on the surface, being them considered easy to work. The results obtained for Hevea brasiliensis, 12 years old, allow us to affirm that wood from a younger age is an alternative for furniture production and will consequently contribute to the reduction of the exploitation and degradation of native forests in Brazil for this purpose.

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

Although vegetation is increasingly used to mitigate landslide risks, how vegetation roots affect the landslide threshold of slope has rarely been explored, particularly in the case of lateral runoff. In this study, we established a two-dimensional saturated-unsaturated infiltration equation considering the hydraulic effects of vegetation roots. The analytical solution for the shallow unsaturated two-dimensional coupled infiltration of vegetated slope (VS) was obtained by a Fourier transform technique. The numerical method was used to evaluate the stability of VS caused by four root architectures, the rainfall amount, and the rainfall duration. Subsequently, the transformation law in runoff, vegetation evaporation, and landslide threshold was analyzed. The results indicate that the factor of safety (FOS) increases with increasing drying time and decreases with increasing depth; the minimum FOS is at the junction of the root-rootless zone. Runoff and vegetation evaporation are favorable for the shallow stability of VS. The time of the safe area is 35 h for rainfall amount 500 m in the uniformly root clay slope. Moreover, four landslide threshold curves that reflected the root architecture, rainfall amount, and rainfall duration are developed, which are more realistic than those created using one-dimensional instability modeling.

Review of Functional Treatments for Modified Wood

Wood modification is now widely recognized as offering enhanced properties of wood and overcoming issues such as dimensional instability and biodegradability which affect natural wood. Typical wood modification systems use chemical modification, impregnation modification or thermal modification, and these vary in the properties achieved. As control and understanding of the wood modification systems has progressed, further opportunities have arisen to add extra functionalities to the modified wood. These include UV stabilisation, fire retardancy, or enhanced suitability for paints and coatings. Thus, wood may become a multi-functional material through a series of modifications, treatments or reactions, to create a high-performance material with previously impossible properties. In this paper we review systems that combine the well-established wood modification procedures with secondary techniques or modifications to deliver emerging technologies with multi-functionality. The new applications targeted using this additional functionality are diverse and range from increased electrical conductivity, creation of sensors or responsive materials, improvement of wellbeing in the built environment, and enhanced fire and flame protection. We identified two parallel and connected themes: (1) the functionalisation of modified timber and (2) the modification of timber to provide (multi)-functionality. A wide range of nanotechnology concepts have been harnessed by this new generation of wood modifications and wood treatments. As this field is rapidly expanding, we also include within the review trends from current research in order to gauge the state of the art, and likely direction of travel of the industry.