Search

Thermal modification is a technique that can be used to increase the resistance of wood to the biodeterioration processes. In this context, the objective of this study was to evaluate the durability of Parkia pendula (angelim-saia) and Simarouba amara (marupá) woods thermally modified in rotting field tests and by the action of natural weathering. The tests were carried out in the Brazilian Amazon region, in the Mato Grosso State. The thermal modification of the wood was set with four treatments: control (T1); electric-oven treatment, 180°C for 3 h (T2); combination of autoclave and electric-oven, 125°C for 3 h, and 180°C for 3 h respectively (T3), and immersion in vegetable oil, 180°C for 3 h (T4). The samples were partially buried for the field rotting assays, and the mass loss and deterioration index were seasonally evaluated after the experiment was installed. These analyses were performed on the same samples which has been exposed to rotting essays. The action of natural weathering was assessed through the CIELAB* colour system. T4 was the most efficient for increasing the resistance to biological deterioration, under the tested conditions. T2 and T3 treatments conferred higher colorimetric stability for both types of woods after natural weathering, under the tested conditions. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Charcoal is one of the most essential energy sources in the world and is used mainly for domestic and industrial purposes. Brazilian charcoal production occurs in rudimentary masonry kilns without concern for process safety or energy waste. This work aimed to develop a mini carbonization system of three kilns coupled to a vertical smoke burner for optimized and environmentally correct charcoal and wood vinegar (WV) production on small farms. The project was divided into three parts for dimensioning: the three-kiln set, the WV condensing device, and the smoke burner. The condenser was designed following the procedures from the standards of TEMA (Tubular Exchangers Manufacturers Association); ASME (Society of Mechanical Engineers of the United States) Section VIII, Division 1; and the NR-13 (Regulatory Standard) of ABNT (Brazilian Association of Technical Standards). In contrast to the current scenario, in which primitive carbonization technologies are still employed, bringing about low charcoal yields and significant pollution release, the use of a mini-kiln that allows charcoal production and wood vinegar recovery combined with pollutant smoke burning is an interesting eco-friendly solution. Thus, the mini-kiln model presented here brings a low cost and environmental safety to the charcoal production chain, reaching sustainability parameters and offering higher income opportunities to small producers. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pre-treatments reduce energy consumption for the production of cellulose micro/nanofibrils (MFC/CNF). The objective of this work was to study sodium silicate (Na2SiO3) solutions as pre-treatment for Eucalyptus sp. and Pinus sp. pulps. The treatments were identified as EUC SS 5 % and EUC SS 10 % when 5 and 10 % Na2SiO3 were used, respectively. The treatments for Pinus sp. pulp were identified as PIN SS 5 % and PIN SS 10 %, and the untreated pulps as EUC control and PIN control. The lowest hemicellulose content was obtained for PIN SS 10 %. EUC SS 10 % showed the highest WRV values. EUC SS 5 % (∼ 4100 kWh/t) and EUC SS 10 % (∼ 4200 kWh/t) showed the lowest energy consumption. The pre-treated MFC/CNF showed diameters below 45 nm. The lowest viscosity was obtained for EUC SS 5 % (5.5 cP) and the highest for PIN control (7.7 cP), respectively. The zeta potential indicated moderate stability of the suspensions (−24 ∼ −18 mV). Na2SiO3 showed efficiency for MFC/CNF production due to reduced energy consumption and better individualization. The suspensions have compatible characteristics for application as a stabilizer of colloidal systems and reinforcement of composites. [ABSTRACT FROM AUTHOR]

The present work evaluates the production of wood–cement particleboards (WCBs) with addition of coconut-husk fibers. Trees of a Eucalyptus urophylla × Eucalyptus grandis hybrid were used as wood source. Boards were produced with addition of five coconut-fiber levels (0%, 10%, 20%, 30%, 40% and 50%) to replace the original wood, in a completely randomized design. From each board, specimens were taken to perform physical–mechanical tests (density, water absorption, thickness swelling, static bending, compression strength, and internal bond strength). The chemical characterization of the coconut fiber – in particular the total amount of extractives – in cold and hot water and an organic solvent, along with determination of lignin, holocellulose and ash amounts. The results showed that the addition of coconut fibers significantly affected the physical–mechanical properties of the boards. For the physical properties, the addition of coconut fibers improved the dimensional stability with the respective decrease in water absorption and thickness swelling. For mechanical properties, a decrease in the MOR and MOE was observed as the percentage of coconut fibers increased, most likely due to a poor interaction between the particles and the cementitious matrix. The resulting WCBs were suitable for nonstructural and indoor uses. [ABSTRACT FROM AUTHOR]

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The work aimed to evaluated the effect of heat treatment on physical and mechanical properties of Hymenolobium petraeum Ducke wood. For this, were manufactured samples with 25.0 × 9.0 × 1.7 cm which were submitted to different heat treatments, with two temperatures (180 and 200 °C) and two exposure times (2 and 4 hours), besides the control samples (without the heat treatment). After the treatments, each sample were submitted to the assays with withdrawal of subsamples for the physical (density, mass loss, equilibrium moisture content and dimensional stability) and mechanical properties (static bending and compression parallel to grain). The heat treatment provided a weight loss of wood, with the higher temperature treatments displayed the greatest losses. However, it proved effective to decrease the equilibrium moisture content and the dimensional stability. The mechanical properties were not affected to the heat treatment. [ABSTRACT FROM AUTHOR]