Physical and mechanical properties of heat treated wood from Aspidosperma populifolium, dipteryx odorata and mimosa scabrella

Abstract

Heat treatment improves some wood properties namely: equilibrium moisture, dimensional stability and durability and mechanical properties. In this study, the heat treatment was applied to woods of three natural species from Brazil: Aspidosperma populifolium (peroba mica), Dipteryx odorata (cumaru) and Mimosa scabrella (bracatinga). The woods were heated in an oven under vacuum and under nitrogen, at 180, 200, and 220°C for one hour. The untreated and heat-treated woods were characterized in relation to equilibrium moisture content, basic density, shrinkage, Janka hardness, and bending MOR and MOE according to NBR 7190 standards. All the thermal rectified woods showed a reduction in the hygroscopic equilibrium content, especially when the heating was under vacuum from 13-15% in the untreated woods to 1-3% for vacuum treatment at 220 °C. The dimensional stability was improved to only a small extent e.g. volumetric shrinkage tended to decrease with increasing temperature. The mechanical properties were affected differently for the three wood species. Heat-treated cumarushowed increased Janka hardness, MOR and MOE; and peroba mica increased MOR and MOE but not Janka hardness; while bracatinga was less influenced by the heat treatment.

Effect of thermal treatment variables on the thermogravimetric properties of eucalypt wood

“…These authors verified mass losses of up to, respectively 9,7% and 9,3% for woods subjected to thermal treatments at 200 °C. Araújo et al (2016) heat-treated wood of different species native to Brazil -Aspidosperma populifolium, Dipteryx odorata and Mimosa scabrella -using treatment, temperature and atmosphere conditions similar to those of the present study. However, by using a treatment time of only one hour, the authors found mass loss values of at most 2,21% for treatment at 220 °C.…”

“…Araújo et al (2012), comparing wood treated in the press and in the vacuum oven, concluded that the thermal treatment in the press can produce undesirable effects on the mechanical properties, while the material treated in the vacuum oven with a controlled atmosphere obtained lower losses in the same properties. In the same way, Araújo et al (2016) also verified that heat treatment in a vacuum resulted in a modified wood that was less hygroscopic and significantly different when compared to wood treated under a nitrogen atmosphere. Candelier et al (2013) used vacuum and nitrogen atmospheres with a temperature of 220°C in both, and concluded that the effect of the vacuum allows the removal of products from the degradation of the volatiles produced by the wood.…”

Tropical Wood Dusts—Granulometry, Morfology and Ignition Temperature

“…The cumaru tree is very dense (950-1000 kg•m −3 ), tough, highly durable, and resistant to cracking when exposed to sunlight. Therefore, it is suitable for solid flooring, stair treads, furniture, and pool decks [32]. Moreover, it is frequently found in the states of Acre, Amapá, Amazonas, Pará, Rondônia, and Mato Grosso, as well as in neighboring countries like Guyana, Venezuela, Colombia, Bolivia, Peru, and Suriname [32].…”

Effect of Heat Treatment and Use of Aluminum Foil on Physical and Mechanical Properties of Wood

“…Heat-treated Cumaru showed increased Janka hardness, MOR and MOE. Peroba mica ISTEcS 2019 increased MOR and MOE but not Janka hardness; while Bracatinga was less influenced by the heat treatment [14].…”