Propriedades de madeiras termorretificadas / Properties of thermalrectified wood

AUTOR(ES)

Solange de Oliveira Araújo

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

07/05/2010

RESUMO

Heat treatment applied to the wood leads to the degradation and/or rearrangement of its principal chemical constituents, especially cellulose, hemicelluloses, and lignin, improving some properties such as dimensional stability, resistance to attack by wood decay organisms, and reducing the hygroscopicity. This occurs mainly by the OH groups degradation present in hemicelluloses, the most hydrophilic wood constituent. This study aimed to determine the thermal rectification effect on the hygroscopic equilibrium, density, wood shrinkage, Janka hardness, module of resistance to static flexural, and module of elasticity in static bending in the woods of Aspidosperma populifolium (Peroba mica), Dipteryx odorata (Cumaru), Eucalyptus grandis, Eucalyptus sp., and Mimosa scabrella (Bracatinga). The woods were heated among the plates of a press in a vacuum oven and in one oven with nitrogen. Experiments were carried out at room temperature, 180, 200, and 220C for one hour, after reaching the stipulated temperature. For all thermal rectified woods, a reduction in hygroscopic equilibrium content was observed, whose results indicated great potential of thermal treatment, mainly in oven with nitrogen. Cumaru species showed the lowest hygroscopic equilibrium. The basic density, in general, was affected only at temperatures of 200 and 220C, regardless of the used method. The volumetric contractions tended to decrease with increasing temperature, however, in some cases these contractions were increased, as in the treatments of the vacuum oven. The mechanical properties were affected by different ways. It was observed that the Janka hardness increasing was not so expressive. The MOR and MOE properties for some species had increased, while others do not. During heat treatments, Bracatinga species was less influenced. Already Eucalyptus Grandis and Eucalyptus sp. were the species that responded positively better to the thermal treatments at the most properties.

ASSUNTO(S)

tecnologia e utilizacao de produtos florestais termorretificação eucalipto bracatinga cumaru peroba mica thermalrectified eucalyptus bracatinga cumaru peroba mica

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