WOOD RESEARCH Volume 67, Number 1, 2022
Róger Moya and Carolina Tenorio

Reduction of effect of growth stress presence using endless screw during kiln drying and steaming and heating treatment in log before sawing

The relaxation of growth stress in trees growing in fast-growth conditions, as plantation in tropical areas, affects lumber quality during of sawing or drying process. It was evaluated two pretreatments (heating and steaming application) before sawing process and endless screw use to maintain the boards pressed during drying of Dipteryx panamensis and Hieronyma alchorneoides wood with objective to reduce the effects of relaxation of growth stress. The results showed endless screw is used to maintain the boards pressed, the moisture content (MC) or drying rate did not vary. The use of endless screws with daily adjustment during drying produced a reduction of cup, check and split defects in lumber and this treatment is ccompanied with a pre-treatment before sawing (heating or steaming treatment) decreased the incidence of drying defects. Then the use of both treatments is an opportunity to reduce the effects of relaxation of growth stress on the quality of the wood of D. panamensis and H. alchorneoides from fast-growth plantation conditions.

WOOD RESEARCH Volume 62, Number 4, 2017
Agnieszka Jankowska, Magdalena Reder, and Tomasz Gołofit

Comparative study of wood color stability using accelerated weathering process and infrared spectroscopy

The objective of this study was to investigate effects of artificial weathering on color stability of six tropical wood species: Apuleia leiocarpa (Vog.) Macbride, Bagassa guianensis Aubl., Dipteryx odorata (Aubl.) Wild., Hymenea courbaril/Linn., Manilkara bidentata A. Chev., Tabebuia sp. Chemical composition of weathered wood was also studied by FT-IR spectra. With the progressive artificial weathering color of wood changed gradually. Hymenea courbaril Linn. wood occurred the greatest range of the total color change. The largest changes in intensity of the wood color took place at the beginning of artificial weathering process. FT-IR analysis indicated the occurrence of lignin and hemicellulose oxidative changes resulting in formation of carbonyl and carboxyl compounds during weathering. Oxidation products are the main cause of wood surface discoloration. Additionally, changes suggesting depolymerisation of cellulose were identified as well.

WOOD RESEARCH Volume 66, Number 1, 2021
Beatriz Segura-Elizondo and Róger Moya

Wood properties comparation of Cedrela odorata from trees in agroforestry and in pure plantation

The aim of this work was to compare the general, physical, mechanical, chemical and energy properties of the wood from Cedrela odorata trees growing in two agroforestry condition (tree-agroforestry) with Theobroma cacao (9 and 10 years old), with a ten-year-old C. odorata tree growing in pure plantation (tree-plantation). The results showed that there growing in agroforestry presented higher heartwood diameter (6.7 to 7.6 cm) and heartwood (approx. 17%) and lower bark (12-13%) and sapwood (69-70%) percentages than trees in pure plantation. In addition, this tendency was observed through different heights of the tree. Moreover, wood from 9-tree-agroforestry presented highest specific gravity and volume shrinkage. Then wood from this growing condition presented highest strength in axial hardness and flexure relative, and extractives in cold water and ethanol-toluene. No differences were observed between the energy properties. In general, wood from trees in agroforestry present better properties than the trees growing in pure plantation. According with these results, the potential of agroforestry systems relative to pure plantations, as regards to differences in tree growth produced by crop fertilization, pruning and other management measures to which the agricultural crop is subjected, which can give the wood qualities different from those found at earlier ages.