No abstract

This study investigated the suitability of Gmelina arborea, low-density wood species and Leucaena leucocephala, high-density wood species for the production of 6 mm thick Inorganic-bonded flake-boards. Flake-boards were made at three levels of curing reagent and board density to get nine experimental flakeboards for each species. The flake-boards were subjected to modulus of rupture, thickness swelling, water absorption, and accelerated aging tests. Thickness swelling, water absorption and accelerated age of boards decreased as curing reagent and board density increased whereas modulus of rupture of boards from each species increased proportionately with Gmelina arborea having higher strength. The performance of boards produced at the highest level of curing reagent and board density were better as they showed highest resistance to dimensional movement and bending force. Flakes from both species are suitable raw materials for flakeboard manufacture, which could be used as substitute to sawn timber in core and low-cost housing construction.

Rubber wood utilization in Nigeria has become a viable alternative because of over-exploitation of more durable species. The use of rubber wood in its native form has some disadvantages including dimensional instability, low durability and susceptibility to weathering in outdoor uses. However, it may be improved through chemical modification such as acetylation. In this study, we revealed the effectiveness of acetylation on the protection of rubber wood against weathering in terms of weight loss (WL), colour change, lignin degradation, and mechanical properties. Acetylation was carried out using two different reaction times to achieve weight percent gains (WPG) of around 7% and 10%. Understanding of the effect of acetylation and subsequent weathering on mechanical properties was enabled by analysing wood chemistry with Fourier transform infrared (FTIR) analysis and Raman spectroscopy. The mechanical tests of weathered unmodified and acetylated rubber wood revealed a decrease of tensile stiffness of the unmodified samples as a function of weathering time, while stiffness was retained for the acetylated samples. Weathered unmodified samples showed a bi-phasic stress-strain pattern with a high strain at breakage indicating a slippage of fibres under stress due to degradation of the middle lamella. This was hardly visible for acetylated samples. Thus, acetylation was shown to be effective for protecting rubber wood used in outdoor conditions.

• This study was carried out to investigate the effi ciency of lumber recovery among

The study examined the impact of thermal treatment on anatomical and mechanical properties Ricinodendron heudelotii wood. Wood samples were oven dried at 105°C and cooled in a desiccator to a constant weight before the thermal treatment. Heat treatment of wood was carried out in a Furnace at 120°C, 140°C and 160°C for 45 minutes and 90 minutes. The Density, Modulus of Elasticity (MOE), Modulus of Rupture (MOR), and the anatomical properties were assessed. The results for Density of Ricinodendron heudelotii wood showed decrease from 279 kg/m3 (120°C at 45 minutes) to 256 kg/m3 (160°C at 90 minutes) while that of control was 281 kg/m3   which was lower than the treated samples. The increase in temperature with time had effect of the color of wood as it changed from creamy white to dark brown. The image of untreated and treated samples showed no significant changes within and among treatment groups as there was no effect of treatment time and exposure on the samples. The MOE of heat treated Ricinodendron heudelotii increased from 2064.84 N/mm2 (140°C for 45 minutes) to 2271.93 N/mm2 (160°C for 90 minutes) while MOR decreased from 40.56 N/mm2 (140°C for 90 minutes) to 33.53 N/mm2 (160°C for 90 minutes). The study revealed that the wood could be used in a light furniture as unnecessarily heavy wood is not important. Also, the study proved effective in improving the modulus of elasticity of the wood.