Impact of heat treatment on physico-mechanical properties of torrefied Antholceistha djalonensis wood

IRG/WP 17-40811

E A Iyiola, B Olufemi, J A Fuwape, J M Owoyemi

Thermal modification at relatively high temperatures is an effective method to improve the dimensional stability and mechanical properties of wood. This study was carried out to investigate the impact of heat treatment on the physic-mechanical properties of torrefied Anthocleistha djalonensis wood. Thirty nine defect-free specimens of dimensions 20 mm × 20 mm × 60 were prepared for the determination of dimensional stability and compression test. For the evaluation of static bending strength tests, thirty nine specimens of dimensions 20 mm × 20 mm x 300 mm were prepared. The specimens (at constant m.c. of 12%) were thermally treated at temperatures of 120, 140, 160 and 180oC for 60, 90 and 120 minutes duration. The wood samples were introduced into the furnace and ramped to the temperature at which the actual heat treatment occurred. Density, Moisture content, Weight Loss, Void Volume, Water absorption, Volume swelling, Modulus of Elasticity (MOE), Modulus of Rupture (MOR), Maximum Compression Strength and Hardness of the torrefied and untreated samples were investigated. Heat treatment revealed a clear effect on the physical and mechanical properties of hardwood species. The mean values of the density showed a significant reduction as a function of treatment condition. An increase of the modulus of elasticity during the bending test has been noticed after heat treatment. The minimum MOE value of samples was 3266 N/mm2at 120 °C for 1h while the maximum MOE of samples was 3908 N/mm2 at 160 °C for 2h , whereas the compressive strength parallel to the fibre increased after heat treatment. it can be concluded that thermal modification improves dimensional stability and mechanical properties of wood samples. Technological properties generally decreased with increasing heat-treatment intensity. The modulus of Elasticity of the wood were greatly influenced and enhanced by temperature.

Keywords: thermal modification, mechanical properties, Anthocleistha djalonensis, compressive strength

Conference: 17-06-04/08 Ghent, Belgium

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