Physico-mechanical properties of selected species subjected to thermo-oil treatment

Abstract

This research examined the effect of thermal modification on the physical and mechanical properties of Gmelina arborea, Triplochiton scleroxylon, and Hevea brasiliensis using palm kernel oil. Colour change, density, compression strength, Modulus of rupture, and modulus of elasticity were measured. Results showed that at temperatures between 170^oC and 190 ^oC, average density values varied from 375.83 kg/m³ to 431.70 kg/m3 for obeche, 470.56 kg/m³ to 474.59 kg/m3 for Gmelina arborea and rubber from 539.17 kg/m3 to 510.47 kg/m³. The Average Compression strength values varied from 25.38 N/mm² at 27.50 N/mm² for obeche, 42.87 N/mm² to 45.16 N/mm² for Gmelina arborea, and rubber from 28.83 N/mm² to 25.37 N/mm². The Average Modulus of Elasticity values varied from 4264.63 N/mm² at 170°C to 4891.66 N/mm² for obeche, 8496.72 N/mm² to 7405.64 N/mm² for Gmelina arborea, and rubber from 5159.17 N/mm² to 4613.07 N/mm². The Average Modulus of Rupture values varied from 67.32 N/mm² to 60.45 N/mm² for obeche, 78.54 N/mm² to 74.52 N/mm² for Gmelina arborea, and rubber from 63.83 N/mm² to 58.16 N/mm². It was observed that dimensional stability was enhanced when thermally modified. The colour of wood samples became darker after treatment therefore, thermal modification is recommended for applications where the appearance and high strength of wood are not paramount.