Effects of impregnation and heat treatment on density, bending and compression properties of black pine (Pinus nigra Arnold) wood

Abstract

ABSTRACT This study aims to study the improvement in the properties of heat-treated wood material by impregnation. For this purpose, black pine (Pinus nigra Arnold) wood specimens were modified in two stages: impregnation with 1%, 3% and 5% of diammonium phosphate (DAP) and sodium carbonate (SC) compounds followed by heat treatment at four different temperatures. Test specimens were pre-treated with solutions of different pH values of either DAP or SC solutions according to the immersion method and they were exposed to heat treatments at 150°C, 170°C, 190°C and 210°C for 3 h. Some physical and mechanical properties were determined in combined treated specimens with air-dried density, compression strength parallel to grain (CS) and bending strength (MOR). The test results indicated that, as regards the effect of the heat treatment, the mechanical strength decreased due to the increase in temperature, while the losses in the CS were fewer than those of the MOR. In addition, generally combined treatments increased the mechanical properties of the specimens, especially at lower and moderate heat treatment temperatures. Moreover, the SC compound showed more favorable results against the reducing effect of the heat treatment on mechanical strengths.