A Study of the Physical and Mechanical Properties of Scots Pine Fire Retardant Treated Thermowood

In the present study, the physical and mechanical properties of fire retardant treated thermowood of scots pine (Pinus sylvestris L.) was evaluated. Specimens were impregnated with %7 solution of borax fire retardant for 40 minutes at the pressure of 4 bars. Heat treatments were carried out at temperatures of 170 ◦C and 190 ◦C for 3 hours. Surface quality, color change and glueline shear strength of specimens were verified. Surface roughness according to ISO-4287 and color change according to ASTM D-2244 were studied with variables of impregnation and heat treatment temperature. Glueline shear strength was measured according to ASTM D-905 with variables of impregnation, heat treatment temperature and resin type. Results indicated that borax fire retardant increased surface roughness while heat treatment decreased surface roughness. As heat treatment temperature increased, the surface roughness diminished. Color of specimens became darker as the temperature of heat treatment was raised. Fire retardant treated thermowood showed the most color change. Impregnating with borax weakened the bonding strength. Glueline shear strength in fire retardant treated specimens was higher than fire retardant treated thermowood. Fire retardant treated thermowoods displayed greater glueline shear strength than thermowoods.