Determination of the physical, mechanical and fire properties of oriental beech (Fagus orientalis L.) impregnated with various fire retardant chemicals and coated with polyurea/polyurethane and epoxy resins

In the thesis study, the physical, mechanical and fire properties of Oriental beech (Fagus orientalis L.) wood impregnated with fire-retardants (FRs) and coated with polyurea (PU) and epoxy (EPR) were investigated. Wood specimens were impregnated with 3% aqueous solution of borax (BX), boric acid (BA), a mixture of (BA+BX), and ammonium sulphate (AS) according to ASTM 1413-76 standards, and then coated with PU and EPR. Then, physical tests such as oven-dry and air dry density were performed according to TS 2472 standard, color test according to ISO 7724-2 standard, surface gloss test according to ASTM D523-14 standard, surface hardness test according to ASTM D-4366 standard, accelerated-weathering test according to ASTM G154 standard, leaching and water absorption. Mechanical tests such as modulus of rupture, modulus of elasticity, and compression strength parallel to fibers were conducted TS 2474 and TS 2478, ISO 13061-17 standards, respectively. Fire test was applied according to ASTM E-69 standard. Also, scanning electron microscopy analyzes (SEM) of test specimens was applied. According to the density results, the highest oven and air-dry density value was determined in the test sample of Oriental beech wood impregnated with a mixture of (BA+BX) and coated with PU. According to color test results, decreases were observed in L values of all test specimens after accelerated weathering. The best color stability was determined in the test sample of Oriental beech wood impregnated with BX and coated with EPR. According to the results of surface gloss after accelerated-weathering, except for control, impregnated with AS and coated with EPR, and impregnated with a mixture of (BA+BX) and coated with EPR, it was observed that the gloss of all wood specimens were decreased. According to the results of the hardness test after accelerated weathering, the maximum decrease was determined in the Oriental beech wood test specimens coated with EPR, while the least decrease was determined in the Oriental beech wood test samples treated with a mixture of BX+BA and coated with PU. According to the leaching test results, besides the impregnation process at 10 0C, 22 0C and 40 0C, the coating with PU gave the most positive results against leaching. According to the results of the water absorption test, the test samples of Oriental beech wood treated with AS and coated with PU, and impregnated with BX and coated with PU gave the best results. According to the modulus of rupture and modulus of elasticity test results, the highest value was obtained in the Oriental beech test sample coated with PU. According to the results of compression strength parallel to the fibers, the highest value of the compression strength parallel to the fibers was determined in the Oriental beech sample coated with PU. According to the fire test results, the lowest weight loss was observed in the Oriental beech wood test sample impregnated with a mixture of (BA and BX) and coated with EPR. According to the results of SEM (scanning electron microscope), when the images of the control sample were examined, it was observed that a microscopically rough surface was obtained even though a macroscopically flat surface was noticed. It was observed that the Oriental beech test sample treated with epoxy (EPR) dries on the wood surface, resulting in a layered and rough surface as observed in the SEM images. When the SEM images of the Oriental beech wood treated with BA, BX and a mixture of BA and BX were examined, it was noticed that the impregnation material covered the cell cavities and cell walls. In addition, when the SEM images of the experimental samples of Oriental beech wood treated with AS were examined, it was noticed that the impregnation material is in the form of layers and particles in the cell cavities and cell walls.