Evaluation of black pine (Pinus nigra Arnold.) barks in the production of insulation board

Materials used in buildings to provide heat and sound insulation are developing depending on technological innovations, and in recent years the use of environmental and ecological materials has gained importance. Waste tree bark obtained by debarking of tree trunks are generally used in energy production. In this study, insulation boards suitable for heat and sound insulation were produced by using polymeric methylene diphenyl di-isocyanate (P-MDI) urea formaldehyde (UF) resin from black pine (Pinus nigra Arnold.) bark. Decorative boards were prepared by coating the surfaces of the produced insulation boards with wood veneers. Some of the physical, mechanical, heat and sound conductivity properties were determined for veneer coated and uncoated boards. When the results obtained are evaluated, the highest increase in the density values with the coating of the board surfaces was calculated as 18.75% and 6.06% for the 20 mm and 30 mm thicknesses, respectively. The highest density-increase due to the 100 kg/m3 increase in the board density was 37.50% (20 mm) and 33.33% (30 mm). In the production of insulation boards, it was determined that the water absorption (WA) and thickness swelling (TS) values of 2 and 24 hours decreased with the increased P-MDI ratio in the glue mixture in general. This non-linear decrease, especially for TS values, reached the highest level in the board groups in which P-MDI was added at different rates (1%, 2%, and 3%) to 7% UF, and the lowest TS values were obtained. The lowest 24-hour TS values obtained at 300 kg/m3 and 400 kg/m3 densities for 20 mm thick boards were obtained from 7%UF+3% P-MDI board group at 5.16% and 6.41%, respectively. The lowest 24-hour TS values obtained for 30 mm thick boards are 5.37% (300 kg/m3) with 7%ÜF+3% P-MDI and 5.68% (400 kg/m3) with 7%ÜF+2% P-MDI detected in board groups. When the mechanical properties of the board groups were examined, the highest BS and MOE values of 300kg/m3 density for raw boards were obtained as 0.88 N/mm2 and 378.04 N/mm2, respectively, in the use of 7% UF+3% P-MDI glue. In the 400kg/m3 density board groups, the highest BS and MOE were obtained as 2.03 N/mm2 and 286.72 N/mm2, respectively. The coating process on the board surfaces improved the mechanical properties, and the highest BS and MOE values were obtained with the coating of the board surfaces as 15.44 N/mm2 and 3905.63 N/mm2, respectively. The IB values increased with the increase in density, and the highest IB values were calculated as 0.14 N/mm2 for the board group produced at 400 kg/m3 density and 20 mm thickness and 0.18 N/mm2 for the 30 mm thickness. It has been determined that the mechanical properties decrease, but water absorption, thickness swelling, and insulation properties are improved with the increase in the use of bark in the boards produced by using 7%UF+3%P-MDI and wood bark mixture at different rates, which is determined as the best glue variation. The 24-hour TS value, which was calculated as 9% in the board group produced with 100% wood chips, was calculated as 7.48% in the board group with a bark chip mixture of 75% bark + 25% wood chips. The heat transmission coefficient values for the same board groups were measured as 0.07505 W/mK (100% wood chips) and 0.06648 W/mK (75% bark + 25% wood chips). With the use of vermiculite, a decrease in physical and mechanical properties was observed; It was determined that the mass loss at elevated temperatures decreased, and the thermal insulation properties were positively affected. Although the 24-hour thickness swelling value of 7.95% in the board group without vermiculite added (100% bark) increased with the addition of 15% vermiculite (8.16%), it was found that this value was lower than the 24-hour thickness swelling value (8.28%) of the board group produced with 100% wood chip without vermiculite addition. According to the results of the combustion test, weight losses of 16.7% for flame-caused combustion (FCC) and 19% for self-combustion (SC) were measured in the bark control group without vermiculite added, and it was found as 6% (FCC) and 9.8% (SC) with the addition of 15% vermiculite. The lowest heat transmission coefficient value of the bark insulation boards was 0.06360 W/mK in the boards produced with 4% P-MDI glue. For the coated boards, the lowest heat transfer coefficient value was obtained with 0.0671 W/mK and 3% P-MDI control group. It has been determined that the density of the board affects the heat transmission coefficient significantly; the heat transmission coefficient increases with the increase in the density. Therefore, increase in density of 100 kg/m3, the average increase in heat transmission coefficient was calculated as 0.012 W/mK for 20 mm thick boards, and 0.011 W/mK for 30 mm thickness. It was determined that the sound insulation property improved with the surface coating process and the increase in density. While the average sound transmission loss (STL) was 11.21 dB at 300 kg/m3 density and 17.02 dB at 400 kg/m3 density, it was calculated as 11.21 dB and 28.08 dB for uncoated and coated boards with the same thickness and density. When the results obtained in terms of the examined properties are evaluated, it is concluded that the insulation boards produced from black pine bark at specific densities can be used for heat and sound insulation purposes.