Changes in Characteristics of Wood Fiber Insulation Board According to Density

As the demand increases for low energy green buildings, such as passive housing, the development of new insulation systems based on natural materials is underway. In this study, 20-mm-thick wood fiber insulation board (WIB) samples of different densities were prepared using melamine-formaldehyde-urea (MFU) resin adhesives. The resin contents were fixed at 35% and the target densities were 0.10 g/cm(3), 0.15 g/cm(3), 0.20 g/cm(3), and 0.25 g/cm(3). The thermal conductivities of the WIBs gradually increased as the density increased. The formaldehyde (HCHO) emissions of all the WIBs indicated that they were of "Super E-0" (SE0) grade, but the quantity of the HCHO emissions slightly increased as the density increased. The thickness swelling of all the WIBs was stable at less than 3%, and the bending strength linearly increased as the WIB density increased. A notable decrease in the water absorption rate was observed between the lower and higher density WIB samples. Based on the results of the cone calorimeter tests, the carbonization depth ratio and the weight loss rate remarkably decreased as the density increased. Therefore, the optimum WIB density was in the range of 0.15 g/cm(3) to 0.20 g/cm(3) to provide adequate insulation performance as well as human and structural safety.