この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。In order to predict the service life of plywood heating floors, dry-heat exposure test of lauan plywood made with each of six type of typical wood adhesives was carried out at 50°, 70°, 100° and 150℃ for 250 days. Internal bond strength and location of failure of the exposed specimens were measured at selected intervals. Data were plotted as a function of the exposed time. Confidence limit was applied on the regression and the service life was calculated by extraporating the lower confidence limit curve to the half-strength. The apparent mechanism of dry-heat degradation of plywood in 150° and 100℃ seemed to differ from the lower temperature exposures. On 70° and 50℃, more conservative estimation was made by the kinetic method on the Arrhenius relationship. The result showed the detrimental effect of the acid catalyst on polyvinyl-acetate cross-linked and urea resin adhesives. Plywood specimens produced with melamine, phenol, phenol-resorcinol, and resorcinol resin adhesives showed excellent durability in dry-heat exposure at temperature normally found in service of floor heating
