Veränderung der Wasseraufnahme und der Rohdichteprofile von mit PF-Harz und PMDI hergestellten MDF bei Wasserlagerung

PF- and PMDI-bonded laboratory made fibreboards (binder content 10% PF-resin and 6% PMDI) were stored under water at different temperatures (40°C, 50°C and 60°C) for a period of six weeks. The water absorption of the boards was measured, moreover the change in density profile was also registered for boards stored at 40°C after drying at 40°C and climatisation at 20°C and 65% relative humidity. The results show that at the beginning of storage time PF-bonded boards absorb relatively more water than PMDI-boards. Thereafter, the water uptake of PF-boards increases at a lower rate compared to PMDI-boards. The density profiles reveal that the major change in density due to water-storage is mainly in the middle layers of the boards