Effects of size and type of raw material on temperature and vapour pressure behaviour of wood-based panels during hot-pressing

This study investigated the effects of the size of various raw materials on the temperature and vapour pressure behaviour of wood-based panels during hot-pressing. Five types of materials (veneer, strand, particle, fibre, powder) were used as furnish and twelve different kinds of furnish were used for laboratory-scale wood-based composite panels. A press monitoring system (PressMAN Lite) was used for detecting the temperature and vapour pressure change in the centre of the mat panels. Results showed that the bulk density strongly relates to the size element. The highest bulk density was found in powder (sawdust, spruce) and particle (Hinoki blocks, Hinoki cubes, recycled wood). The uniform distribution of density strongly relates to the size of raw materials and in-plane density distribution could be an indicator for vapour pressure behaviour. The maximum vapour pressure corresponded to the plateau temperature for the mat-formed panels. The vapour pressure of the veneer was low even though the plateau temperature was high. The value of plateau temperature became higher in the order of particle, fibre, powder, and strand. The temperature behaviour of the veneer was different from that of mat-formed panels.