Effect of face-layer moisture content and face–core–face ratio of mats on the temperature and vapor pressure behavior during hot-pressing of wood-based panel manufacturing

Abstract

Wood-based panels are made by consolidating mats of resinous wooden raw materials under a hot-pressing process. This study investigates the effect of face-layer moisture content (MC) and face–core–face (FCF) ratio of mats on the temperature and vapor pressure behavior during the hot-pressing process. Raising the face-layer MC and lowering the face-layer thickness was expected to reduce the time of reaching 100 °C in the hot-pressing process. When the temperature rise was limited or the core temperature decreased after reaching 100 °C (defined as plateau in this study), the mats with 25% and 30% face-layer MC with 1:2:1 FCF ratio reached the highest plateau core temperature, but required a longer time to complete the plateau. The relationship between core plateau temperature and maximum core vapor pressure was well described by the Antoine equation, which empirically models the vapor pressure as a function of temperature. The Antoine equation held across both face-layer MC series (varying face-layer MC at constant FCF ratio) and FCF series (varying FCF ratio at constant face-layer MC). The mat with 20% face-layer MC and 1:2:1 FCF ratio reached 180 °C within the shortest time, regardless of the evaluation conditions.

Changes in Temperature and Vapor-Pressure Behavior of Bamboo Scrimber in Response to Hot-Pressing Parameters

“…Consequently, water vapor in the core layer encountered obstacles in smooth discharge, leading to a continuous increase in water-vapor pressure. This transformation evolved from a saturated-steam state to a superheated-steam state [30,35]. Additionally, at the same hot-pressing temperature, the horizontal temperature distribution both in the surface layer and core layer was uneven.…”

“…The phenomenon was attributable to the reduced porosity inside the BBSs at higher hot-pressing pressure. Furthermore, based on the ideal gas law, the vapor pressure inside the slab increased significantly when the hot-pressing temperature was unchanged, decreasing the pore volume [30,35]. Additionally, the premature compaction of the slab under the high hot-pressing loading made it difficult for vapor to escape from the BBS during the hot-pressing process.…”

The mechanism of moisture transport and mechanical model of ultra- thin fiberboard

“…The hot pressing process involves heat and mass transfer, interfacial infiltration of the adhesive, chemical reaction and physical adsorption, compression rheology of the fibers, elastic-plastic deformation, hydrothermal degradation, plasticization, shaping, and so on. There will be differences due to various factors such as the type of adhesive (Wang et al 2022), the shape and type of fiber (Xing et al 2006; Mohebby et al 2008;Murayama et al 2021), the hot pressing process conditions (Rofii et al 2014; Gonçalves et al 2020), and the hot pressing method (Mendes et al 2013). Due to the complexity of the hot pressing process, it's not easy to quantitatively analyze the effect of hot pressing process parameters on fiberboard properties.…”

Characteristics of the Pressing Process and Density Profile of MUPF-Bonded Particleboards Produced from Waste Plywood

“…It is generally assumed that it should not be less than 85%. The relationships between the course of the pressing operation and the density profile of the particleboards constitute the basis for the analysis of phenomena shaping the physical and mechanical properties of particleboards [25,26]. The problem of using recycled particles in the production of particleboards is rarely analyzed.…”