Bond performance development of lab-scale oriented strand lumber panels with pressing time and its comparison with ABES results

A small-scale test for evaluating the cohesive strength development of adhesives, such as ASTM D7998-15, using the Automated Bonding Evaluation System (ABES), is often used in the development of wood-based panels and their adhesives. However, ABES results are not always directly transferable to panel performance, which may be particularly challenging for isocyanate adhesives, whose curing depends on moisture. Therefore, pine oriented strand lumber (OSL) panels were produced at different pressing times, analogous to bond-strength development measurements using ABES. Panels were tested for internal bond strength (IB), thickness swelling (TS), and water absorption (WA) to assess whether ABES trends are reflected in panel performance development. ABES data for the same adhesive–wood combinations were taken from our previous work and were also used as input for Virtual Hot Press (VHP) simulations. IB development in panels correlated with ABES during the strength-development phase, indicating that ABES is a useful tool for assessing relative curing speed. The kinetic ranking agreed, with modified methylene diphenyl diisocyanate (modified MDI) being the fastest, polymeric MDI (pMDI) and melamine–urea–formaldehyde (MUF1) intermediate, and MUF2 the slowest. In contrast, plateau strengths showed weaker agreement between ABES and panels, indicating that ABES is less reliable for predicting final IB. TS and WA were not suitable indicators of curing degree, whereas panel thickness after pressing provided a clearer indication of reaching maximum IB. VHP simulations captured overall trends but showed discrepancies due to uncertainty in the temperature input and predicted disproportionately longer press times for thicker and denser panels.