Fully Bio-Based Wood Adhesives with Reversible Bonding from Epoxidized Plant Oils

High Resolution Image Download MS PowerPoint Slide This study presents a comprehensive investigation into fully renewable wood adhesives based on epoxidized linseed oil (ELO) cross-linked with bioderived carboxylic acids─citric, tartaric, and sebacic acid. Reactivity and successful curing of the prepared adhesive mixtures were confirmed using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Comparative performance in terms of dry strength and wet strength was tested using an Automated Bonding Evaluation System (ABES). Among the tested systems, ELO–citric acid (ELO-CA) showed the best combination of curing reactivity, mechanical strength, and water resistance with 8.2 and 6.3 MPa of mean dry shear strength and mean wet shear strength, respectively. Curing temperature and time of the ELO-CA system were optimized based on DSC with kinetic modeling as well as ABES tests with glued veneer samples, which showed that curing can be achieved within minutes at elevated temperatures. Lap shear tests (160 °C, 30 min; 0.8 MPa; 250 g/m 2 ) reproduced the ABES performance, achieving 8.4 MPa (dry) and 7.9 MPa (wet), whereas slower curing at 120 °C promoted overpenetration and poor wet strength. Reheating fully cured ELO-CA bonds of veneers to 160 °C for 5 min reduced shear strength from 8.2 to 1.6 MPa, enabling damage-free debonding. This reversible bonding is driven by transesterification of the covalent adaptable ester network (CAN) and/or softening above T g . This first in-depth investigation of ELO-based wood adhesives positions these fully renewable formulations as interesting candidates for wood bonding, combining strong dry and wet performance with the potential for recyclability.