LOW-TEMPERATURE BONDING OF TIMBER STRUCTURES

Any bonding operation requires a tight control of environmental conditions (most importantly temperature and moisture) to ensure the desired mechanical performance during service life. To overcome these restrictions, the study shows how inductively heated Curie particles can be used to cure wood adhesives (epoxy and polyurethane) under low temperature conditions (+5 and –10 °C). The investigations were carried out using standardised specimens (dogbone / wooden lap shear joints) as well as large Glued-in Rods (GiR). The process is very well suited for the epoxy adhesive, which showed a mechanical performance equal to that of the references. In contrast, the technique is not applicable to polyurethane adhesives bonded on wooden adherends due to moisture diffusion, which interferes with the polymerisation – a problem, which might be solved by using a different particle type with lower Curie temperature, Tc.