One-component polyurethane adhesives for green wood gluing: Structure and temperature-dependent creep



Creep and temperature-dependent creep, characteristic of one-component polyurethane adhesives for wet and green structural wood gluing are two different parameters. Testing of standards-approved commercial polyurethane adhesives for this purpose shows that while ambient temperature creep can be avoided or at least greatly limited according to the formulation used, this is not the case for temperature-dependent creep. The commercial adhesive formulation characteristics that minimize or enhance ambient temperature and temperature-dependent creep are identified. Basic principles on the structure of simple polyurethane adhesives influencing temperature-dependent creep are also identified and discussed. The higher the proportion of all hardened network nodes, the lower creep is likely to be at ambient temperature. Instead, due to segment movement and easier disentanglement with increasing temperature, the lower the proportion of covalently linked nodes and the greater the proportion of just physical entanglement nodes, the greater the temperature-dependent creep will be. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1231–1243, 2005