Creep Behaviour and Testing of One-Component Polyurethanes and EPI Adhesives

摘要

The following reports on creep test methods and results of 30 test series with spruce specimens glued with moisture hardening one-component Polyurethane (1K-PU) adhesives and emulsion polymer Isocyanates (EPI) adhesives for structural timber components. All tests were performed according to EN 15416-3:2010, however with the glue line thickness differing in several cases from that stated in the standard as a result of changes from the previous version. The primary aim of the comparative evaluation consisted in the clarification of the effect of prolonged creep times on the ratio of creep between 1K-PU bonds vs. minimally creeping PRF-specimens. The investigations revealed that it is plausible to reduce the presently standardized creep periods of 26 and 52 weeks, down to 13 and 26 weeks respectively, in the case of 1K-PUs and for glue line thicknesses in the range of 0.1 mm to 0.5 mm. The results will serve as a basis for a change of the European test and requirement standards of 1K-PUs, EN 15416-3 and EN 15425.