Long-Term Development of Thermophysical and Mechanical Properties of Cold-Curing Structural Adhesives Due to Post-Curing

The long-term changes in the thermophysical and mechanical properties of a cold-curing structural epoxy adhesive were investigated by accelerating the curing reaction by post-curing at elevated temperatures. Experimental data concerning the glass transition temperature for periods of up to 7 years and tensile strength and stiffness measurements could be extrapolated for a period of up to 17 years. An existing model for the long-term development of concrete properties was modified for the prediction of the long-term mechanical properties of adhesives. The applicability of the acceleration procedure and the new model was confirmed by several verification procedures. Structural adhesives exhibit significant increases in glass transition temperature, strength and stiffness over the long term provided that joints are adequately sealed and protected from humidity and UV radiation. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2490-2496, 201