Water absorption and degradation in adhesive joints

grantor: University of TorontoTo assess the durability of adhesive joints, blistering as a form of degradation and water diffusion in adhesive joints were investigated. In addition, secondary bond effects on the measurement of critical strain energy release rate were examined to validate the open-faced specimen technique, and the degradation parameter was studied in greater detail. It was found that open-faced specimens can be used to test the fracture strength of the primary-bond with the secondary bonds having an insignificant effect. The degradation parameter concept requires further evaluation with other adhesives over longer exposure periods. It was also concluded that adhesive layers in closed joints cured at elevated temperatures have water diffusion coefficients and equilibrium water concentrations greater than those of the bulk adhesive. However, water absorption in closed joints can be predicted using Fick's law with the diffusion properties of the closed joints. Finally, it has been shown that blistering due to osmotic pressure is a form of degradation in joints exposed to high relative humidities.M.A.Sc