ABSTRACT
In this work, we consider the results of experimental and modeling approaches to demonstrate the beneficial effects of silanes on delamination rates of elastomermetal (steel) adhesive bonds.
On the modeling front, we consider two different models capable of predicting the rate of delamination for elastomer-metal adhesive bonds upon exposure to cathodic conditions. In [1], an empirical model which relates cathodic bond delamination rate to strain energy release rate, G, was introduced. Later, a semi-empirical model based on physical considerations of the delamination problem was introduced in [2] which, in turn, was based on previous work [3] that dealt with the semi-empirical modeling of the cathodic weakening (stress-free) mode of bonded joints and where weakening rates were mathematically related to the harshness of the environment. (A weakened bond appears to be intact, but if physically separated the bondline would be revealed to have been degraded.) In [3], it was determined
that given an electrolyte, cathodic weakening rates depend heavily on temperature and cathodic voltage (current density). If cleavage stresses act upon a weakened bond, then a complete and visible separation of the bonded constituents occurs, resulting in the form of bond degradation commonly referred to as delamination [4]. In addition to the weakening formulation, the delamination formulation in [2] incorporates an additional expression to account for delamination mode (i.e., stress effects through the stress parameter of strain energy release rate or G). Delamination rates are found to be influenced by the same environmental parameters that affect weakening rates. In addition, the magnitude of the peel stress was found to play a significant role as well.
