Joint strength mechanical interlocking contribution

It should be remembered, however, that there is evidence for chemical bonding at some interfaces and that, in general, mechanical interlocking is frequently assumed to make a contribution to joint strength. In these cases, predictions based on thermodynamic considerations will no longer be reliable. Also, such considerations give no indication of the expected service life of the bond in a hostile environment the thermodynamics enables a prediction to be made about the eventual outcome, but gives no indication of the kinetics of the processes involved. 

Notwithstanding the above comments, there is much work to be found in the literature which convincingly demonstrates that increasing the surface roughness of the substrate may increase the measured strength of the adhesive joint. The important question that must be asked is does such an observation arise from a contribution from mechanical interlocking to the intrinsic strength of the interface, or from other causes ... 

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