Continuum and Fracture Mechanical Studies of Contaminated Bonding Surfaces

The importance of fracture mechanics testing of contaminated bonding surfaces is discussed. The sensitivity of adhesive bond systems to contamination may increase dramatically when macroscopic cracks are present. A bond system is shown to retain a significant level of tensile adhesion strength at relatively high levels of contamination, yet have near zero mode I fracture toughness at very low levels of the same contaminant. Silane adhesion promoter is shown to reduce greatly the system fracture toughness sensitivity to contamination, especially at lower levels of contamination.