Film Thickness Effects on Interfacial Fracture of Epoxy Bonds

Abstract

Nanoindentation test techniques were combined with deposition of highly stressed overlayers to study the interfacial fracture susceptibility of spin coated Epon 828/T403 on aluminized glass substrates as a function of film thickness. The test techniques required to induce fracture differed between samples. Nevertheless, the resulting interfacial fracture energies decreased monotonically with film thickness to a value near 0.5 J/m 2 . This value is higher than the 'true work of adhesion' for uncured epoxy oliogomers on a methyl-terminated aluminum surface. However, it may indicate that we have irreversible specific interactions such as hydrogen bonding. Then 0.5 J/m 2 may be near the fundamental value for such an interaction, or the 'practical work of adhesion'.