Computer Simulations of Epoxy Adhesive Monomer Interactions with Alumina Surfaces

An ongoing program in our laboratory seeks to elucidate the effect of aluminum oxide on the cure chemistry of epoxy adhesives. The project includes the use of molecular dynamics (MD) techniques to carry out real time simulations of the interaction of various epoxy adhesive monomers with idealized alumina surfaces. Adhesive monomers investigated include the diglycidyl ether of bisphenol A (DGEBA), a brominated form of DGEBA, diaminodiphenyl sulfone (DDS) and methylene dianiline (MDA). Both crystalline and amorphous forms of alumina at different levels of hydration have been simulated. The simulations illustrate the preferred orientations of the organic molecules with respect to the alumina surfaces and suggest which functional groups are most influential in determining this orientation. The model and experimental systems correlate well, showing similar response to changes in organic molecular structure, alumina morphology, and level of hydration. Model studies of this type can aid the understanding of the critical interphase region of adhesive bonds, including factors which affect bond durability, and have the potential to be used in the design of improved adhesives. Original contains color plates: All DTIC and NTIS reproductions will be in black and white.