Extensive work has been conducted to study the effect of the interphase on the mechanical behavior of particulate-epoxy composites and particulate-reinforced composites by dynamic mechanical testing. However, few studies have focused on the combination of controlled variation of interfacial structure and the effect of the moisture on the mechanical behavior of the composite materials.
In this investigation, dynamic mechanical analysis was used to study the effect of water on the properties of glass bead-epoxy composites with differing degrees of interfacial bonding. The effect of water was assessed by comparing the measured mechanical properties of dry and water-soaked specimens. The specimens types included plain epoxy matrix, composites made with clean glass beads, and composites made with glass beads treated with a silane coupling agent. The dynamic mechanical tests included temperature ramp tests, yielding spectra of storage modulus and loss tangent, and multifrequency tests, yielding master curves and apparent activation energies of molecular relaxation processes.
The theoretical background of the dynamic mechanical testing and calculation of the activation energies are reviewed. The results from related studies and their conclusions are also reviewed. Experimental procedures, including the chemical structures of the materials, the procedures for production of the glass bead-epoxy composites, characterization procedures, and the potential sources of the experimental error are described.