Dynamic mechanical analysis (DMA) has been used to investigate the effect of water and
glass bead surface treatment on the properties of glass bead-epoxy composites. By treating
or not treating the glass beads with a silane coupling agent, we fabricated composites with
ostensibly good or poor interfacial adhesion. SEM images of fracture surfaces and water
uptake data confirmed this picture. We used dynamic mechanical tests to measure the
material properties of dry and wet specimens. Temperature sweep tests of atmosphereconditioned
specimens indicated that the value of the loss tangent at the temperature of
the a-relaxation peak was most sensitive to interfacial adhesion. For wet specimens, the
magnitude of an additional relaxation process, denoted as the w-relaxation, correlated
strongly with water uptake and, indirectly, interfacial adhesion. Master curves constructed
from frequency sweep tests also manifested differences among dry and wet specimens, but
shift factor data suggested that these tests were more prone to complications due to water
loss. Apparent activation energies of a- and @-relaxation processes were statistically significant
indicators of interfacial adhesion in dry and wet composites, respectively