THERMOSTIMULATED CREEP STUDY OF THE ALPHA RETARDATION MODE IN EPOXY-GLASS BEADS COMPOSITES

Thermo-stimulated creep (TSCr) analysis was performed to characterize the anelastic properties around the glass transition of the model system: epoxy resin-glass beads. Different interphase regions have been deliberately formed by means of a silane coupling agent and an elastomeric adduct coating. In all samples the primary retardation mode, labeled alpha, has been found around 140-degrees-C. This retardation mode has been associated with the anelastic manifestation of the glass transition of epoxy resin. The relative magnitude of this mode in filled epoxy has been used to estimate the interphase thickness. By applying ''fractional stresses'' the complex alpha peak has been experimentally resolved and local changes of morphology in the interphase zone are evidenced in terms of mobility and kinetic of motion. This last technique has also allowed us to compare the length of the mobile units liberated at the glass transition as a function of the filler-matrix interphase.