Influence of interface/interphase on the dielectric properties of composites

Thermally stimulated current spectroscopy (TSC) has been applied to the study of interfaces/interphases in composites. Three DGEBA-DDA matrix model samples have been considered: matrix, matrix plus elastomer-coated glass beads, and matrix plus silane-treated glass beads. Below room temperature, the γ and β relaxations have been observed together with the mode associated with the glass transition of the elastomeric interphase that only represents less than 1% in weight of the composite. Above room temperature, a complex TSC α peak has been found with the same characteristics regardless of the nature of the interface/interphase in composites. However, the analysis of the fine structure of the α mode shows the existence of a compensation phenomenon characteristic of the matrix-filler interface/interphase. Surface treatment by silane decreases the number of accessible sites while the elastomeric coating increases the number of accessible configurations