Thermal properties and volume fraction of the boundary interphase in metal-filled epoxies

Abstract

A previous study (1) on the thermomechanical behaviour of metal-filled Epoxies led us to conclude that the concept of the boundary interphase is a very useful tool for describing quantitatively the quality of adhesion between the matrix and the filler particles. It was shown that this interphase exists in reality and is an area between filler and matrix, which contains both areas of adsorption interaction in polymer surface layers into filler particles, as well as an area of mechanical imperfections. In the present paper, under the assumption that the interphase is homogeneous and isotropic, exhibiting perfect adhesion with both main phases, a theory was developed to describe the thermomechanical behaviour of this interphase. Thermal expansion coefficients and volume fraction of the interphase of a large number of composites were determined and the effect of various parameters, such as temperature, volume fraction of filler and particle size, were examined for specimens exhibiting imperfect as well as perfect adhesion between matrix and filler.