Determination of adhesion strength between a coated particle and polymer matrix

The aim of the paper is to provide the theoretical basis for a test to determine the interfacial adhesion strength between a coated particle and a polymer matrix material. The specimen has a notched (neck-like) geometry and contains a single coated particle in the centre. A non-linear relation between the true stress and logarithmic strain is considered for the interphase. Tensile axial loading of such a necked sample concentrates stresses in the smallest cross-section and causes a multiaxial loading situation in the centre of the specimen, i.e., in the vicinity of the enclosed particle. By variation of sample curvature the distribution of normal tensile stresses at the interface between particle and coating can be changed. This enables the variation of the interface area which is under tensile stress. A finite-element analysis provides the stress field within the whole specimen and especially in the vicinity of the coated particle. The motivation for the calculations is to determine the maximum radial stress at the particle surface as a function of applied load. Assuming that normal stresses at the interface are responsible for debonding, the adhesion strength can be obtained from the experimentally determined critical load at debonding initiation.