SYNOPSISThe mechanical properties of a hollow glass microsphere-filled epoxy resin composite system were investigated in air as a function of the weight content of particles ranging from 0 to 15.38% (wt/wt). The analysis based on necessarily modified classical models together with structural observations enabled explanation of the composition dependencies of elastic moduli of the blends studied. It was found that, together with a presumption of no interfacial adhesion between the filler and matrix, an interlayer of immobilized matrix with changed mechanical properties compared to the formal matrix seems to strongly affect the mechanical behavior of the composite. and the debonded microsphere.

The morphology of a syntactic foam (hollow microspheres in a polymeric matrix) is differently affected when cured in thermal and microwave fields. The microwave curing energy excludes heat conduction and due to faster energy transfer more efficient crosslinking effects are observed at the interface, leading to a higher internodular crosslink density at the particle interface. As a consequence, slight but observable differences of mechanical behavior arise when curing the hollow glass microsphere filled epoxy resin composites in thermal and microwave fields. The observed differences probably imply different mechanisms of failure at the particle‐matrix interface.

After some recalls on the dielectric behavior of the organic materials, a parametrical study of the activation by continuous microwaves (2 450 MHz) of the curing reaction of an epoxy resin of DGEBA type in presence of diamino‐biphenyl‐methane used as crosslinking agent, is carefully described. The recording during the irradiation of the variations of the average temperature of the chemical medium and of the associated dielectric loss on the one hand, and the determination of the glassy transition temperature of the final networks on the other hand, allows optimization procedures of the electromagnetic treatment of the initial prepolymeric mixtures.

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The Young's moduli of composites made up to 51.5% by volume of hollow glass spheres in an epoxy resin matrix have been measured. The data have been compared with the calculated elastic moduli of a composite where the filler particles act as holes (Sato-Furukawa model). The discrepancy arises from the neglect of particle-matrix interfacial effects.