Epoxy complex shear modulus

Dynamic and mechanical noperties of the epoxy resin powdered polystyrene (hardening with polyeth eneamine) have been examined. The average nze of the filler particles was SO p. The filter concoitiation varied from 5 to 50% by volume. The specimens were deformed accoiding to the harmonic law within tlte temperature range of 80 and 140 °C. In the experin ts the amplitudes of deformation and stress were changed and so was the phase an e between them, and tl ta were used to evaluate temperature dependences of the real part of the complex shift of shear modulus G of the filled specimens. Figure 26 illustrates the frequency dependence... 

A close look at the stress state indueed within this joint indicates clearly a complex interaction of strain, and there are many useful commentaries on the limitations of this test(4, 5. 25, 31). If the adherend and adhesive moduli are very different (e.g. the ratio of epoxy to steel moduli, E E = 40), the axial strains in the adhesive will be about 40 times greater than those in the adherend with a similar ratio for the lateral (Poisson s) strains. Where the two materials join, this conflict is resolved by generating large interfacial radial shear stresses (Fig. 4.11(c)). Joint strength inereases with a decrease in adhesive thickness, and in a thin bondline affected completely by adherend restraint a eomplex stress arises. The ratio of the applied stress to the strain across the adhesive is then defined as the apparent or constrained Young s modulus, a(5)-... 

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