DYNAMIC-MECHANICAL PROPERTIES OF EPOXY-RESIN EPOXIDIZED RUBBER BLENDS- EFFECT OF PHASE-SEPARATED RUBBER

The dynamic mechanical properties of blends of diglycidyl ether of bis phenol-A-based epoxy resin and internally epoxidized polybutadiene rub ber have been studied. It is shown that the influence of the compositi on of the continuous phase and of the dispersed phase can be studied n ot only from the variations of the glass transition temperature but al so from the changes in the apparent enthalpy of activation associated with this transition. As the initial rubber content increases, the com position of the dispersed phase remains practically constant while mor e rubber is able to dissolve in the continuous phase. Analysis of the rubbery plateau region reveals that the shear modulus of the blends is not much affected by the presence of dissolved rubber in the continuo us phase but strongly depends on the volume fraction of dispersed phas e. This volume fraction can be obtained from the relative drop in shea r modulus after modeling the results with the Kerner equation. The res ults compares well with independent measurements by scanning electron microscopy. (C) 1994 John Wiley & Sons, Inc.