EVOLUTION OF STRUCTURE AND VISCOELASTICITY IN AN EPOXY NEAR THE SOL-GEL TRANSITION

The divergences of the average molecular weight, average cluster size, and bulk viscosity as the gel point is approached and the power law behavior of the dynamic shear moduli at the gel point were measured for a cross-linked epoxy. The critical exponents describing the evolution of static structure were found to be significantly different from the predictions of mean-field theory and in reasonable agreement with percolation. The exponents describing the viscoelastic behavior in the critical region were found to be significantly different from the predictions of the de Gennes electrical analogy and in good agreement with our scaling theory. © 1990, American Chemical Society. All rights reserved.