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Using a dynamic scaling theory for the viscoelasticity of cross-linking polymers near the gel point, we predict the superposition of viscoelastic functions at differing extents of reactions. For example, to superpose the stress relaxation modulus, a vertical shift is needed to account for the increase in the equilibrium modulus with cure, G" ~e8/3, and a horizontal shift for the divergence of the characteristic relaxation time, ~e~4, where < is the critical extent of reaction. Experiments on model epoxies show excellent superposition both below and above the gel point and give G" ~e2-8±0•2 and rz ~c~3'9±0•2. The critical regime where this superposition is valid is surprisingly wide, encompassing over half of the reaction.

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