Chemical/mechanical analyses of anhydride-cured thermosetting epoxys: DGEBA/NMA/BDMA

The chemical state of cure in a thermosetting resin was used to predict the resin's equilibrium modulus. High performance liquid chromatography analyses of the sol fraction yielded molar dynamics for monomeric, oligomeric, and polymeric molecules. Their population density distributions were compared with theoretical predictions based on a chain-growth polymerization mechanism. The resulting chemical estimates of the state of cure were integrated into calculations yielding concentrations of network structures within the gel that contribute to the density of elastically active strands and junctions. The theory of rubber elasticity was then used to predict the equilibrium modulus. Measurements incorporated dynamic mechanical analysis. A comprehensive understanding of the polymerization mechanism and cure history are required for accurate simulations of contributions from branch nodes and chain links. Deterministic models based solely on chemical reaction analysis were used to estimate chain connectivity with the gel. Results were interpreted using stochastic-based reasoning.