Characterization of fast‐cure resins for reaction injection molding

The interest in reaction injection molding of urethane and non‐urethane resins has generated a need for a greater understanding of the molding behavior of these reactive systems. The kinetics and rheology of a given resin must therefore be well characterized in order to understand and model the molding process. This often requires semi‐empirical correlations rather than strict theoretical considerations. A method of fully characterizing such systems by combining adiabatic reactor and IR studies with viscometer data is therefore described. This results in time‐temperature‐conversion‐viscosity correlations which can be directly utilized in molding studies. Such methods are applied to polyurethane and epoxy systems in the work presented here. It was found that very different activation energies are obtained for the same epoxy‐amine system using different kinetic characterization techniques.