Modeling of Chemorheology of an Amine-Epoxy System of the Type Used in Advanced Composites

A chemorheological study of an epoxy formulation consisting of tetraglycidyldiamino diphenylmethane (TGDDM) and diaminodiphenylsulfone (DDS) was carried out. An autocatalytic kinetic model with parameters acquired through differential scanning calorimetry (DSC) was obtained. Experimental viscosity data were collected as a function of time and temperature and used to develop two fundamental viscosity models: one based on the branching theory of polycondensation polymers and the other based on the free volume concept using a modified form of the classical WLF equation. The kinetic results were incorporated into the viscosity models and the experimental results checked against the model predictions. The branching theory model provided excellent agreement with both isothermal and non-isothermal viscosity data. The modified WLF model adequately predicted the isothermal viscosity data, but limitations in the model arose in predicting the non-isothermal viscosity.