Degree of Cure, Heat of Reaction, and Viscosity of 8552 and 977-3 HM Epoxy Resin

The heat of reaction for the cure, degree of cure, and viscosity of Hexcel 8552, and Cytec Fiberite 977-3 HM neat resins were measured using a modulated differential scanning calorimeter (MDSC) and a rheometric digital analyzer (RDA). Expressions were developed using isothermal tests for correlating the rate of degree of cure and the viscosity with the degree of cure using a Lee, Loos, and Springer approach. The models were used to predict the kinetic behavior of the resins using the respective manufacturer s cure cycle. Data were collected and a good correlation was found with the model. In addition, the kinetic behaviors of these systems were compared to Hercules 3501-6 data. A second study was also performed to compare cure models developed based on neat and prepreg forms of the resin viscosity data. Vastly different viscosity behaviors were found indicating further physical insights are necessary to account for fiber/resin content and material properties difference.