Rheological modelling of thermoset composite processing

Abstract

The rheological properties of epoxy matrices and adhesives during cure are modelled in this work. Three epoxy-amine systems, designed for different applications with distinct curing behaviours, were investigated. Curing times ranged from a few seconds to upwards of 220 min depending on the cure temperature and formulation of the epoxy. The presented time-dependent model adds an exponential fit to Kiuna-Fontana's master curve of dimensionless viscosity, as well as a weighting function for the overall fit, aiming at creating a more accurate model. A major benefit of the approach is that time consuming determination of the cure kinetics using differential scanning calorimetry (DSC) is not required. The developed model was also used to predict the viscosity of a typical, non-isothermal curing cycle for composite manufacturing. It proved to correlate well with both isothermal and non-isothermal processes, demonstrating that it is particularly useful model to describe viscosity for flow modelling or process optimisation.