Cure Modelling and Monitoring for Isothermal Processing of Fast-Curing Epoxy Resin

"In liquid composite moulding processes, the curing behaviour of thermoset matrices
plays a decisive role in determining manufacturing quality and cycle time. Premature
demoulding may lead to insufficiently cured components, whereas excessively long curing
times reduce production efficiency. Reliable monitoring and modelling of the curing process
are therefore essential for process optimisation. In this study, the cure kinetics of a fast-
curing epoxy resin system are modelled using the Grindling kinetic model, which accounts
for diffusion-controlled reaction behaviour and vitrification effects. Model parameters
are identified using both dynamic and isothermal differential scanning calorimetry (DSC)
measurements. In addition, the glass transition temperature is described as a function of the
degree of cure using the DiBenedetto relationship. To demonstrate the applicability of the
model for process monitoring, an experimental mould equipped with temperature sensors
was developed to simulate real-time estimation of the degree of cure during isothermal
processing. The predicted degree of cure is validated by post-process DSC analysis of
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the manufactured samples. Initial comparisons reveal systematic deviations caused by
temperature measurement uncertainties. After implementing a temperature correction
based on experimentally determined sensor deviations, the predicted degree of cure shows
significantly improved agreement with DSC measurements. The results demonstrate
that combining kinetic modelling with temperature monitoring enables reliable real-time
estimation of the curing state for fast-curing epoxy systems. The study also highlights
the critical importance of accurate temperature measurement for curing monitoring and
provides insights into the practical implementation of sensor-based monitoring strategies
in liquid composite moulding processes"