Prediction of processing windows for low viscosity epoxy resin system used in RTM

Abstract:

In order to efficiently predict the rheological viscosity of low viscosity epoxy resin TQ-50 and determine suitable processing window in resin transfer molding (RTM) process, the properties of TQ-50 resin system including curing reaction characteristics, static viscosity, dynamic viscosity, and gel time were systematically investigated by using differential scanning calorimetry (DSC), viscometer, rheometer, and gel time tester. Based on the experimental results, the static rheological model of TQ-50 was established by using Arrhenius equation. It was found that the rheological model was well consistent with the experimental results and could accurately describe the chemical rheological behavior of TQ-50 in low viscosity range. On the basis of the rheological model, three-dimensional prediction maps of temperature, time, and viscosity as well as viscosity curves of temperature and time were established, and the processing window was predicted, which provided guidance for the optimization of process parameters. Results show that when the viscosity was lower than 500 mPa·s, the optional processing window temperature was 50~70 ℃, and the holding time was about 150~180 min. When the viscosity was lower than 200 mPa·s, the optional range window temperature was 55~70 ℃, and the holding time was about 56~96 min. The resin system has a wider range of suitable injection temperature and longer injection time, which can meet the basic requirements of RTM processing.