Chemorheological behaviors of TDE-85 toughened by low viscosity liquid epoxy for RTM process

Abstract

In this study, 1,4-cyclohexanedimethanol diglycidyl ether (EP-1) has been synthesized via a two-step process to toughen and lower the viscosity of TDE-85 epoxy first time and suitable for the resin transfer molding (RTM) process. Chemical structure of EP-1 and the reactivity, rheological and mechanical properties of TDE-85/MeTHPA/DMP-30/EP-1 system were studied. When the composition ratio of TDE-85/MeTHPA/EP-1/DMP-30 is 100: 140: 15: 1 and the curing process is 80 °C/2 h + 110 °C/2 h + 140 °C/2 h, the overall performance of the resin system reached to an optimal value. Impact and bending strength of the casting came out to be 27.64 kJ m−2 and 167.2 MPa, which improved 75.16% and 17.50% respectively compared to the pristine resin system without EP-1. Dynamic viscosity analysis of TDE-85/MeTHPA/DMP-30/EP-1 system showed that the viscosity-temperature curve was U-shaped and the platform zone was located around 60–95 °C during which the viscosity was less than 200 mPa s. Dual-Arrhenius and engineering viscosity models were established to predict the viscosity characteristics of the resin. It was found that the dual-Arrhenius model matched better with the experimental data at low temperature and low viscosity region. Whereas when the viscosity increased, the engineering viscosity model became more accurate. The viscosity analysis provided the basis for the window prediction of RTM molding process.