Modeling the chemorheological behavior of epoxy/liquid aromatic diamine for resin transfer molding applications

Abstract

International audienceThe analysis of the chemorheological behavior of an epoxy prepolymer based on a diglycidylether of bisphenol-A (DGEBA) with a liquid aromatic diamine (DETDA 80) as a hardener was performed by combining the data obtained from Differential Scanning Calorimetry (DSC) with rheological measurements. The kinetics of the crosslinking reaction was analyzed at conventional injection temperatures varying from 100 to 150 degrees C as experienced during a Resin Transfer Molding (RTM) process. A phenomenological kinetic model able to describe the cure behavior of the DGEBA/DETDA 80 system during processing is proposed. Rheological properties of this low reactive epoxy system were also measured to follow the cure evolution at the same temperatures as the mold-filling process. An empirical model correlating the resin viscosity with temperature and the extent of reaction was obtained to carry out later a simulation of the RTM process and to prepare advanced composites. Predictions of the viscosity changes were found to be in good agreement with the experimental data at low extents of cure, i.e., in the period of time required for the mold-filling stage in RTM proces

Correlation analysis of epoxy/amine resin cure, structure and chemorheological behavior in RTM processes

“…At the same time, the mathematical modeling of resin curing kinetics and viscosity fitting for the mould‐filling stage has attracted considerable attention of engineers and scientists, and the curing kinetics and the resulting viscosity changes of various epoxy resin systems have been studied, always by means of differential scanning calorimetry (DSC) [12–14]. Lawrence et al [15] developed a new viscosity model of a two‐part epoxy/amine during the resin flow process, without the need for determining the resin curing kinetics.…”

Control of reactions and network structures of epoxy thermosets

“…Concurrently, the rate of the AM mechanism is proportional to the concentrations of alcohol and of activated monomer as indicated by Eq. (8). In this condition, the relative rate of the AM mechanism, ( )…”

“…For instance, several liquid composite molding techniques rely on the injection of the liquid formulations. Resin transfer molding (RTM) [8,9,83] involves the pumping of the liquid precursors into a heated mold cavity containing preplaced fiber materials. Reaction injection molding (RIM) [79,84,85] is based on the premixture of two or more liquid components at high pressure in a hydraulically operated mixhead, followed by the injection in the mold cavity.…”

“…However, it also requires a fine control of the viscosification kinetic that eventually comes with a transition from the liquid to the solid state: the gelation [5,6]. This is true, for obvious reasons, in the most common engineering processes including injection and molding [7][8][9][10]. It is also the case when solid fillers (e.g.…”

Phenoxy nanocomposite carriers for delivery of nanofillers in epoxy matrix for resin transfer molding (RTM)-manufactured composites

“…Higher TP fractions produce co-continuous or phase inverted morphologies, which yield even higher improvement of the fracture toughness since a crack must propagate through a continuous TP-rich phase. Nevertheless, the use of such high TP concentrations is prevented in many cases due to the decrease of other mechanical properties and due to the significantly reduced resistance to organic liquids [1][2][3][4][5][6][7][8][9][10][11][12][13].…”