Experimental modeling of the cure behavior of a formulated blend of DGEBA epoxy and C12-C14 glycidyl ether as a reactive diluent

Abstract

Microwave curing of polymer matrix composites has been suggested as an attractive substitute for conventional thermal curing. Formulations of epoxy and reactive diluents have the advantage of better wettability and uniform fiber impregnation. However, higher peak exotherms in large masses, and thus thermal overshoot, presents a challenge for cure cycle optimization. Therefore, building a reliable curing model will not only predict the behavior of these materials during actual processing, but also facilitate numerical modeling of the process and comparison of other resin formulations. In this study the effect of the reactive diluent on the isothermal cure kinetics of low viscosity epoxy was investigated using differential scanning calorimetry (DSC). A formulated blend of diglycidyl ether of bisphenol A (DGEBA) and C 12 -C 14 aliphatic glycidyl was cured using diethylene triamine as the curing agent. Using a standardized procedure, ISO 113571-5, the epoxy formulation was isothermally cured at several temperatures and the heat flow monitored and recorded. Using the heat flow data from DSC, the rate of cure was determined experimentally and a proper autocatalytic model with a total order of about 2.3 was fit to describe the process. Leastsquare regression and isoconversion methods were used to find the model parameters and the activation energy, respectively. The accuracy of the model shows fine correlation with experimental data. By comparison to other epoxy resin without diluents, the analysis of the data shows that the reactive diluent increased the curing rate, while the values of activation energy and process parameters remained within the typical values of epoxy formulations. Based on these data, the future use of these types of resins in nonthermal curing of epoxy matrix composites is discussed. POLYM. COMPOS., 26: 593-603, 2005.

Morphology and thermal and dielectric behavior of cycloaliphatic epoxy/trimethacrylate interpenetrating polymer networks for vacuum‐pressure‐impregnation electrical insulation

“…During the past decade, a number of diagnostic techniques have been developed to evaluate the crosslinking degree of epoxy resins, including infrared spectroscopy, 14 differential scanning calorimetry, 15 and viscosity. 17 All of these techniques not only require well-equipped laboratory conditions and the destruction of the samples used but also are usually complex and costly to implement.…”

“…With the development of the electrical industry, the requirements of the properties of VPI resins has become higher and higher, and much effort has been devoted to the modification of the mechanical, thermal, and electrical properties of epoxy resin. [5][6][7][8][9][10][11][12][13][14][15] One new type of VPI resin, which contains in situ sequential interpenetrating polymer networks (sIPNs) resulting from the curing of cycloaliphatic epoxy resin (CER) and trimethacrylate monomer [trimethylol-1,1,1-propane trimethacrylate (TMPTMA)], with more excellent properties than conventional VPI resins was developed in our previous study. 16 The macroscopic properties of polymeric materials are strongly dependent on their microstructures, which can lead the crosslinking structure of an epoxy resin to influence its physical, chemical, thermal, electrical, and mechanical properties.…”

Master curve and time–temperature–transformation cure diagram of a polyfunctional epoxy acrylic resin

“…This value was in agreement with that obtained from the t gel measurements (as is described later) and also with other bifunctional epoxy resin systems. Wisanrakkit and Gillham26 determined an E a value of 63.5 kJ/mol for systems based on diglycidyl ether of bisphenol A (DGEBA) and bifunctional amines; when DGEBA was used with diethylenetriamine, values between 56 and 59 kJ/mol were found 18, 27–30. Previously, Kissinger31 determined an E a value of 51.8 kJ/mol for the same reaction.…”

Study of glycidyl ether as a new kind of modifier for urea‐formaldehyde wood adhesives

“…[22][23][24] The commercially available GE are generally multifunctional chemicals containing optional numbers of epoxy rings attached by different length of ether linkages. Leon et al,25 reported that the epoxy ring of GE initial reacts with amine.…”

“…Glycidyl ether (GE) is a widely known reactive diluent and has been used in many applications, especially in epoxy adhesives 22–24. The commercially available GE are generally multifunctional chemicals containing optional numbers of epoxy rings attached by different length of ether linkages.…”