Blends of epoxy/anhydride thermosets with a high-molar-mass poly(methyl methacrylate)

In this study, the physical and chemical changes of a poly(methyl methacrylate) (PMMA)-modified epoxy system were examined to understand the effect of the curing conditions on its final morphology. The curing process of the PMMA-epoxy reactive system was complementarily analyzed by Fourier transform infrared spectroscopy in the near range (FT-NIR) and fluorescence spectroscopy. The relationships among (1) the chemical conversion of the curing reaction, (2) the first moment of the fluorescence emission band (hmi) arising from a chromophore chemically bonded to the epoxy reactive system, (3) the phase-separation process, and (4) the dynamics of the epoxy thermoset during its curing process are discussed. From a chemical point of view, FT-NIR did not reveal any significant change in the curing reaction with the presence of 2 wt % PMMA. However, in terms of physical changes, the analysis of the fluorescence response clearly showed variations in the curing reaction due to the presence of the thermoplastic polymer. Also, fluorescence allowed the estimation of the glass-transition temperature of the system with curing when the reaction was diffusioncontrolled, whereas Fourier transform infrared spectroscopy was not sensible enough. In the second part of this study, scanning electron microscopy images of the PMMAmodified epoxy system were analyzed to understand the effect of the temperature on the final morphology when the amount of thermoplastic was below the critical volume fraction. A linear dependence between the inverse of the mean area of the thermoplastic-rich domains and the inverse of the absolute temperature was obtained.

Section: Resultsmentioning

confidence: 99%

Phase‐separation process in a poly(methyl methacrylate)‐modified epoxy system: A novel approach to understanding the effect of the curing temperature on the final morphology

Olmos

Loayza

González‐Benito

2010

“…As a part of a series of studies on the modification of epoxy resins in this laboratory,14–20 this work concerns the investigation of bifunctional epoxy–PSu blends and the effects of differences in the reaction kinetics of epoxy–amine, the cure temperature, and the blend composition on the morphologies generated.…”

Section: Introductionmentioning

confidence: 99%

Morphology control in polysulfone‐modified epoxy resins by demixing behavior

Giannotti

Solsona

Galante

et al. 2003

Polysulfone (PSu) was used as a modifier of epoxy/aromatic diamine formulations. Two epoxy monomers, based on diglycidyl ether of bisphenol A (DGEBA), were used. The cure agent was 4,4Ј-diaminodiphenylsulfone. PSu was miscible with DGEBA, as shown by the existence of a single glass-transition temperature within the whole composition range. The effect of PSu addition on the cure kinetics was investigated. The reaction rate of the epoxy-amine species was slightly lower in the presence of PSu. The morphology was analyzed by optical and scanning electron microscopy. A range of microstructures were obtained by control over the cure temperature, the amount of PSu incorporated, and the molecular weights of the epoxy resins. The variations in the morphology resulted from the different stages of demixing, which were arrested because of the different developments of the viscosity of the system.

“…Although numerous studies2–4 of curing kinetics of epoxy/diamines by DSC have appeared in the literature, less articles have appeared about cure processes by DMA,5, 6 and, in the last years, the high‐performance liquid chromatography (HPLC) has been applied to the study of the first steps of the polymerization reactions 7–10…”

Section: Introductionmentioning

confidence: 99%

Kinetic of epoxy resin formation by high‐performance liquid chromatography

Dopico-Garcı́a

González-Rodríguez

Redondo

et al. 2003

This article is focused on the following of the cure of an epoxy resin by high-performance liquid chromatography (HPLC) and the comparison of the data obtained with those obtained by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) techniques usually employed for characterize curing processes. A reversed-phase HPLC method with UV detection is developed to study the kinetic of the curing reaction of diglycidyl ether of bisphenol A (DGEBA) with 1,3-cyclohexanebismethylamine (1,3-BAC) at 60, 70, and 80°C, before and after gelation. The limits of quantification obtained permit the application of the proposed method until the last steps of the formation kinetic. HPLC and DSC analysis show a good correlation. The gel conversions obtained by HPLC and DMA agree well.