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

Abstract

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.

Effect of amine‐terminated butadiene‐acrylonitrile/clay combinations on the structure and properties of epoxy nanocomposites

“…This increase undoubtedly corresponds to phase separation via nucleation and growth mechanism expected for the low concentrations of the second phase polymer28–30 that we used. A similar increase in the particle size with increasing temperature has been reported for analogous epoxy systems by others 28, 31, 32. The increase of particle size with increasing temperature indicates that the lower viscosity at the CP31 at elevated temperature is the primary contributor to particle growth.…”

The synthesis and curing kinetics study of a new fluorinated polyurethane with fluorinated side chains attached to soft blocks

“…The ratio between the absorbances at 2270 cm À1 and the reference (constant) band at 1530 cm À1 was considered in order to evaluate the conversion of NCO content at t s . Under the kinetically controlled conditions, the reaction rate can be expressed by an Arrhenius rate expression as follows: [48][49][50][51]…”

Accurate Evaluation of Dynamics and Specific Interactions in PLA/TiO2 Nanocomposites

“…However, there are only a few research works which, based on NIR spectroscopy, have offer valuable information about structure and conformational changes of many molecules [9][10][11][12]. Besides, the use of FTIR spectroscopy in the near range with the aid of fluorescence spectroscopy has also allowed studying different processes such as chemical reactions [13,14], phase separation [15] or water absorption processes [16].…”