Epoxy-amine reticulates observed by infrared spectrometry. I: Hydration process and interaction configurations of embedded H2O molecules

This article is the first one of a series devoted to the study of hydration processes in epoxy resins using infrared (FTIR) spectrometry, with a view to eventually determining the role of ambient H2O molecules in the degradat ion of these resins, particularly when they are exposed to irradiation. The starting experiment consists of recording spectra of thin films of these r esins which allows us to propose a preliminary assignment of the bands of i nterest. The second experiment consists of heating these resins. As the mai n effect of a temperature elevation is to break hydrogen bonds, the analysi s of the corresponding spectra enables us to more precisely assign bands wh ich will be of importance in the hydration process. The third experiment co nsists of hydrating these resins in a humid atmosphere. The pressure of the water vapor of this atmosphere is directly measured in the IR spectra wher e the corresponding, extremely narrow bands are easily isolated. The analys is of the spectra obtained, after subtraction of these bands due to water v apor, allows us to determine the interaction configurations of H2O molecule s which are embedded in the resins, that is, the various ways they establis h or accept hydrogen bonds to or from hydrophilic groups.