Experimental findings obtained by FTIR and Raman spectroscopies on montmorillonite-water mixtures at three concentration values are presented. To get some insight into the hydrogen bond network of water within the montmorillonite network, FTIR and Raman spectra have been collected as a function of time and then analyzed following two complementary approaches: An analysis of the intramolecular OH stretching mode in the spectral range of 2700–3900 cm⁻¹ in terms of two Gaussian components, and an analysis of the same OH stretching mode by wavelet cross-correlation. The FTIR and Raman investigations have been carried as a function of time for a montmorillonite-water weight composition (wt%) of 20–80%, 25–75%, and 35–65%, until the dehydrated state where the samples appear as a homogeneous rigid layer of clay. In particular, for both the FTIR and Raman spectra, the decomposition of the OH stretching band into a “closed” and an “open” contribution and the spectral wavelet analysis allow us to extract quantitative information on the time behavior of the system water content. It emerges that, the total water contribution inside the montmorillonite structure decreases as a function of time. However, the relative weight of the ordered water contribution diminishes more rapidly while the relative weight of the disordered water contribution increases, indicating that a residual water content, characterized by a highly structural disorder, rests entrapped in the montmorillonite layer structure for a longer time. From the present study, it can be inferred that the montmorillonite dehydration process promotes the layer self-assembly.

Carbon nanotubes (CNTs) thanks to their unique physical properties have been employed in several innovative applications particularly for energy storage applications. Certain technical features of carbon nanotubes, such as their remarkable specific surface, mechanical strength, as well as their electron and thermal conductivity are suitable for these applications. Furthermore, in order to produce a device, thermal treatment is needed and for this reason the trend of thermal decomposition of the tubes plays a key role in the integration process. The main purpose of this work was to characterize the thermal behavior of CNTs. In particular, we show the findings of an experimental study on CNTs performed by means of Fourier Transform InfraRed and Raman spectroscopy investigations. The collected FTIR and Raman spectra were analyzed by using two innovative procedures: spectral distance (SD) and wavelet cross correlation (XWT). From both analyses, a relaxation temperature value emerged of T = 206 °C, corresponding to a relaxation inflection point. Such a system relaxation phenomenon, occurring in the fiber CNTs, could be connected with the decay of the mechanical properties due to a decrease in the alignment and compaction of the fibers.