Spectral distance numerical approach for thermal behaviour characterization of albumen-based painting components

In this work, Attenuated Total Reflectance - Fourier Transform InfraRed (ATR - FTIR) spectroscopic technique has been employed in order to investigate the temperature behavior of albumen and of its mixture with trehalose/D_2O, the interest being associated with the wide employment of albumen in painting works both as a protective varnish and as a binder. Spectra were collected, in the 4000 cm^(-1) ÷ 400 cm^(-1) range, as a function temperature from 20°C to 80°C. The spectra profiles, in the whole spectral range and for all the temperature values, have been analysed by means of the Spectral Distance (SD) and of Cross Correlation Wavelet (XWT) approaches. In order to extract quantitative information from the comparison of the albumen and albumen/trehalose/ D2O thermal behaviours, a logistic function has been adopted. The result of this approach shows that the albumen in the presence of trehalose/D2O solution, in respect to albumen, is characterized by an increased stabilization temperature, furnished by the inflection point curve, together with a higher thermal restraint value, connected with the total SD and XWT variation with temperature.