The present work investigates the composition and the thermochemical properties of multi-component organic adhesives, aiming to gain insights into the interactions among the adhesive components, the degradation and the technologies behind their use. To achieve that, both a series of model mixtures and archaeological samples were studied. Model mixtures were prepared using raw materials (pine resins, beeswax and vegetable oil) that simulated those available in antiquity and were then subjected to degradation processes for 2 months in environmental conditions. The samples were characterised using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analysis (TGA), and Evolved Gas Analysis-Mass Spectrometry (EGA-MS). ATR-FTIR highlighted compositional differences between samples and, thanks to its rapidity, was employed for monitoring the aging process in these materials over time. Due to the large amount of data generated from ATR-FTIR, Principal Component Analysis (PCA) was subsequently applied to facilitate interpretation. Through thermo-analytical techniques, it was possible to elucidate how individual components influence the overall system under varying thermal conditions. In addition, a Design of Experiments (DoE) was employed to identify which variables most strongly affect the thermal stability of the systems.
Bertelli et al. (Mon,) studied this question.