Maturation process of natural resins recorded in their thermal properties

The geothermal history of natural resins from different geographical locations was studied in terms of their age assessment and structure-properties relations. Thermal properties of resin samples were analyzed by thermogravimetry (TG) and differential scanning calorimetry (DSC), whereas infrared spectroscopy was used for analysis of the resins structure. Relative dependence between thermal parameters and degree of resin maturity was found. Glass transition process and thermal events during heating of raw materials were investigated by advanced stochastic-modulated DSC method, known as TOPEM (R), that allowed to determine the true glass transition temperature in the first heating scan. It was observed that TG method is insufficient for the resin age assessment, although it was found that there is a certain correlation between the glass transition temperature, estimated by TOPEM (R) DSC, and resin age. The natural resins proved to be reactive and sensitive material under elevated temperatures up to 200 degrees C. Subsequent processes of evaporation, relaxation and curing without significant mass loss related to degradation were observed during heating of resin samples. The aging rate in natural resins has been assessed using the intensity of 1730 cm(-1) and 1646 cm(-1) band after deconvolution of IR spectra. It may be assumed that younger resins are characterized by relatively higher reactivity (higher number of C=C bonds) and lower oxidation level.