Effect of heat treatment at mild temperatures on the composition and physico-chemical properties of Scots pine resin

Abstract

Abstract A major function of resin in trees is to provide defense against external attacks by releasing the resin flow on the attacked or damaged area. Nonetheless, the leakage of the resin on the surface can have a negative aesthetic and economic impact on wood material. The aim of this study was to investigate how heat treatment affects the chemo-physical properties of the resin of Pinus sylvestris L. in order to hinder the exudation on wood surface during service. To reduce the fluidity of the resin, it is necessary to remove the volatile fraction of resin, and several studies have been carried out in this direction, providing useful information about this process. The results from thermal analyses (DSC, TGA) confirmed that heat treatment at mild temperatures, 80 °C, 90 °C and 100 °C, respectively, had a positive effect on increasing the glass transition temperature Tg and showed a good correlation between the Tg and the residual volatile content. FTIR spectroscopy, before and after heat treatment, did not show major changes in chemical structures, whilst UHPLC-DAD-MS analysis revealed significant differences for the ratios of compounds, which are the result of possible chemical reactions, such as dehydrogenation, oxidation and isomerization.