Thermo-oxidation of polyterpenes: influence of the physical state

The thermo-oxidation of terpene resins has been investigated with the aim of systematically comparing their behaviours through photo-ageing. The examination of the chemical evolution of the poly(α-pinene) and poly(β-pinene) upon thermal-ageing shows that the observed processes are similar to those previously described for the photo-oxidation of these dienic polymers. But, in contrast to photo-ageing, the thermo-oxidative kinetics of the two selected polypinenes are quite different. Moreover, our experimental results give evidence that the kinetics of thermo-oxidative degradation drastically depends on the physical properties of the medium. Consequently, the difference between the experimental temperature and the glass transition temperature of the resin is a quite dominant factor when oxidation proceeds in the vicinity of the glass transition.