Thermo-oxidation of polyterpenes: influence of the physical state

The thermo-oxidation of terpene resins has been investigated with the aim o f systematically comparing their behaviours through photo-ageing. The exami nation of the chemical evolution of the poly(alpha-pinene) and poly(beta-pi nene) upon thermal-ageing shows that the observed processes are similar to those previously described for the photooxidation of these dienic polymers. But, ill contrast to photo-ageing, the thermo-oxidative kinetics of the tw o selected polypinenes are quite different. Moreover, our experimental resu lts give evidence that the kinetics of thermo-oxidative degradation drastic ally depends on the physical properties of the medium. Consequently, the di fference between the experimental temperature and the glass transition temp erature of the resin is a quite dominant factor when oxidation proceeds in the vicinity of the glass transition. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.