Estimation of activation energies for thermo-oxidative degradations of LDPE and NBR from non-isothermal and isothermal DTA data

Results obtained on the thermooxidative degradations of LDPE (low-density polyethylene) and NBR (nitrile-butadiene: rubber) are presented. The activation energies for the thermooxidations leading to solid products were estimated. For LDPE. the activation energies obtained from non-isothermal data are in satisfactory agreement with those obtained from isothermal data. For NBR, the isothermal activation energy is approximate to 16% higher than the non-isothermal one. This difference is due to the morphological changes undergone by NBR during its heating at the rather high temperatures at which isothermal measurements were performed.