Measurement of thermal/oxidative stability

Measurement of thermal/oxidative stability by Differential Scanning Calorimeter (DSC)

If organic compounds or especially polymers are exposed to oxygen, light and heat for longer time, an aging process takes place.

On the one hand this means a slow oxidation of some components on the other hand some molecules are not long time stable and decompose after an undefined time period.

To investigate the thermal stability of such substances, the OIT test is a common used method. OIT means “oxidation induction time”. In this test, the sample is brought to a temperature beneath the melting point in inert gas atmosphere.

Then the atmosphere is changed to oxygen or air and the calorimetric signal is measured. After a while, the oxidation will start and lead to a exothermic signal due to a tiny increase of the sample temperature. From this small slope, the point of reaction can be evaluated with the software what gives directly the OIT time. It is also possible to make a conclusion on reaction speed and decomposition rate if the resulting data is evaluated.