Quality Control of Polymers by means of DSC - Oxidative Stability

Oxidative-Induction Time (OIT) and Oxidative-Onset Temperature (OOT)Oxidative Induction Time (isothermal OIT) is a relative measure of the resistance of a (stabilized) material to oxidative decomposition. Oxidative-Induction Temperature (dynamic OIT) or Oxidative-Onset Temperature (OOT) is a relative measure of the resistance of a (stabilized) material to oxidative decomposition.OIT tests (Oxidative-induction time) are well-known for evaluating the oxidative resistance of polymers, in particular polyolefins.

In this example, two PP samples were heated to 200°C under a dynamic nitrogen atmosphere. The EndothermicA sample transition or a reaction is endothermic if heat is needed for the conversion.endothermic peak detected during heating illustrates the melting of the polypropylene. After 3 minutes at 200°C, the gas was switched to air. The resulting ExothermicA sample transition or a reaction is exothermic if heat is generated.exothermic effect indicates the polymer degradation.

In the present case, OxidationOxidation can describe different processes in the context of thermal analysis.oxidation occurs earlier for sample A than for sample B (OIT 6.6 min vs. 11.6 min).

OIT test on PP. Sample masses: 9.48 mg (sample A) and 9.55 mg (sample B); heating to 200°C at 20 K/min under N2 (50 ml/min), 3 min IsothermalTests at controlled and constant temperature are called isothermal.isothermal under N2, isothermal under air (50 ml/min) until degradation.