Quality Control of Polymers by means of DSC - Oxidative Stability

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 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 exothermic effect indicates the polymer degradation.

In the present case, 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 isothermal under N2, isothermal under air (50 ml/min) until degradation.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 N<sub>2</sub> (50 ml/min), 3 min isothermal under N<sub>2</sub>, isothermal under air (50 ml/min) until degradation.