Oxidation onset temperature is a relative measure of the degree of oxidative stability of the material evaluated at a given heating rate and oxidative environment, for example, oxygen; the higher the OOT value the more stable the material. The OOT is described in Fig. 1. The OOT values can be used for comparative purposes and are not an absolute measurement, like the oxidation induction time (OIT) at a constant temperature (see Test Method E 1858). The presence or effectiveness of antioxidants may be determined by this test method.

Typical uses of this test method include the oxidative stability of edible oils and fats (oxidative rancidity), lubricants, greases, and polyolefins.

FIG. 1 DSC Oxidation Onset Temperature (OOT), Extrapolated Onset Temperature

1.1 This test method describes the determination of the oxidative properties of hydrocarbons by differential scanning calorimetry or pressure differential scanning calorimetry under linear heating rate conditions and is applicable to hydrocarbons, which oxidize exothermically in their analyzed form.

1.2 Test Method A—A differential scanning calorimeter (DSC) is used at ambient pressure, of one atmosphere of oxygen.

1.3 Test Method B—A pressure DSC (PDSC) is used at high pressure, for example, 3.5 MPa (500 psig) oxygen.

1.4 Test Method C—A differential scanning calorimeter (DSC) is used at ambient pressure of one atmosphere of air.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.