ASTM E1858-23

Standard Test Methods for Determining Oxidation Induction Time of Hydrocarbons by Differential Scanning Calorimetry

SIGNIFICANCE AND USE
5.1 Oxidative induction time is a relative measure of the degree of oxidative stability of the material evaluated at the isothermal temperature of the test. The presence, quantity or effectiveness of antioxidants may be determined by this method. The OIT values thus obtained may be compared from one hydrocarbon to another or to a reference material to obtain relative oxidative stability information.  
5.2 Typical uses include the oxidative stability of edible oils and fats (oxidative rancidity), lubricants, greases, and polyolefins.
SCOPE
1.1 These test methods describe the determination of the oxidative properties of hydrocarbons by differential scanning calorimetry or pressure differential scanning calorimetry and is applicable to hydrocarbons that oxidize exothermically in their analyzed form.  
1.2 Test Method A—A differential scanning calorimeter (DSC) is used at ambient pressure, for example, about 100 kPa 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 Units—The values stated in SI units are to be regarded as standard. Imperial units are provided for user convenience and are not the standard.  
1.5 These test methods are related to ISO 11357–6 but is different in technical content. These test methods are related to CEC L-85–T but includes additional experimental conditions.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  Specific precautionary statements are given in 7.4 and 12.10.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Mar-2023
• ICS: 71.080.01 - Organic chemicals in general
• Technical Committee: E37 - Thermal Measurements
• Drafting Committee: E37.01 - Calorimetry and Mass Loss

Relations

• Refers: ASTM E473-23b - Standard Terminology Relating to Thermal Analysis and Rheology
• Effective Date: 01-Oct-2023
• Refers: ASTM D5482-20 - Standard Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method—Atmospheric)
• Effective Date: 01-May-2020
• Refers: ASTM D6186-19 - Standard Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)
• Effective Date: 01-Jul-2019
• Refers: ASTM E3142-18 - Standard Test Method for Thermal Lag of Thermal Analysis Apparatus
• Effective Date: 15-Jan-2018
• Refers: ASTM D5885/D5885M-15 - Standard Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure Differential Scanning Calorimetry
• Effective Date: 01-May-2015
• Refers: ASTM E473-14 - Standard Terminology Relating to Thermal Analysis and Rheology
• Effective Date: 15-Aug-2014
• Refers: ASTM D6186-08(2013) - Standard Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)
• Effective Date: 01-Dec-2013
• Refers: ASTM E1860-13 - Standard Test Method for Elapsed Time Calibration of Thermal Analyzers
• Effective Date: 15-Sep-2013
• Refers: ASTM D5482-07(2013) - Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method—Atmospheric)
• Effective Date: 01-Jun-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM D3350-12 - Standard Specification for Polyethylene Plastics Pipe and Fittings Materials
• Effective Date: 01-Apr-2012
• Refers: ASTM D3350-12e1 - Standard Specification for Polyethylene Plastics Pipe and Fittings Materials
• Effective Date: 01-Apr-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E473-11a - Standard Terminology Relating to Thermal Analysis and Rheology
• Effective Date: 15-Jun-2011
• Refers: ASTM E473-11 - Standard Terminology Relating to Thermal Analysis and Rheology
• Effective Date: 01-Apr-2011

Overview

ASTM E1858-23: Standard Test Methods for Determining Oxidation Induction Time (OIT) of Hydrocarbons by Differential Scanning Calorimetry is an internationally recognized standard developed by ASTM. This standard outlines precise methods for measuring the oxidative stability of hydrocarbons using differential scanning calorimetry (DSC) or pressure DSC (PDSC). It assesses how resistant a material is to oxidation under specific test conditions, providing vital data on the effectiveness of antioxidants and the comparative stability of hydrocarbons, such as edible oils, lubricants, greases, and polyolefins.

The methods detailed in ASTM E1858-23 are important for quality control, product development, and regulatory compliance within the chemical, petrochemical, food, and polymer industries.

Key Topics

• Oxidation Induction Time (OIT):
  OIT represents the time interval necessary to initiate oxidation in a hydrocarbon sample under controlled, isothermal conditions. It is a crucial quantitative indicator for oxidative stability.

• Test Methods:

  • Method A: Utilizes a standard DSC at ambient oxygen pressure (e.g., around 100 kPa).
  • Method B: Employs a pressure DSC (PDSC) at higher oxygen pressures (e.g., about 3.5 MPa). Both methods involve precise control of temperature and oxygen flow, with specific calibration protocols to ensure reliable results.

• Comparative Measurement:
  OIT values allow users to compare oxidative stability across different hydrocarbon samples or against reference materials, offering insight into the effectiveness and quantity of antioxidants.

• Calibration & Equipment:
  Routine calibration and maintenance of DSC and PDSC equipment are required to achieve accurate and repeatable OIT measurements. Proper specimen handling and pan cleaning procedures are also outlined.

Applications

• Edible Oils and Fats:
  Measurement of oxidative rancidity, enabling manufacturers and quality assurance teams to ensure shelf life and product safety.

• Lubricants and Greases:
  Determining the oxidative stability to gauge performance in high-temperature and oxidative environments, vital for automotive, industrial, and machinery applications.

• Polyolefins and Geosynthetics:
  Assessing stability and antioxidant content in polymers such as polyethylene, which is important for packaging, piping, and geotextile industries.

• Quality and Regulatory Assurance:
  Results obtained by ASTM E1858-23 are essential for product development, batch consistency, and compliance with industry regulations.

Related Standards

For broader context and complementary information, ASTM E1858-23 references and aligns with the following standards:

• ASTM D3895: Test Method for Oxidative-Induction Time of Polyolefins by DSC
• ASTM D3350: Specification for Polyethylene Plastics Pipe and Fittings Materials
• ASTM D4565: Test Methods for Performance of Insulations and Jackets for Telecommunication Wire and Cable
• ASTM D6186: Oxidation Induction Time of Lubricating Oils by PDSC
• ASTM D5885: Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure DSC
• ISO 11357-6: Plastics - DSC - Part 6: Determination of OIT and Oxidation Induction Temperature
• CEC L-85-T: Hot Surface Oxidation of Lubricants Measured by PDSC

These related standards further reinforce industry best practices for oxidative stability testing, thermal analysis, and calorimetry of hydrocarbons.

---

Keywords: oxidation induction time (OIT), oxidative stability, differential scanning calorimetry (DSC), pressure DSC (PDSC), hydrocarbons, antioxidant analysis, ASTM E1858-23, polymer stability, lubricant testing, edible oil analysis, thermal analysis standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1858 − 23
Standard Test Methods for
Determining Oxidation Induction Time of Hydrocarbons by
Differential Scanning Calorimetry
This standard is issued under the fixed designation E1858; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 These test methods describe the determination of the 2.1 ASTM Standards:
oxidative properties of hydrocarbons by differential scanning D3350 Specification for Polyethylene Plastics Pipe and Fit-
calorimetry or pressure differential scanning calorimetry and is tings Materials
applicable to hydrocarbons that oxidize exothermically in their D3895 Test Method for Oxidative-Induction Time of Poly-
analyzed form. olefins by Differential Scanning Calorimetry
D4565 Test Methods for Physical and Environmental Per-
1.2 Test Method A—A differential scanning calorimeter
formance Properties of Insulations and Jackets for Tele-
(DSC) is used at ambient pressure, for example, about 100 kPa
communications Wire and Cable
of oxygen.
D5482 Test Method for Vapor Pressure of Petroleum Prod-
1.3 Test Method B—A pressure DSC (PDSC) is used at high
ucts and Liquid Fuels (Mini Method—Atmospheric)
pressure, for example, 3.5 MPa (500 psig) oxygen.
D5885/D5885M Test Method for Oxidative Induction Time
1.4 Units—The values stated in SI units are to be regarded of Polyolefin Geosynthetics by High-Pressure Differential
Scanning Calorimetry
as standard. Imperial units are provided for user convenience
and are not the standard. D6186 Test Method for Oxidation Induction Time of Lubri-
cating Oils by Pressure Differential Scanning Calorimetry
1.5 These test methods are related to ISO 11357–6 but is
(PDSC)
different in technical content. These test methods are related to
E473 Terminology Relating to Thermal Analysis and Rhe-
CEC L-85–T but includes additional experimental conditions.
ology
1.6 This standard does not purport to address all of the
E691 Practice for Conducting an Interlaboratory Study to
safety concerns, if any, associated with its use. It is the
Determine the Precision of a Test Method
responsibility of the user of this standard to establish appro-
E967 Test Method for Temperature Calibration of Differen-
priate safety, health, and environmental practices and deter-
tial Scanning Calorimeters and Differential Thermal Ana-
mine the applicability of regulatory limitations prior to use.
lyzers
Specific precautionary statements are given in 7.4 and 12.10.
E1860 Test Method for Elapsed Time Calibration of Ther-
1.7 This international standard was developed in accor-
mal Analyzers
dance with internationally recognized principles on standard-
E3142 Test Method for Thermal Lag of Thermal Analysis
ization established in the Decision on Principles for the
Apparatus
Development of International Standards, Guides and Recom-
2.2 Other Standards:
mendations issued by the World Trade Organization Technical
ISO 11357–6 Plastice-Differential Scanning Calorimetry
Barriers to Trade (TBT) Committee.
(DSC) — Part 6: Determination of Oxidation Induction
These test methods are under the direct jurisdiction of Committee E37 on
Thermal Measurements and is the direct responsibility of Subcommittee E37.01 on
Calorimetry and Mass Loss. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2023. Published April 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ε1
approved in 1997. Last previous edition approved in 2015 as E1858 – 08 (2015) . Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/E1858-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1858 − 23
Time (Isothermal OIT) and Oxidation Induction Tempera- method. The OIT values thus obtained may be compared from
ture (Dynamic OIT) one hydrocarbon to another or to a reference material to obtain
CEC L-85–T-99 Oxidative Stability of Lubricants Measured relative oxidative stability information.
by PDSC
5.2 Typical uses include the oxidative stability of edible oils
and fats (oxidative rancidity), lubricants, greases, and polyole-
3. Terminology
fins.
3.1 Definitions:
3.1.1 Specific technical terms used in these test methods are
6. Interferences
given in Terminology E473, including differential scanning
6.1 This test method involves the continuous monitoring of
calorimetry, extrapolated onset value, and exotherm.
the specimen temperature within the test chamber’s enclosed
3.2 Oxidation Induction Time (OIT), n—the time interval
environment of a flowing, static, or self-generated gaseous
required to isothermally initiate oxidation.
atmosphere during execution of the stipulated procedure. In
3.2.1 Discussion—The oxidation induction time is consid-
DSC apparatus, the temperature sensor utilized to measure the
ered a quantitative measure of oxidative stability and often as
specimen temperature is not in direct contact with the speci-
a relative indicator of anti-oxidant content.
men. The measured temperature is that of the temperature
sensor itself. To obtain the correct specimen temperature, the
4. Summary of Test Method
DSC apparatus must be temperature calibrated at equivalent
4.1 In thermal analysis, a physical property of a material is
experimental conditions so that the recorded temperature
measured either as a function of time at a specified constant
correctly indicates the specimen temperature (see Test Methods
temperature, or more frequently, as a function of temperature
E967 and E3142).
under conditions of a fixed rate of temperature change. The
measured property is the dependent variable and the measured 6.2 Temperature sensors are subject to degraded perfor-
temperature and time are the independent variables. mance with age and exposure to the DSC test chamber
atmosphere. It is therefore imperative that the apparatus is
4.2 The test specimen in an aluminum pan and the reference
temperature calibrated regularly. Committee E37 recommends
aluminum pan are heated to a specified constant test tempera-
at a minimum annual calibration of all signals or more
ture in an oxygen environment. Heat flow out of the specimen
frequently.
is monitored at an isothermal temperature until the oxidative
reaction is manifested by heat evolution on the thermal curve.
7. Apparatus
The oxidative induction time (OIT), a relative measure of
oxidative stability at the test temperature, is determined from
7.1 Differential Scanning Calorimeter (DSC) or Pressure
data recorded during the isothermal test. The OIT measurement
Differential Scanning Calorimeter (PDSC)—Multiple genera-
is initiated upon reaching the isothermal test temperature.
tions of differential scanning calorimeters from numerous
commercial suppliers, as well as in-house custom apparatus,
4.3 For some particularly stable materials, the OIT may be
utilizing a variety of temperature and heat flow sensors in
quite long (>120 min) at the specified elevated temperatures of
various configurations may be available to the user. While all
the experiment. Under these circumstances, the OIT may be
such apparatus capabilities may not be equivalent, for purposes
reduced by increasing the isothermal temperature or increasing
of this test method, any DSC instrumentation that meets the
the pressure of oxygen purge gas, or both. Conversely, reac-
following criteria should be able to generate acceptable results
tions that proceed too rapidly, with a short OIT, may be
7.1.1 DSC Test Chamber, composed of:
extended by decreasing the test temperature or reducing the
partial pressure of oxygen, or both. By admixing oxygen gas 7.1.1.1 A Furnace(s), to provide uniform controlled heating
with a suitable diluent, for example, nitrogen, the OIT will be
of a specimen and reference to a constant temperature or at a
increased (see Test Methods D3895, D4565, D5482, D6186, constant rate within the applicable temperature range of these
and D5885/D5885M, and Specification D3350). test methods.
7.1.1.2 A Temperature Sensor, to provide an indication of
NOTE 1—For some systems, the use of copper pans to catalyze
the specimen/furnace temperature to 60.4 °C.
oxidation will reduce the oxidation induction time for a particular
temperature. The results, however, will not correlate with non-catalyzed
7.1.1.3 Differential Sensors, to detect a heat flow difference
tests.
between specimen and reference with a sensitivity of 5 μW.
7.1.1.4 A means of sustaining a Test Chamber Environment
5. Significance and Use
of a purge gas of 50 mL/min within 5 %.
5.1 Oxidative induction time is a relative measure of the
7.1.2 Temperature Controller, capable of executing a spe-
degree of oxidative stability of the material evaluated at the
cific temperature program by operating the furnace(s) between
isothermal temperature of the test. The presence, quantity or
selected temperature limits at a rate of temperature change of
effectiveness of antioxidants may be determined by this
40 °C ⁄min constant to 1 % and an isothermal temperature
constant to 60.4 °C
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
NOTE 2—In certain cases when the sample under study is of high
4th Floor, New York, NY 10036, http://www.ansi.org.
Available from the Coordinating European Council website, http:// volatility (for example, low molecular weight hydrocarbons), either the
www.cectests.org. use of pressures in excess of one atmosphere or lower temperatures may
E1858 − 23
be required. The operator is cautioned to verify (with apparatus manufac-
8. Materials
turer) the maximum oxygen pressure at which the apparatus may be safely
8.1 Oxygen, extra dry, purity of not less than 99.50 % by
operated.
volume. (Warning—Oxidizer. Gas under pressure.)
7.1.3 A Data Collection Device, to provide a means of
8.2 Indium, of not less than 99.9 % by mass.
acquiring, storing, and displaying measured or calculated
signals, or both. The minimum output signals required for DSC
8.3 Tin, of not less than 99.9 % by mass.
are heat flow, temperature and time.
9. Precautions
NOTE 3—The capability to record the first derivative of the heat flow
curve will be helpful in cases where the baseline is not constant. 9.1 Warning—Oxygen is a strong oxidizer and vigorously
accelerates combustion. Keep surfaces clean.
7.2 Containers (pans, crucibles, etc.), that are inert to the
specimen and reference materials and that are of a suitable 9.2 Warning—Oxygen is a strong oxidizer and may react
with aluminum pans.
structural shape and integrity to contain the specimen and
reference materials.
9.3 If the specimen is heated to decomposition, toxic or
corrosive products may be released.
7.3 For use in Test Method B.
7.3.1 Pressure System, consisting of:
9.4 For certain types of PDSC, it is recommended that the
7.3.1.1 A Pressure Vessel, or similar means of sealing the flow be set up with a “reverse flow” implementation to ensure
test chamber at any applied oxygen pressure within the
there is no contact of decomposed hydrocarbons with incoming
pressure limits of these test methods. oxygen within the instrument. See instrument designer’s rec-
7.3.1.2 A source of pressurized oxygen or air capable of ommendation on “reverse flow.”
sustaining a regulated gas pressure in the test chamber of up to
10. Sampling
3.2 MPa.
7.3.1.3 A Pressure Transducer, or similar device to measure
10.1 If the sample is a liquid or powder, mix thoroughly
the pressure inside the test chamber to 60.2 MPa, including
prior to sampling.
any temperature dependence of the transducer.
10.2 In the absence of information, samples are to be
analyzed as received. If some heat or mechanical treatment is
NOTE 4—The link between the test chamber and the pressure transducer
should allow for fast pressure equilibrium to ensure accurate recording of applied to the sample prior to analysis, this treatment should be
the pressure above the specimen during testing.
in nitrogen and noted in the report. If some heat treatment is
used prior to oxidative testing, then record any mass loss as a
7.3.1.4 A Pressure Regulator, or similar device to adjust the
result of the treatment.
applied pressure in the test chamber to 60.2 MPa of the
desired value.
11. Calibration
7.3.1.5 A Ballast, or similar means to maintain the applied
pressure in the test chamber constant to 60.2 MPa. 11.1 Calibrate the temperature output of the instrument
using Test Method E967 except that a heating rate of 1 °C ⁄min
7.3.1.6 Valves, to control the gas in the test chamber or to
shall be used to approach the isothermal conditions of this test.
isolate components of the pressure system.
Accomplish temperature calibration at ambient pressure with a
7.4 Flow Meter, capable of reading 50 mL/min or another
calibrant(s) that bracket(s) the temperature range to be used for
selected flow rate, accurate to within 6 5 %. Ensure the
subsequent testing, for example, indium and tin. Perform
flowmeter is calibrated for oxygen. Contact a supplier of flow
calibration under ambient pressure conditions.
meters for specific details on calibration, see Note 8, following
NOTE 6—This assumes known temperature calibration with dependenc
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: E1858 − 08 (Reapproved 2015) E1858 − 23
Standard Test Methods for
Determining Oxidation Induction Time of Hydrocarbons by
Differential Scanning Calorimetry
This standard is issued under the fixed designation E1858; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Warning notes were editorially updated throughout in May 2015.
1. Scope
1.1 These test methods describe the determination of the oxidative properties of hydrocarbons by differential scanning calorimetry
or pressure differential scanning calorimetry and is applicable to hydrocarbons that oxidize exothermically in their analyzed form.
1.2 Test Method A—A differential scanning calorimeter (DSC)(DSC) is used at ambient pressure, for example, about 100 kPa of
oxygen.
1.3 Test Method B—A pressure DSC (PDSC)(PDSC) is used at high pressure, for example, 3.5 MPa (500 psig) oxygen.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this Imperial
units are provided for user convenience and are not the standard.
1.5 These test methods are related to ISO 11357–6 but is different in technical content. These test methods are related to CEC
L-85–T but includes additional experimental conditions.
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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.47.4 and 11.1012.10.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D3350 Specification for Polyethylene Plastics Pipe and Fittings Materials
D3895 Test Method for Oxidative-Induction Time of Polyolefins by Differential Scanning Calorimetry
D4565 Test Methods for Physical and Environmental Performance Properties of Insulations and Jackets for Telecommunications
Wire and Cable
These test methods are under the direct jurisdiction of Committee E37 on Thermal Measurements and is the direct responsibility of Subcommittee E37.01 on Calorimetry
and Mass Loss.
Current edition approved May 1, 2015March 15, 2023. Published May 2015April 2023. Originally approved in 1997. Last previous edition approved in 20082015 as
ε1
E1858 – 08.E1858 – 08 (2015) . DOI: 10.1520/E1858-08R15E01.10.1520/E1858-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1858 − 23
D5482 Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method—Atmospheric)
D5885D5885/D5885M Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure Differential
Scanning Calorimetry
D6186 Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)
E473 Terminology Relating to Thermal Analysis and Rheology
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E967 Test Method for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers
E1860 Test Method for Elapsed Time Calibration of Thermal Analyzers
E3142 Test Method for Thermal Lag of Thermal Analysis Apparatus
2.2 Other Standards:
ISO 11357–6 Plastice-Differential Scanning Calorimetry (DSC) — Part 6: Determination of Oxidation Induction Time
(Isothermal OIT) and Oxidation Induction Temperature (Dynamic OIT)
CEC L-85–TL-85–T-99 Hot Surface OxidationOxidative Stability of Lubricants Measured by PDSC
3. Terminology
3.1 Definitions:
3.1.1 Specific technical terms used in these test methods are given in Terminology E473., including differential scanning
calorimetry, extrapolated onset value, and exotherm.
3.2 Oxidation Induction Time (OIT), n—the time interval required to isothermally initiate oxidation.
3.2.1 Discussion—
The oxidation induction time is considered a quantitative measure of oxidative stability and often as a relative indicator of
anti-oxidant content.
4. Summary of Test Method
4.1 In thermal analysis, a physical property of a material is measured either as a function of time at a specified constant
temperature, or more frequently, as a function of temperature under conditions of a fixed rate of temperature change. The measured
property is the dependent variable and the measured temperature and time are the independent variables.
4.2 The test specimen in an aluminum pan and the reference aluminum pan are heated to a specified constant test temperature in
an oxygen environment. Heat flow out of the specimen is monitored at an isothermal temperature until the oxidative reaction is
manifested by heat evolution on the thermal curve. The oxidative induction time (OIT), a relative measure of oxidative stability
at the test temperature, is determined from data recorded during the isothermal test. The OIT measurement is initiated upon
reaching the isothermal test temperature.
4.3 For some particularly stable materials, the OIT may be quite long (>120 min) at the specified elevated temperatures of the
experiment. Under these circumstances, the OIT may be reduced by increasing the isothermal temperature or increasing the
pressure of oxygen purge gas, or both. Conversely, reactions that proceed too rapidly, with a short OIT, may be extended by
decreasing the test temperature or reducing the partial pressure of oxygen, or both. By admixing oxygen gas with a suitable diluent,
for example, nitrogen, the OIT will be increased (see Test Methods D3895, D4565, D5482, D6186, and D5885/D5885M, and
Specification D3350).
NOTE 1—For some systems, the use of copper pans to catalyze oxidation will reduce the oxidation induction time for a particular temperature. The results,
however, will not correlate with non-catalyzed tests.
5. Significance and Use
5.1 Oxidative induction time is a relative measure of the degree of oxidative stability of the material evaluated at the isothermal
temperature of the test. The presence, quantity or effectiveness of antioxidants may be determined by this method. The OIT values
thus obtained may be compared from one hydrocarbon to another or to a reference material to obtain relative oxidative stability
information.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http://www.sae.org.the Coordinating European Council website,
http://www.cectests.org.
E1858 − 23
5.2 Typical uses include the oxidative stability of edible oils and fats (oxidative rancidity), lubricants, greases, and polyolefins.
6. Interferences
6.1 This test method involves the continuous monitoring of the specimen temperature within the test chamber’s enclosed
environment of a flowing, static, or self-generated gaseous atmosphere during execution of the stipulated procedure. In DSC
apparatus, the temperature sensor utilized to measure the specimen temperature is not in direct contact with the specimen. The
measured temperature is that of the temperature sensor itself. To obtain the correct specimen temperature, the DSC apparatus must
be temperature calibrated at equivalent experimental conditions so that the recorded temperature correctly indicates the specimen
temperature (see Test Methods E967 and E3142).
6.2 Temperature sensors are subject to degraded performance with age and exposure to the DSC test chamber atmosphere. It is
therefore imperative that the apparatus is temperature calibrated regularly. Committee E37 recommends at a minimum annual
calibration of all signals or more frequently.
7. Apparatus
7.1 Differential Scanning Calorimeter (DSC) or Pressure Differential Scanning Calorimeter, Calorimeter (PDSC)—the essential
instrumentation required to provide the minimum differential scanning calorimetric capability for these test methods include:Mul-
tiple generations of differential scanning calorimeters from numerous commercial suppliers, as well as in-house custom apparatus,
utilizing a variety of temperature and heat flow sensors in various configurations may be available to the user. While all such
apparatus capabilities may not be equivalent, for purposes of this test method, any DSC instrumentation that meets the following
criteria should be able to generate acceptable results
7.1.1 DSC Test Chamber, composed of:
7.1.1.1 A Furnace(s), to provide uniform controlled heating of a specimen and reference to a constant temperature or at a constant
rate within the applicable temperature range of these test methods.
7.1.1.2 A Temperature Sensor, to provide an indication of the specimen/furnace temperature to 60.4°C.60.4 °C.
7.1.1.3 Differential Sensors, to detect a heat flow difference between specimen and reference with a sensitivity of 5 μW.
7.1.1.4 A means of sustaining a Test Chamber Environment of a purge gas of 50 mL/min within 5 %.
7.1.2 Temperature Controller, capable of executing a specific temperature program by operating the furnace(s) between selected
temperature limits at a rate of temperature change of 40°C/min40 °C ⁄min constant to 1 % and an isothermal temperature constant
to 60.4°C60.4 °C
NOTE 2—In certain cases when the sample under study is of high volatility (for example, low molecular weight hydrocarbons), either the use of pressures
in excess of one atmosphere or lower temperatures may be required. The operator is cautioned to verify (with apparatus manufacturer) the maximum
oxygen pressure at which the apparatus may be safely operated.
7.1.3 A Data Collection Device, to provide a means of acquiring, storing, and displaying measured or calculated signals, or both.
The minimum output signals required for DSC are heat flow, temperature and time.
NOTE 3—The capability to record the first derivative of the heat flow curve will be helpful in cases where the baseline is not constant.
7.2 Containers (pans, crucibles, etc.), that are inert to the specimen and reference materials and that are of a suitable structural
shape and integrity to contain the specimen and reference materials.
7.3 For use in Test Method B.
7.3.1 Pressure System, consisting of:
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7.3.1.1 A Pressure Vessel, or similar means of sealing the test chamber at any applied oxygen pressure within the pressure limits
of these test methods.
7.3.1.2 A source of pressurized oxygen or air capable of sustaining a regulated gas pressure in the test chamber of up to 3.2 MPa.
7.3.1.3 A Pressure Transducer, or similar device to measure the pressure inside the test chamber to 60.2 MPa, including any
temperature dependence of the transducer.
NOTE 4—The link between the test chamber and the pressure transducer should allow for fast pressure equilibrium to ensure accurate recording of the
pressure above the specimen during testing.
7.3.1.4 A Pressure Regulator, or similar device to adjust the applied pressure in the test chamber to 60.2 MPa of the desired value.
7.3.1.5 A Ballast, or similar means to maintain the applied pressure in the test chamber constant to 60.2 MPa.
7.3.1.6 Valves, to control the gas in the test chamber or to isolate components of the pressure system.
7.4 Flow meter,Meter, capable of reading 50 mL/min or another selected flow rate, accurate to within 6 5 %. Ensure the flowmeter
is calibrated for oxygen. Contact a supplier of flow meters for specific details on calibration, see Note 68, following Section
11.412.4. (Warning—Use metal or fluoropolymer tubing with oxygen rather than the commonly used rubber or polyvinyl chloride
plastic tubing. There have been hazardous situations with prolonged use of certain polymer tubing in oxygen service.)
NOTE 5—Gas delivery tubing should be kept as short as possible to minimize “dead” volume.
7.5 Analytical Balance with a capacity of at least 100 mg and capable of weighing to the nearest 0.01 mg or less than 1 % of the
specimen mass.
7.6 Specimen Containers, and sample holders are the aluminum sample pans and should be inert to the sample and the oxidizing
gas. The pans shall be clean, dry, and flat. A typical cylindrical pan has the following dimensions: height, 1.51.5 mm to 2.5 mm
and outer diameter, 5.05.0 mm to 6.0 mm.
7.6.1 New sample pans shall be cleaned by the procedure found in Annex A1.
8. Materials
8.1 Oxygen, extra dry, purity of not less than 99.50 % by volume. (Warning—Oxidizer. Gas under pressure.)
8.2 Indium, of not less than 99.9 % by mass.
8.3 Tin, of not less than 99.9 % by mass.
9. Precautions
9.1 Warning—Oxygen is a strong oxidizer and vigorously accelerates combustion. Keep surfaces clean.
9.2 Warning—Oxygen is a strong oxidizer and may react with aluminum pans.
9.3 If the specimen is heated to decomposition, toxic or corrosive products may be released.
9.4 For certain types of PDSC, it is recommended that the flow be set up with a “reverse flow” implementation to ensure there
is no contact of decomposed hydrocarbons with incoming oxygen within the instrument. See instrument designer’s recommen-
dation on “reverse flow.”
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10. Sampling
10.1 If the sample is a liquid or powder, mix thoroughly prior to sampling.
10.2 In the absence of information, samples are
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