ASTM E1858-08(2015)e1

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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 health practices and determine the applicability of regulatory limitations prior to use.  Specific precautionary statements are given in 6.4 and 11.10.

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 71.080.01 - Organic chemicals in general
• Technical Committee: E37 - Thermal Measurements
• Drafting Committee: E37.01 - Calorimetry and Mass Loss

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: E1858 − 08 (Reapproved 2015)
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 olefins by Differential Scanning Calorimetry
D4565 Test Methods for Physical and Environmental Per-
1.1 These test methods describe the determination of the
formance Properties of Insulations and Jackets for Tele-
oxidative properties of hydrocarbons by differential scanning
communications Wire and Cable
calorimetry or pressure differential scanning calorimetry and is
D5482 Test Method for Vapor Pressure of Petroleum Prod-
applicable to hydrocarbons that oxidize exothermically in their
ucts (Mini Method—Atmospheric)
analyzed form.
D5885 Test Method for Oxidative Induction Time of Poly-
1.2 Test Method A—A differential scanning calorimeter
olefin Geosynthetics by High-Pressure Differential Scan-
(DSC) is used at ambient pressure, for example, about 100 kPa
ning Calorimetry
of oxygen.
D6186 Test Method for Oxidation Induction Time of Lubri-
cating Oils by Pressure Differential Scanning Calorimetry
1.3 Test Method B—A pressure DSC (PDSC) is used at high
pressure, for example, 3.5 MPa (500 psig) oxygen. (PDSC)
E473 Terminology Relating to Thermal Analysis and Rhe-
1.4 The values stated in SI units are to be regarded as
ology
standard. No other units of measurement are included in this
E691 Practice for Conducting an Interlaboratory Study to
standard.
Determine the Precision of a Test Method
1.5 These test methods are related to ISO 11357–6 but is
E967 Test Method for Temperature Calibration of Differen-
different in technical content. These test methods are related to
tial Scanning Calorimeters and Differential Thermal Ana-
CEC L-85–T but includes additional experimental conditions.
lyzers
1.6 This standard does not purport to address all of the E1860 Test Method for Elapsed Time Calibration of Ther-
safety concerns, if any, associated with its use. It is the mal Analyzers
responsibility of the user of this standard to establish appro-
2.2 Other Standards:
priate safety and health practices and determine the applica-
ISO 11357–6 Plastice-Differential Scanning Calorimetry
bility of regulatory limitations prior to use. Specific precau-
(DSC) — Part 6: Oxidation Induction Time
tionary statements are given in 6.4 and 11.10.
CEC L-85–T Hot Surface Oxidation
2. Referenced Documents 3. Terminology
3.1 Definitions:
2.1 ASTM Standards:
D3350 Specification for Polyethylene Plastics Pipe and Fit- 3.1.1 Specific technical terms used in these test methods are
given in Terminology E473.
tings Materials
D3895 Test Method for Oxidative-Induction Time of Poly-
4. Summary of Test Method
4.1 The test specimen in an aluminum pan and the reference
These test methods are under the direct jurisdiction of Committee E37 on
aluminum pan are heated to a specified constant test tempera-
Thermal Measurements and is the direct responsibility of Subcommittee E37.01 on
ture in an oxygen environment. Heat flow out of the specimen
Calorimetry and Mass Loss.
is monitored at an isothermal temperature until the oxidative
Current edition approved May 1, 2015. Published May 2015. Originally
approved in 1997. Last previous edition approved in 2008 as E1858 – 08. DOI:
10.1520/E1858-08R15E01.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM 4th Floor, New York, NY 10036, http://www.ansi.org.
Standards volume information, refer to the standard’s Document Summary page on Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,
the ASTM website. PA 15096-0001, http://www.sae.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E1858 − 08 (2015)
turer) the maximum oxygen pressure at which the apparatus may be safely
reaction is manifested by heat evolution on the thermal curve.
operated.
The oxidative induction time (OIT), a relative measure of
oxidative stability at the test temperature, is determined from
6.1.3 A Data Collection Device, to provide a means of
data recorded during the isothermal test. The OIT measurement
acquiring, storing, and displaying measured or calculated
is initiated upon reaching the isothermal test temperature.
signals, or both. The minimum output signals required for DSC
are heat flow, temperature and time.
4.2 For some particularly stable materials, the OIT may be
quite long (>120 min) at the specified elevated temperatures of
NOTE 3—The capability to record the first derivative of the heat flow
the experiment. Under these circumstances, the OIT may be
curve will be helpful in cases where the baseline is not constant.
reduced by increasing the isothermal temperature or increasing
6.2 Containers (pans, crucibles, etc.), that are inert to the
the pressure of oxygen purge gas, or both. Conversely, reac-
specimen and reference materials and that are of a suitable
tions that proceed too rapidly, with a short OIT, may be
structural shape and integrity to contain the specimen and
extended by decreasing the test temperature or reducing the
reference materials.
partial pressure of oxygen, or both. By admixing oxygen gas
with a suitable diluent, for example, nitrogen, the OIT will be
6.3 For use in Test Method B.
increased (see Test Methods D3895, D4565, D5482, D6186,
6.3.1 Pressure System, consisting of:
and Specification D3350).
6.3.1.1 A Pressure Vessel, or similar means of sealing the
test chamber at any applied oxygen pressure within the
NOTE 1—For some systems, the use of copper pans to catalyze
oxidation will reduce the oxidation induction time for a particular
pressure limits of these test methods.
temperature. The results, however, will not correlate with non-catalyzed
6.3.1.2 A source of pressurized oxygen or air capable of
tests.
sustaining a regulated gas pressure in the test chamber of up to
3.2 MPa.
5. Significance and Use
6.3.1.3 A Pressure Transducer, or similar device to measure
5.1 Oxidative induction time is a relative measure of the
the pressure inside the test chamber to 60.2 MPa, including
degree of oxidative stability of the material evaluated at the
any temperature dependence of the transducer.
isothermal temperature of the test. The presence, quantity or
effectiveness of antioxidants may be determined by this
NOTE 4—The link between the test chamber and the pressure transducer
method. The OIT values thus obtained may be compared from should allow for fast pressure equilibrium to ensure accurate recording of
the pressure above the specimen during testing.
one hydrocarbon to another or to a reference material to obtain
relative oxidative stability information.
6.3.1.4 A Pressure Regulator, or similar device to adjust the
applied pressure in the test chamber to 60.2 MPa of the
5.2 Typical uses include the oxidative stability of edible oils
desired value.
and fats (oxidative rancidity), lubricants, greases, and polyole-
fins. 6.3.1.5 A Ballast, or similar means to maintain the applied
pressure in the test chamber constant to 60.2 MPa.
6. Apparatus
6.3.1.6 Valves, to control the gas in the test chamber or to
isolate components of the pressure system.
6.1 Differential Scanning Calorimeter or Pressure Differen-
tial Scanning Calorimeter, the essential instrumentation re-
6.4 Flow meter, capable of reading 50 mL/min or another
quired to provide the minimum differential scanning calorimet-
selected flow rate, accurate to within 6 5 %. Ensure the
ric capability for these test methods include:
flowmeter is calibrated for oxygen. Contact a supplier of flow
6.1.1 DSC Test Chamber, composed of:
meters for specific details on calibration, see Note 6, following
6.1.1.1 A Furnace(s), to provide uniform controlled heating
Section 11.4. (Warning—Use metal or fluoropolymer tubing
of a specimen and reference to a constant temperature or at a
with oxygen rather than the commonly used rubber or polyvi-
constant rate within the applicable temperature range of these
nyl chloride plastic tubing. There have been hazardous situa-
test methods.
tions with prolonged use of certain polymer tubing in oxygen
6.1.1.2 A Temperature Sensor, to provide an indication of
service.)
the specimen/furnace temperature to 60.4°C.
6.1.1.3 Differential Sensors, to detect a heat flow difference NOTE 5—Gas delivery tubing should be kept as short as possible to
minimize “dead” volume.
between specimen and reference with a sensitivity of 5 µW.
6.1.1.4 A means of sustaining a Test Chamber Environment
6.5 Analytical Balance with a capacity of at least 100 mg
of a purge gas of 50 mL/min within 5 %.
and capable of weighing to the nearest 0.01 mg or less than 1 %
6.1.2 Temperature Controller, capable of executing a spe-
of the specimen mass.
cific temperature program by operating the furnace(s) between
6.6 Specimen Containers, and sample holders are the alu-
selected temperature limits at a rate of temperature change of
minum sample pans and should be inert to the sample and the
40°C/min constant to 1 % and an isothermal temperature
oxidizing gas. The pans shall be clean, dry, and flat. A typical
constant to 60.4°C
cylindrical pan has the following dimensions: height, 1.5 to 2.5
NOTE 2—In certain cases when the sample under study is of high
mm and outer diameter, 5.0 to 6.0 mm.
volatility (for example, low molecular weight hydrocarbons), either the
6.6.1 New sample pans shall be cleaned by the procedure
use of pressures in excess of one atmosphere or lower temperatures may
be required. The operator is cautioned to verify (with apparatus manufac- found in Annex A1.
´1
E1858 − 08 (2015)
7. Materials 11.2 Place the uncovered prepared specimen in the sample
position of the instrument and an empty specimen pan, without
7.1 Oxygen, extra dry, purity of not less than 99.50 % by
lid, in the reference position. Be sure that the pans are centered
volume. (Warning—Oxidizer. Gas under pressure.)
on the sensors.
7.2 Indium, of not less than 99.9 % by mass.
11.3 Clean and replace all DSC covers in accordance with
7.3 Tin, of not less than 99.9 % by mass.
appropriate recommendations.
8. Precautions
11.4 Adjust flow rate of oxygen gas to 50.0 6 2 mL/min
8.1 Warning—Oxygen is a strong oxidizer and vigorously accurate to 64 %. Other flow rates may be used, but shall be
noted in the report.
accelerates combustion. Keep surfaces clean.
8.2 Warning—Oxygen is a strong oxidizer and may react
NOTE 8—Many flowmeters are not rated for high pressure operation and
with aluminum pans. may burst if excess pressure is applied. In these cases, the flow rate should
be measured at atmospheric pressure at the exit of the DSC cell, if
8.3 If the specimen is heated to decomposition, toxic or
recommended by the instrument manufacturer. If measured at elevated
corrosive products may be released.
pressure, the flow rate should be corrected to a comparable flow rate (for
example, 1.4 mL/min at 3.5 MPa).
8.4 For certain types of PDSC, it is recommended that the
flow be set up with a “reverse flow” implementation to ensure
11.5 Set the instrument sensitivity as required to retain the
there is no contact of decomposed hydrocarbons with incoming oxidation exotherm on the recorded range. A pre-analysis may
oxygen within the instrument. See instrument designer’s rec-
be required to determine this value. A sensitivity of 2 W/g full
ommendation on “reverse flow.” scale is typically acceptable.
11.6 Purge the specimen area for 3 to 5 min, to ensure
9. Sampling
exchange of air with oxygen at atmospheric pressure. Check
9.1 If the sample is a liquid or powder, mix thoroughly prior
the flow rate at elevated pressure and re-adjust to 50 6 2
to sampling.
mL/min, if required.
9.2 In the absence of information, samples are to be
11.7 Commence programmed heating at 40°C/min from
analyzed as received. If some heat or mechanical treatment is
ambient temperature to the isothermal temperatures, 175 or
applied to the sample prior to analysis, this treatment should be
195°C. Wait until temperature reaches isothermal conditions
in nitrogen and noted in the report. If some heat treatment is
and record the thermal curve.
used prior to oxidative testing, then record any mass loss as a
11.7.1 Continue heating until the isothermal test tempera-
result of the treatment.
ture 60.4°C is reached. Discontinue programmed heating and
10. Calibration
equilibrate sample at the constant isothermal temperature. Zero
time is recorded at the initiation of the OIT measurement and
10.1 Calibrate the temperature output of the instrument
includes time to heat from room temperature to the specified
using Test Method E967 except that a heating rate of 1°C/min
isothermal temperature. The OIT is the total time from the start
shall be used to approach the isothermal conditions of this test.
of the experiment at room temperature in oxygen to the
Use indium and tin calibration material to bracket the tempera-
extrapolated onset time of the exothermic process.
ture used in this test. Perform calibration under ambient
pressure conditions. 11.7.2 To ensure that the sample is at the proper test
temperature, it is suggested that the test temperature be read
NOTE 6—This assumes known temperature calibration with dependence
and reported at 5 min into the isothermal portion of the run.
on pressure. If the temperature calibration varies with pressure by more
than 0.4°C, then the calibration should be performed at the test pressure.
11.8 Test Methods:
10.2 Obtain the melting temperatures observed in the instru-
11.8.1 When using DSC Test Method A, maintain flow rate
ment calibration from extrapolated onset temperatures.
of 50 mL/min (see 11.6) of oxygen and isothermal temperature
of 195 6 0.4°C.
10.3 Confirm the time scale conformance of the differential
scanning calorimeter to better than 1 % using Test Method 11.8.2 When using PDSC Test Method B, pressurize slowly,
E1860.
adjust and maintain pressure of oxygen at 3.5 6 0.2 MPa,
maintain flow rate of 50 mL/min (see 11.6) and isothermal
11. Procedure
temperature of 1756 0.4°C.
11.1 Weigh 3.00 to 3.30 mg of sample to a precision of
11.8.3 Other temperatures in the range of 170 to 21
...

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 E1858 − 08 (Reapproved 2015)
Standard Test MethodMethods 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 ThisThese test method describesmethods 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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 ThisThese test method ismethods are related to ISO 11357–6 but is different in technical content. ThisThese test method
ismethods 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 health practices and determine the applicability of regulatory
limitations prior to use. Specific precautionary statements are given in Note 56.4 and Note 1311.10.
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
D5482 Test Method for Vapor Pressure of Petroleum Products (Mini Method—Atmospheric)
D5885 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
2.2 Other Standards:
ISO 11357–6 Plastice-Differential Scanning Calorimetry (DSC) — Part 6: Oxidation Induction Time
CEC L-85–T Hot Surface Oxidation
ThisThese test method ismethods 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 Sept. 1, 2008May 1, 2015. Published October 2008May 2015. Originally approved in 1997. Last previous edition approved in 20032008 as
E1858 – 03.E1858 – 08. DOI: 10.1520/E1858-08.10.1520/E1858-08R15E01.
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.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E1858 − 08 (2015)
3. Terminology
3.1 Definitions:
3.1.1 Specific technical terms used in thisthese test methodmethods are given in Terminology E473.
4. Summary of Test Method
4.1 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.
4.2 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 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.
5.2 Typical uses include the oxidative stability of edible oils and fats (oxidative rancidity), lubricants, greases, and polyolefins.
6. Apparatus
6.1 Differential Scanning Calorimeter or Pressure Differential Scanning Calorimeter, the essential instrumentation required to
provide the minimum differential scanning calorimetric capability for thisthese test methodmethods include:
6.1.1 DSC Test Chamber, composed of:
6.1.1.1 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 thisthese test method.methods.
6.1.1.2 A Temperature Sensor, to provide an indication of the specimen/furnace temperature to 60.4 °C.60.4°C.
6.1.1.3 Differential Sensors, to detect a heat flow difference between specimen and reference with a sensitivity of 5 μW.
6.1.1.4 A means of sustaining a Test Chamber Environment of a purge gas of 50 mL/min within 5 %.
6.1.2 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 °C40°C/min⁄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.
6.1.3 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.
6.2 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.
6.3 For use in Test Method B.
6.3.1 Pressure System, consisting of:
6.3.1.1 A Pressure Vessel, or similar means of sealing the test chamber at any applied oxygen pressure within the pressure limits
of thisthese test method.methods.
6.3.1.2 A source of pressurized oxygen or air capable of sustaining a regulated gas pressure in the test chamber of up to 3.2 MPa.
6.3.1.3 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.
6.3.1.4 A Pressure Regulator, or similar device to adjust the applied pressure in the test chamber to 60.2 MPa of the desired
value.
´1
E1858 − 08 (2015)
6.3.1.5 A Ballast, or similar means to maintain the applied pressure in the test chamber constant to 60.2 MPa.
6.3.1.6 Valves, to control the gas in the test chamber or to isolate components of the pressure system.
6.4 Flow 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 106, following Section 11.4.
(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—Caution: 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.
6.5 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.
6.6 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, 1.5 to 2.5 mm and outer
diameter, 5.0 to 6.0 mm.
6.6.1 New sample pans shall be cleaned by the procedure found in Annex A1.
7. Materials
7.1 Oxygen, extra dry, purity of not less than 99.50 % by volume. (Warning—Oxidizer. Gas under pressure.)
NOTE 7—Warning: Oxidizer. Gas under pressure.
7.2 Indium, of not less than 99.9 % by mass.
7.3 Tin, of not less than 99.9 % by mass.
8. Precautions
NOTE 8—Caution: Oxygen is a strong oxidizer and vigorously accelerates combustion. Keep surfaces clean.
8.1 Warning—Oxygen is a strong oxidizer and vigorously accelerates combustion. Keep surfaces clean.
NOTE 9—Caution: Oxygen is a strong oxidizer and may react with aluminum pans.
8.2 Warning—Oxygen is a strong oxidizer and may react with aluminum pans.
8.3 If the specimen is heated to decomposition, toxic or corrosive products may be released.
8.4 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.”
9. Sampling
9.1 If the sample is a liquid or powder, mix thoroughly prior to sampling.
9.2 In the absence of information, samples are to be analyzed as received. If some heat or mechanical treatment is applied to
the sample prior to analysis, this treatment should be in nitrogen and noted in the report. If some heat treatment is used prior to
oxidative testing, then record any mass loss as a result of the treatment.
10. Calibration
10.1 Calibrate the temperature output of the instrument using Test Method E967 except that a heating rate of 1 °C/min 1°C/min
shall be used to approach the isothermal conditions of this test. Use indium and tin calibration material to bracket the temperature
used in this test. Perform calibration under ambient pressure conditions.
NOTE 6—This assumes known temperature calibration with dependence on pressure. If the temperature calibration varies with pressure by more than
0.4 °C, 0.4°C, then the calibration should be performed at the test pressure.
10.2 Obtain the melting temperatures observed in the instrument calibration from extrapolated onset temperatures.
10.3 Confirm the time scale conformance of the differential scanning calorimeter to better than 1 % using Test Method E1860.
11. Procedure
11.1 Weigh 3.00 to 3.30 mg of sample to a precision of 6 0.01 60.01 mg into a clean specimen capsule. For accurate
comparisons, specimens should have equivalent masses to within 10 % to avoid mass-dependent effects on the oxidative properties.
Do not place lid on specimen pan or capsule.
NOTE 7—Other specimen sizes may be used if used consistently. However, the OIT values obtained may differ from those obtained with 3 mg. Also,
vented specimen covers may be used, but OIT values may differ from those obtained in open pans. The following procedure assumes the use of open
pans.
´1
E1858 − 08 (2015)
11.2 Place the uncovered prepared specimen in the sample position of the instrument and an empty specimen pan, without lid,
in the reference position. Be sure that the pans are centered on the sensors.
11.3 Clean and replace all DSC covers in accordance with appropriate recommendations.
11.4 Adjust flow rate of oxygen gas to 50.0 6 2 mL/min accurate to 6 4 %. 64 %. Other flow rates may be used, but shall
be noted in the report.
NOTE 8—Many flowmeters are not rated for high pressure operation and may burst if excess pressure is applied. In these cases, the flow rate should
be measured at atmospheric pressure at the exit of the DSC cell, if recommended by the instrument manufacturer. If measured at elevated pressure, the
flow rate should be corrected to a comparable flow rate (for example, 1.4 mL/min at 3.5 MPa).
11.5 Set the instrument sensitivity as required to retain the oxidation exotherm on the recorded range. A pre-analysis may be
required to determine this value. A sensitiv
...