ASTM D3895-07
(Test Method)Standard Test Method for Oxidative-Induction Time of Polyolefins by Differential Scanning Calorimetry
Standard Test Method for Oxidative-Induction Time of Polyolefins by Differential Scanning Calorimetry
SIGNIFICANCE AND USE
The OIT is a qualitative assessment of the level (or degree) of stabilization of the material tested. This test can be used as a quality control measure to monitor the stabilization level in formulated resin as received from a supplier, prior to extrusion.
Note 2—The OIT measurement is an accelerated thermal-aging test and as such can be misleading. Caution should be exercised in data interpretation since oxidation reaction kinetics are a function of temperature and the inherent properties of the additives contained in the sample. For example, OIT results are often used to select optimum resin formulations. Volatile antioxidants may generate poor OIT results even though they may perform adequately at the intended use temperature of the finished product.
Note 3—There is no accepted sampling procedure, nor have any definitive relationships been established for comparing OIT values on field samples to those on unused products, hence the use of such values for determining life expectancy is uncertain and subjective.
SCOPE
1.1 This test method outlines a procedure for the determination of oxidative-induction time (OIT) of polymeric materials by differential scanning calorimetry (DSC). It is applicable to polyolefin resins that are in a fully stabilized/compounded form.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 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 hazards information is given in Section 8. Note 1
This test method is similar to ISO 11357-6, but not equivalent. ISO procedure provides additional information not supplied by this test method.
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Standards Content (Sample)
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Designation:D3895 −07
StandardTest Method for
Oxidative-Induction Time of Polyolefins by Differential
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Scanning Calorimetry
This standard is issued under the fixed designation D3895; 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* 3.2 Definitions of Terms Specific to This Standard:
3.2.1 oxidative induction time—a relative measure of a
1.1 This test method outlines a procedure for the determi-
material’s resistance to oxidative decomposition; it is deter-
nation of oxidative-induction time (OIT) of polymeric materi-
mined by the thermoanalytical measurement of the time
als by differential scanning calorimetry (DSC). It is applicable
interval to onset of exothermic oxidation of a material at a
to polyolefin resins that are in a fully stabilized/compounded
specified temperature in an oxygen atmosphere.
form.
3.2.2 Abbreviations:
1.2 The values stated in SI units are to be regarded as the
3.2.3 HDPE—high-density polyethylene.
standard.
3.2.4 LDPE—low-density polyethylene.
1.3 This standard does not purport to address all of the
3.2.5 LLDPE—linear low-density polyethylene.
safety concerns, if any, associated with its use. It is the
3.2.6 OIT—oxidative induction time.
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific hazards
4.1 The sample to be tested and the reference material are
information is given in Section 8.
heated at a constant rate in an inert gaseous environment
(nitrogen). When the specified temperature has been reached,
NOTE 1—This test method is similar to ISO 11357–6, but not equiva-
lent. ISO procedure provides additional information not supplied by this the atmosphere is changed to oxygen maintained at the same
test method.
flow rate. The specimen is then held at constant temperature
until the oxidative reaction is displayed on the thermal curve.
2. Referenced Documents
The time interval from when the oxygen flow is first initiated
2
2.1 ASTM Standards:
to the oxidative reaction is referred to as the induction period.
D4703 Practice for Compression Molding Thermoplastic
4.1.1 The end of the induction period is signaled by an
Materials into Test Specimens, Plaques, or Sheets
abrupt increase in the specimen’s evolved heat or temperature
E473 Terminology Relating to Thermal Analysis and Rhe-
and may be observed by a differential scanning calorimeter
ology
(DSC). The OIT is determined from the data recorded during
E691 Practice for Conducting an Interlaboratory Study to
the isothermal test.
Determine the Precision of a Test Method
4.2 The type of containment system used depends on the
E967 Test Method for Temperature Calibration of Differen-
intended application use of the material being tested. Polyole-
tial Scanning Calorimeters and Differential Thermal Ana-
finsusedinthewireandcableindustrytypicallyrequirecopper
lyzers
or aluminum pans, whereas polyolefins used in geomembrane
and vapor-barrier film applications exclusively use aluminum
3. Terminology
pans.
3.1 Definitions—Definitions of terms applying to thermal
4.3 Unless otherwise specified, the analysis temperature
analysis appear in Terminology E473.
usedinthistesthasbeensetarbitrarilyat200.0°C.Forsamples
that have relatively low or high stabilization levels, a different
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This test method is under the jurisdiction ofASTM Committee D20 on Plastics
temperature may be selected (typically between 180 and
and is the direct responsibility of Subcommittee D20.30 on Thermal Properties.
220°C) to yield a thermal curve that can be interpreted and
Current edition approved April 1, 2007. Published April 2007. Originally
approved in 1980. Last previous edition approved in 2006 as D3895 – 06. DOI: analyzed easily.
10.1520/D3895-07.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 5. Significance and Use
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1 The OIT is a qualitative assessment of the level (or
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. degree) of stabilization of the material tested. This test can be
*A Summary of Changes section appears at the end of this standard
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D3895−07
used as a quality control measure to monitor the stabilization 6.12 Thickness Gage.
level in formulated resin as received from a suppli
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