ASTM E487-20

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Designation: E487 − 14 E487 − 20
Standard Test MethodMethods for
Constant-Temperature Stability of Chemical Materials
This standard is issued under the fixed designation E487; 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
1.1 ThisThese test method describesmethods describe the assessment of constant-temperature stability (CTS) of chemical
materials that undergo exothermic reactions. The techniques and apparatus described may be used on solids, liquids, or slurries of
chemical substances.
1.2 When a series of materials is tested by thisthese test method,methods, the results permit ordering the materials relative to
each other with respect to their thermal stability.
1.3 Limitations of Test:
1.3.1 ThisThese test method ismethods are limited to ambient temperatures and above.
1.3.2 ThisThese test method determinesmethods determine neither a safe storage temperature nor a safe processing temperature.
NOTE 1—A safe storage or processing temperature requires that any heat produced by a reaction be removed as fast as generated and that proper
consideration be given to hazards associated with reaction products.
1.3.3 When thisthese test method ismethods are used to order the relative thermal stability of materials, the tests must be run
under the same confinement condition (see 8.3).
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 This standard should be used to measure and describe the properties of materials, products, or assemblies in response to
heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk
of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire
risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular
end use.
1.6 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all
of the safety problems concerns, if any, associated with its use. It is the responsibility of whoever uses the user of this standard
to consult and establish appropriate safety safety, health, and healthenvironmental practices and determine the applicability of
regulatory limitations prior to use.
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:
E473 Terminology Relating to Thermal Analysis and Rheology
E537 Test Method for The Thermal Stability of Chemicals by Differential Scanning Calorimetry
E967 Test Method for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers
E968 Practice for Heat Flow Calibration of Differential Scanning Calorimeters
E1445 Terminology Relating to Hazard Potential of Chemicals
E1860 Test Method for Elapsed Time Calibration of Thermal Analyzers
ThisThese test method ismethods are under the jurisdiction of ASTM Committee E27 on Hazard Potential of Chemicals and is the direct responsibility of E27.02 on
Thermal Stability and Condensed Phases.
Current edition approved March 1, 2014Feb. 1, 2020. Published March 2014February 2020. Originally approved in 1974. Last previous edition approved in 20092014
as E487 – 09.E487 – 14. DOI: 10.1520/E0487-14.10.1520/E0487-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’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
E487 − 20
3. Terminology
3.1 Definitions:
3.1.1 constant-temperature stability (CTS) value—the maximum temperature at which a chemical compound or mixture may be
held for a 120-min period under the conditions imposed in this test without exhibiting a measurable exothermic reaction.
3.1 The specialized terms in this standard are described in Terminologies E473 and E1445 including differential scanning
calorimetry, differential thermal analysis, exotherm, and first-deviation-from-baseline.Definitions:
3.1.1 The specialized terms in this standard are described in Terminologies E473 and E1445, including differential scanning
calorimetry, differential thermal analysis, exotherm, and first-deviation-from-baseline.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 constant-temperature stability (CTS) value, n—the maximum temperature at which a chemical compound or mixture may
be held for a 120-min period under the conditions imposed in this test without exhibiting a measurable exothermic reaction.
4. Summary of Test MethodMethods
4.1 A sample of the chemical compound or mixture is placed in a glass or metal tube that is heated to a test temperature of
interest. The sample temperature and heat flow or the difference between the sample temperature and the temperature of an inert
reference material, are monitored over a 120-min period or until an exothermic reaction is recorded. Test temperatures are
decreased in 10°C 10 °C intervals until no exothermic reaction is observed in the 120-min test period. The Constant Temperature
Stability constant-temperature stability is determined and reported using either Test Method A or Test Method B.
NOTE 2—Test periods other than two 120-min periods may be used but shall be reported.
NOTE 3—The processing times in many industrial scale unit operations (for example, drying, distillations, and the like) normally significantly exceed
the 120-min time period in this CTS test procedure. Therefore, for the effective application of the CTS data for industrial scale operations, the CTS time
must be extended to be greater than the processing time in the actual operation.
5. Significance and Use
5.1 This test method is a These test methods are useful adjunct to dynamic thermal tests that are performed under conditions
in which the sample temperature is increased continuously at a programmed rate. Results obtained under dynamic test conditions
present difficulties in determining the temperature at which an exotherm initiates because onset temperature is dependent on
heating rate. TheThese test method describedmethods describe in the present standard attempts to determine the onset temperature
under isothermal conditions where the heating rate is zero.
6. Apparatus
6.1 The design and complexity of the apparatus required for this method depends upon the size of the sample to be used. In
general, observance of an exothermic reaction in small samples (less than 50 mg) is best done using differential thermal analysis
or differential scanning calorimetry equipment and techniques. Larger samples (up to 2 g) may be tested using a Kuhner Micro
CTS apparatus.
6.2 The following items are required to obtain the appropriate experimental data:
6.2.1 A test chamber composed of:
6.2.1.1 Furnace(s), to provide uniform controlled heating of a specimen and reference to a constant temperature.
6.2.1.2 Temperature Sensor, to provide an indication of the specimen/furnace temperature to 60.1°C. 60.1 °C.
6.2.1.3 Differential Sensor, to detect a difference in heat flow or temperature between specimen and reference specimen
equivalent to 1 mW or 40 mK.
NOTE 4—Sample temperature may be measured either absolutely or differentially. When differential temperature measurements are made, and a
reference material is used, the reference material should match the physical state and heat capacity of the sample as closely as practical. Typical reference
materials are calcined aluminum oxide, glass beads, silicone oils, and a combination of these.
NOTE 5—Commercially available differential thermal analysis or differential scanning calorimetry apparatus capable of operating in an isothermal mode
may be used. Alternatively, the apparatus may be assembled or fabricated from commercially available components (see 12.1).
6.2.2 A temperature Controller capable of heating from ambient to 400°C 400 °C at a rate of 1°C/min to 50°C/min 1 °C/min
to 50 °C/min and maintaining an isothermal temperature constant within that range to 61°C 61 °C for 120 min.
6.2.3 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 differential scanning calorimetry are heat flow, temperature and time.
6.2.4 Containers (pans, crucibles, vials, test tubes, etc.) which are inert to the specimen and reference material and which are
of suitable structure, shape, and integrity to contain the specimen and reference in accordance with the temperature and specimen
mass requirements described in this section.
6.3 A Balance with a capacity of 100 mg or more to weigh specimens and/oror containers (pans, crucibles, vials, and the like)
like), or both, readable to 60.1 mg (see Note 6).
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7. Hazards
7.1 Dynamic thermal tests are normally carried out on small samples before the present test is undertaken. Therefore,
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