ASTM D3850-94(2006)
(Test Method)Standard Test Method for Rapid Thermal Degradation of Solid Electrical Insulating Materials By Thermogravimetric Method (TGA)
Standard Test Method for Rapid Thermal Degradation of Solid Electrical Insulating Materials By Thermogravimetric Method (TGA)
SIGNIFICANCE AND USE
Thermogravimetry is useful in determining the dynamic functional effect of temperature on the amount of volatile materials leaving a specimen as the latter is heated progressively to higher temperatures. TGA can be useful for process control, process development, material evaluation, and for identification and quality control in specifications.
The thermal stability of a material can be associated with the degree and time rate of mass loss as a function of temperature. TGA curves can, therefore, be used as a preliminary screen method in the evaluation of relative behavior of insulating materials of the same generic family.
The functional temperature-life relationship of an insulating material in any given application depends on a number of service and environmental factors. Therefore, the information obtained from TGA curves is not adequate by itself to describe the thermal capability of an insulating material.
Refer to the Appendix for further discussion of the interpretation of TGA data.
SCOPE
1.1 This test method outlines a procedure for obtaining thermogravimetric (TGA) data on solid polymeric materials intended for use as electrical insulating materials.
1.2 Do not use this standard to quantify an estimate of the long-term thermal capability for any electrical insulating material. If a relationship exists between TGA and the long-term thermal capabilities of a material, then that fact must be established and made public, preferably by comparing data between a candidate and another material known to display similar failure modes.
1.3 The values stated in SI units are the standard.
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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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An American National Standard
Designation:D3850–94 (Reapproved 2006)
Standard Test Method for
Rapid Thermal Degradation of Solid Electrical Insulating
Materials By Thermogravimetric Method (TGA)
This standard is issued under the fixed designation D3850; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E1582 Practice for Calibration of Temperature Scale for
Thermogravimetry
1.1 This test method outlines a procedure for obtaining
thermogravimetric (TGA) data on solid polymeric materials
3. Terminology
intended for use as electrical insulating materials.
3.1 Definitions—Definitions are in accordance with Termi-
1.2 Do not use this standard to quantify an estimate of the
nology D883, Terminology D1711, and Terminology E473.
long-term thermal capability for any electrical insulating ma-
3.2 Abbreviations:Abbreviations—Abbreviations are in ac-
terial. If a relationship exists between TGA and the long-term
cordancewithTerminologyD1600,unlessotherwiseindicated.
thermal capabilities of a material, then that fact must be
established and made public, preferably by comparing data
4. Summary of Test Method
between a candidate and another material known to display
4.1 This thermogravimetric technique uses the record of the
similar failure modes.
mass loss versus the temperature of the specimen during the
1.3 The values stated in SI units are the standard.
time of exposure to a specified prescribed environment using a
1.4 This standard does not purport to address all of the
controlled time rate of heating.
safety concerns, if any, associated with its use. It is the
4.2 The record is a TGAcurve, with percent of initial mass
responsibility of the user of this standard to establish appro-
astheordinateandtemperatureastheabscissa(seeFigs.1and
priate safety and health practices and determine the applica-
2).
bility of regulatory limitations prior to use.
4.3 The temperature is measured and recorded at specified
masslosspoints(recordedasaTGAcurve),usinganelectronic
2. Referenced Documents
2 chart recorder or other suitable data acquisition device.
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
5. Significance and Use
D1600 Terminology for Abbreviated Terms Relating to
5.1 Thermogravimetryisusefulindeterminingthedynamic
Plastics
functional effect of temperature on the amount of volatile
D1711 Terminology Relating to Electrical Insulation
materials leaving a specimen as the latter is heated progres-
D2307 Test Method for Thermal Endurance of Film-
sively to higher temperatures. TGA can be useful for process
Insulated Round Magnet Wire
control, process development, material evaluation, and for
E220 Test Method for Calibration of Thermocouples By
identification and quality control in specifications.
Comparison Techniques
5.2 The thermal stability of a material can be associated
E473 Terminology Relating to Thermal Analysis and Rhe-
with the degree and time rate of mass loss as a function of
ology
temperature. TGAcurves can, therefore, be used as a prelimi-
nary screen method in the evaluation of relative behavior of
This test method is under the jurisdiction of ASTM Committee D09 on
insulating materials of the same generic family.
Electrical and Electronic Insulating Materials and is the direct responsibility of
5.3 The functional temperature-life relationship of an insu-
Subcommittee D09.17 on Thermal Capabilities.
lating material in any given application depends on a number
Current edition approved April 1, 2006. Published April 2006. Originally
of service and environmental factors. Therefore, the informa-
approved in 1979. Last previous edition approved in 2000 as D3850–94(2000).
DOI: 10.1520/D3850-94R06.
tion obtained from TGA curves is not adequate by itself to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
describe the thermal capability of an insulating material.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.4 Refer to the Appendix for further discussion of the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. interpretation of TGA data.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3850–94 (2006)
Sample 8.54 mg Heating Rate 5 °C/min Purging Gas Flow 0.8 mL/s
FIG. 1 Curve No. 1, Typical TGA for Polyester Film
Sample 5.93 mg Heating Rate 5 °C/min Purging Gas Flow 0.8 mL/s
FIG. 2 Curve No. 2, Typical TGA for Polyimide Film
6. Apparatus 6.1.4 Suitable Data Acquisition Device, and
6.1 Thermogravimetric Analyzer—A system of related in- 6.1.5 Supply of Purging Gas.
struments comprising:
NOTE 1—For many applications, the purging gas is nitrogen or air
6.1.1 Microbalance, of the null type, sensitive to 0.001 mg,
having a dew point of at or below−10 °C.
6.1.2 Furnace, controllable at a constant rate over a tem-
perature range of interest, typically 25 to 1000 °C,
7. Sampling
6.1.3 Temperature Programmer, capable of providing a
7.1 Usesamplingplansasdescribedinspecificationsortest
linear rate of rise of the furnace at a predetermined value
methods specific to individual electrical insulating materials.
(normally 5 °C/min) with a tolerance of 6 0.1 °C/min,
D3850–94 (2006)
8. Test Specimens 10.1.2 Curing time and temperature in the case of resin
specimens,
8.1 Prepare test specimens in accordance with the test
10.1.3 Mass, approximate dimensions and form (for ex-
method applicable to the material under investigation.
ample, film, laminate, molded) of the specimen,
8.2 Generally, it is found that specimens of 2 to 20 mg are
10.1.4 Heating rate,
satisfactory,dependingontheconfigurationandtestapparatus.
10.1.5 Rate of flow and type of gas used for purging,
Test results depend in part on the size and shape of specimen,
10.1.6 TGA curve of material evaluated, and
due to thermal equilibrium and diffusion effects.
10.1.7 Temperatures at which losses of initial specimen
8.3 When the specimen is a coating on a substrate, the total
mass, if obtained, of 10, 20, 30, 50, and 75% occur.
mass may be substantially greater, because of the mass
contribution of the substrate material.
NOTE 3—Do not list temperatures that exceed the resolution of the
instrumentation. Normally this is not to be greater than 2.5 °C. Report the
9. Procedure
resolution.
9.1 Calibrate the balance at full scale to within 6 0.01 mg,
11. Precision and Bias
following the recommended procedure.
9.2 Calibrate the temperature-sensing system to within 6 1
11.1 Thistestmethodisbasedonthedynamicmeasurement
°C(seeMethodE220),followingtherecommendedprocedure. of mass loss as a function of increasing temperature. Devia-
9.2.1 Position the temperature sensor to prevent contact
tions in results that affect precision are caused by variations in
with specimens which may become distorted during heating. a number of complex factors (for example, physical irregulari-
9.2.2 Temperature calibration is critical and the method
ties of the specimen, variations in the purging gas composition
employedwillvarywiththeapparatus.Calibrateinaccordance and flow characteristics) and ge
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