ASTM D3045-18

Standard Practice for Heat Aging of Plastics Without Load

SIGNIFICANCE AND USE
4.1 The use of this practice presupposes that the failure criteria selected to evaluate materials (that is, the property or properties being measured as a function of exposure time) and the duration of the exposure can be shown to relate to the intended use of the materials.  
4.2 Plastic materials exposed to heat are subject to many types of physical and chemical changes. The severity of the exposures in both time and temperature determines the extent and type of change that takes place. A plastic material is not necessarily degraded by exposure to elevated temperatures. However, extended periods of exposure of plastics to elevated temperatures will generally cause some degradation, with progressive changes in physical properties. Specific properties and failure (or lifetime) criteria for these properties are typically chosen for the evaluation of thermal endurance.  
4.3 Generally, short exposures at elevated temperatures drive out volatiles such as moisture, solvents, or plasticizers, relieve molding stresses, advance the cure of thermosets, and may cause some change in color of the plastic or coloring agent, or both. Normally, additional shrinkage should be expected with loss of volatiles or advance in polymerization.  
4.4 Some plastic materials become brittle due to loss of plasticizers after exposure at elevated temperatures. Other types of plastics become soft and sticky, either due to sorption of volatilized plasticizer or due to breakdown of the polymer.  
4.5 The degree of change observed will depend on the property measured. Different properties, mechanical or electrical, may not change at the same rate. For instance, the arc resistance of thermosetting compounds improves up to the carbonization point of the material. Mechanical properties, such as flexural properties, are sensitive to heat degradation and may change at a more rapid rate. Ultimate properties such as strength or elongation are more sensitive to degradation than bulk properties such as...
SCOPE
1.1 This practice is intended to define the exposure conditions for evaluating the thermal endurance of plastics when exposed solely to hot air for extended periods of time. Only the procedure for heat exposure is specified. The effect of elevated temperature on any particular property is determined by selection of the appropriate test method and test specimens for that property.  
1.2 This practice can be used as a guide to compare thermal aging characteristics of materials as measured by the change in some property of interest. The property of interest is measured at room temperature.  
1.3 This practice recommends procedures for comparing the thermal aging characteristics of materials at a single temperature. Recommended procedures for determining the thermal aging characteristics of a material using a series of elevated temperatures for the purpose of estimating endurance time to a defined property change at a lower temperature are also described; the applicability of the Arrhenius relation for making predictions to other temperatures, is assumed in this case.  
1.4 This practice does not predict thermal aging characteristics where interactions between stress, environment, temperature, and time control failure occur.  
1.5 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.
Note 1: This standard and ISO-2578 address the same subject matter but differ in technical content.  
1.6 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 ...

General Information

• Status: Published
• Publication Date: 31-Jul-2018
• ICS: 83.080.01 - Plastics in general
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.50 - Durability of Plastics

Relations

• Replaces: ASTM D3045-92(2010) - Standard Practice for Heat Aging of Plastics Without Load
• Effective Date: 01-Aug-2018
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM E145-19 - Standard Specification for Gravity-Convection and Forced-Ventilation Ovens
• Effective Date: 01-Mar-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM E456-13ae1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013

Overview

ASTM D3045-18 is a standard practice published by ASTM International that defines procedures for the heat aging of plastic materials without the application of external load. Its primary purpose is to establish uniform conditions for exposing plastic specimens to hot air, allowing the evaluation and comparison of a material’s thermal endurance. This practice is essential for understanding how plastics behave and potentially degrade when subjected to extended periods at elevated temperatures.

Heat aging tests guided by ASTM D3045-18 do not directly apply mechanical loads to the specimens. Instead, they focus on changes in various physical, mechanical, or electrical properties resulting from exposure to heat alone. This makes the standard a crucial tool for manufacturers, designers, and quality control professionals working with polymers in environments where elevated temperatures are a concern.

Key Topics

• Thermal Endurance Evaluation: Provides standardized exposure conditions enabling the assessment of how plastic materials change physically and chemically over time when exposed solely to hot air.

• Failure Criteria and Property Measurement: Requires that users select and document specific failure criteria-such as changes in strength, flexibility, color, or electrical properties-to relate heat aging results to intended product usage.

• Single and Multiple Temperature Protocols: Details procedures for long-term exposure at a single temperature and for using a series of temperatures to estimate thermal endurance, including the application of the Arrhenius relation for lifetime prediction.

• Cautions and Limitations: Addresses the complexity of heat aging, such as potential changes in material behavior across temperature thresholds and the impact of oven environment (humidity, air velocity). Clarifies that stress-environment-time interactions are not within this standard’s scope.

• Testing and Reporting Requirements: Specifies standardized test specimen preparation, conditioning, and exposure, as well as comprehensive reporting of methodology and results.

Applications

• Material Comparison and Selection: Enables designers and engineers to compare different plastic formulations in terms of their resistance to heat-induced aging, aiding in the selection of materials for applications like electrical insulation, automotive parts, or consumer products.

• Quality Control and Assurance: Provides consistent methods for manufacturers to evaluate production lot consistency or the impact of new additives or processing changes on thermal stability.

• Research and Product Development: Supports R&D activities by furnishing a reliable framework to assess heat resistance, study degradation mechanisms, and optimize product formulations for longer service life.

• Regulatory Compliance and Documentation: Helps organizations demonstrate due diligence in material testing and provides traceable documentation for regulatory agencies or end-users requiring proof of material performance under heat exposure.

Related Standards

• ISO 2578: International standard for the determination of time-temperature limits after exposure to prolonged action of heat on plastics. While closely related, there are noted technical differences from ASTM D3045.

• ASTM D618: Practice for conditioning plastics for testing, cited for specimen preparation and conditioning requirements.

• ASTM D883: Terminology relating to plastics, ensuring clarity and consistency in definitions used throughout plastic testing methodologies.

• ASTM D5423: Specification for forced-convection laboratory ovens, relevant for oven selection and operation in heat aging protocols.

• ISO 9080: Standard for determining the long-term hydrostatic strength of thermoplastic materials, providing guidance that complements the heat aging evaluations in D3045.

By using ASTM D3045-18, organizations can confidently evaluate the heat aging characteristics of plastics, improve material selection, and ensure long-term product durability in high-temperature environments. This standard is a valuable reference for anyone involved in plastics engineering, materials testing, or product certification.

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: D3045 − 18
Standard Practice for
Heat Aging of Plastics Without Load
This standard is issued under the fixed designation D3045; 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 U.S. Department of Defense.
1. Scope* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This practice is intended to define the exposure condi-
tions for evaluating the thermal endurance of plastics when
2. Referenced Documents
exposedsolelytohotairforextendedperiodsoftime.Onlythe
2.1 ASTM Standards:
procedure for heat exposure is specified.The effect of elevated
D618Practice for Conditioning Plastics for Testing
temperature on any particular property is determined by
D883Terminology Relating to Plastics
selection of the appropriate test method and test specimens for
D5374TestMethodsforForced-ConvectionLaboratoryOv-
that property.
ens for Evaluation of Electrical Insulation
1.2 Thispracticecanbeusedasaguidetocomparethermal
D5423Specification for Forced-Convection Laboratory Ov-
agingcharacteristicsofmaterialsasmeasuredbythechangein
ens for Evaluation of Electrical Insulation
some property of interest.The property of interest is measured
E145Specification for Gravity-Convection and Forced-
at room temperature.
Ventilation Ovens
1.3 Thispracticerecommendsproceduresforcomparingthe E456Terminology Relating to Quality and Statistics
thermal aging characteristics of materials at a single tempera-
2.2 ISO Standards:
ture. Recommended procedures for determining the thermal
ISO 2578(1993) Determination of Time-Temperature Lim-
aging characteristics of a material using a series of elevated
its After Exposure to Prolonged Action of Heat
temperatures for the purpose of estimating endurance time to a
ISO 9080(2012) Plastic Piping and Ducting Systems—
defined property change at a lower temperature are also
Determination of the Long-Term Hydrostatic Strength of
described; the applicability of the Arrhenius relation for
Thermoplastic Materials in Pipe Form by Extrapolation
making predictions to other temperatures, is assumed in this
3. Terminology
case.
3.1 General—The terminology given in Terminology D883
1.4 This practice does not predict thermal aging character-
andTerminology E456 is applicable to this practice.Terminol-
istics where interactions between stress, environment,
ogy not in place is defined in 3.2.
temperature, and time control failure occur.
1.5 This standard does not purport to address all of the 3.2 Definitions:
3.2.1 continuous use temperature (CUT)—the temperature
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- indegreesCelsiuscorrespondingtoagiventhermalendurance
time for a given failure criterion (typically 50% reduction in
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. property), derived from the Arrhenius relation of endurance
time and temperature, determined by heat aging at several
NOTE 1—This standard and ISO-2578 address the same subject matter
elevated temperatures. Several CUT values can exist, one for
but differ in technical content.
each property, endurance time and endurance criterion.
1.6 This international standard was developed in accor-
3.2.1.1 Discussion—In practice, the continuous use tem-
dance with internationally recognized principles on standard-
perature for a plastic, involves other environmental consider-
ization established in the Decision on Principles for the
ations as discussed elsewhere in this standard, than thermal
Development of International Standards, Guides and Recom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
is the direct responsibility of Subcommittee D20.50 on Durability of Plastics. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Aug. 1, 2018. Published August 2018. Originally the ASTM website.
approved in 1974. Last previous edition approved in 2010 as D3045–92(2010). Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/D3045-18. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3045 − 18
endurance alone. The term, CUT, used here, is intended as an γ transitions. These transitions should be avoided both in the
index for thermal endurance alone. The use of this term is rangeofagingtemperaturesused,aswellasinextrapolationof
found in automotive applications of plastics. The endurance the lifeline.Arrhenius principles may only be used to acceler-
time used for the CUT value reported should be specified as ate a chemical mechanism if there are no fundamental changes
CUT (endurance time). in the material properties. With semi-crystalline and highly
crystalline polymers, elevated temperatures may cause signifi-
3.2.2 temperature index (TI), also referred to as thermal
cantchangestothemorphologyofthematerial,invalidatingor
index (TI)—the temperature in degrees Celsius corresponding
compromising that assumption.
to an endurance time of 20,000 hours for a given failure
criterion (typically 50% reduction in property), derived from
NOTE 2—Caution should be exercised in using the Arrhenius relation
the Arrhenius relation of endurance time and temperature, and knowledge of physical changes in the material at elevated tempera-
turesisimportant.GuidancegiveninISO9080forcharacterizinglifetime
usually determined by heat aging at several elevated tempera-
ofplasticmaterialsinpipeformbyextrapolationsuggeststhatthehighest
tures.
oven aging temperature should be at least 15°C lower than the Vicat
3.2.2.1 Discussion—The TI can thus be seen as a special
softening temperature for glassy amorphous polymers, and at least 15°C
caseofCUTwheretheendurancetimeisfixedat20,000hours.
lower than the melting point for semi-crystalline polymers.
Agivenplasticmaterialandpropertyanditsretentioncriterion
4.7 Effects of exposure can be quite variable, especially
maybecharacterizedbyseveralCUTtimes,forexample,CUT
whenspecimensareexposedforlongintervalsoftime.Factors
(1000 hours), CUT (5000 hours), etc. as needed per require-
that affect the reproducibility of data are the degree of
ments of different applications. Further, several TI values can
temperature control of the enclosure, humidity of the oven, air
exist, one for each property and endurance criterion.
velocity over the specimen, and period of exposure. Errors in
4. Significance and Use exposure are cumulative with time. Certain materials are
susceptible to the influence of humidity.
4.1 The use of this practice presupposes that the failure
criteria selected to evaluate materials (that is, the property or
4.8 Itisnottobeinferredthatcomparativematerialranking
properties being measured as a function of exposure time) and is undesirable or unworkable. On the contrary, this practice is
the duration of the exposure can be shown to relate to the
designed to provide data which can be used for such compara-
intended use of the materials. tive purposes. However, the data obtained from this practice,
since it does not account for the influence of stress or
4.2 Plastic materials exposed to heat are subject to many
environment that is involved in most real life applications,
types of physical and chemical changes. The severity of the
must be used cautiously by the designer, who must inevitably
exposures in both time and temperature determines the extent
make material choices using additional data such as creep and
and type of change that takes place. A plastic material is not
creep rupture that are consistent with the requirements of the
necessarily degraded by exposure to elevated temperatures.
specific application.
However, extended periods of exposure of plastics to elevated
temperatures will generally cause some degradation, with
4.9 It is possible for many CUT and TI values to exist.
progressive changes in physical properties. Specific properties
Therefore, for any application of the CUT or the TI (tempera-
and failure (or lifetime) criteria for these properties are
ture index) to be valid, either the thermal aging program must
typically chosen for the evaluation of thermal endurance.
duplicate the intended thermal exposure conditions of the end
product, or the Arrhenius relation must apply.
4.3 Generally, short exposures at elevated temperatures
drive out volatiles such as moisture, solvents, or plasticizers,
4.10 TherecanbeverylargeerrorswhenArrheniusplotsor
relieve molding stresses, advance the cure of thermosets, and
equations based on data from experiments at a series of
may cause some change in color of the plastic or coloring
temperatures are used to estimate time to produce a defined
agent, or both. Normally, additional shrinkage should be
property change at some lower temperature. This estimate of
expected with loss of volatiles or advance in polymerization.
time to produce the property change or “failure” at the lower
temperature is often called the “service life;” however, using
4.4 Some plastic materials become brittle due to loss of
this term should be avoided as this implies the tester has
plasticizers after exposure at elevated temperatures. Other
information on specific failure criteria in end-use, while
types of plastics become soft and sticky, either due to sorption
numerous factors are not under the scope of this test. It is
of volatilized plasticizer or due to breakdown of the polymer.
preferable to use terms such as “end point,” “thermal endur-
4.5 The degree of change observed will depend on the
ance time,” and such. Because of the errors associated with
property measured. Different properties, mechanical or
thesecalculations,thisendurancetimeshouldbeconsideredas
electrical, may not change at the same rate. For instance, the
“maximum expected” rather than “typical.”
arc resistance of thermosetting compounds improves up to the
carbonization point of the material. Mechanical properties,
5. Apparatus
such as flexural properties, are sensitive to heat degradation
and may change at a more rapid rate. Ultimate properties such 5.1 Provisions for conditioning at specified standard condi-
tions.
asstrengthorelongationaremoresensitivetodegradationthan
bulk properties such as modulus, in most cases.
5.2 Oven—Acontrolled horizontal or vertical air flow oven,
4.6 The material studied can change inherent behavior with employing forced-draft circulation with substantial constant
change in temperature as for example when crossing α, β, and fresh air intake is recommended.To harmonize with ISO 2578
D3045 − 18
and IEC standards, it is preferable to use ovens that comply 8.3 If possible, avoid simultaneous aging of mixed groups
with the set temperature, temperature variation and air change ofdifferentcompoundswhichmightcausecrosscontamination
requirements of Specification D5423 as evaluated by the test from off-gassing during heat aging.
methods of Test Methods D5374. Alternatively, Specification
E145 may be used, with Specification E145, Type IIB ovens
9. Procedu
...

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.
Designation: D3045 − 92 (Reapproved 2010) D3045 − 18
Standard Practice for
Heat Aging of Plastics Without Load
This standard is issued under the fixed designation D3045; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Scope*
1.1 This practice is intended to define the exposure conditions for testingevaluating the resistance thermal endurance of plastics
to oxidation or other degradation when exposed solely to hot air for extended periods of time. Only the procedure for heat exposure
is specified, not the test method or specimen. specified. The effect of heat elevated temperature on any particular property may be
is determined by selection of the appropriate test method and specimen.test specimens for that property.
1.2 This practice can be used as a guide to compare thermal aging characteristics of materials as measured by the change in
some property of interest. The property of interest is measured at room temperature.
1.3 This practice should be used as a guide to compare thermal aging characteristics of materials as measured by the change
in some property of interest. This practice recommends procedures for comparing the thermal aging characteristics of materials
at a single temperature. Recommended procedures for determining the thermal aging characteristics of a material atusing a series
of elevated temperatures for the purpose of estimating endurance time to a defined property change at somea lower temperature
are also described.described; the applicability of the Arrhenius relation for making predictions to other temperatures, is assumed
in this case.
1.4 This practice does not predict thermal aging characteristics where interactions between stress, environment, temperature,
and time control failure occurs.occur.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—ISO-2578 is considered to be technically equivalent to this practice.This standard and ISO-2578 address the same subject matter but differ
in technical content.
1.6 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:
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1870D5374 Practice for Elevated Temperature Aging Using a Tubular OvenTest Methods for Forced-Convection Laboratory
Ovens for Evaluation of Electrical Insulation (Withdrawn 1998)
D1898D5423 Practice for Sampling of PlasticsSpecification for Forced-Convection Laboratory Ovens for Evaluation of
Electrical Insulation (Withdrawn 1998)
E145 Specification for Gravity-Convection and Forced-Ventilation Ovens
E456 Terminology Relating to Quality and Statistics
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.50 on Durability of Plastics.
Current edition approved March 15, 2010Aug. 1, 2018. Published June 2010August 2018. Originally approved in 1974. Last previous edition approved in 20032010 as
D3045 – 92 (2003).(2010). DOI: 10.1520/D3045-92R10.10.1520/D3045-18.
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3045 − 18
2.2 ISO Standard:Standards:
ISO 2578 (1974)(1993) Determination of Time-Temperature Limits After Exposure to Prolonged Action of Heat
ISO 9080 (2012) Plastic Piping and Ducting Systems—Determination of the Long-Term Hydrostatic Strength of Thermoplastic
Materials in Pipe Form by Extrapolation
3. Terminology
3.1 General—The terminology given in Terminology D883 and Terminology E456 is applicable to this practice. Terminology
not in place is defined in 3.2.
3.2 Definitions:
3.2.1 continuous use temperature (CUT)—the temperature in degrees Celsius corresponding to a given thermal endurance time
for a given failure criterion (typically 50 % reduction in property), derived from the Arrhenius relation of endurance time and
temperature, determined by heat aging at several elevated temperatures. Several CUT values can exist, one for each property,
endurance time and endurance criterion.
3.2.1.1 Discussion—
In practice, the continuous use temperature for a plastic, involves other environmental considerations as discussed elsewhere in this
standard, than thermal endurance alone. The term, CUT, used here, is intended as an index for thermal endurance alone. The use
of this term is found in automotive applications of plastics. The endurance time used for the CUT value reported should be
specified as CUT (endurance time).
3.2.2 temperature index (TI), also referred to as thermal index (TI)—the temperature in degrees Celsius corresponding to an
endurance time of 20,000 hours for a given failure criterion (typically 50% reduction in property), derived from the Arrhenius
relation of endurance time and temperature, usually determined by heat aging at several elevated temperatures.
3.2.2.1 Discussion—
The TI can thus be seen as a special case of CUT where the endurance time is fixed at 20,000 hours. A given plastic material and
property and its retention criterion may be characterized by several CUT times, for example, CUT (1000 hours), CUT (5000 hours),
etc. as needed per requirements of different applications. Further, several TI values can exist, one for each property and endurance
criterion.
4. Significance and Use
4.1 The use of this practice presupposes that the failure criteria selected to evaluate materials (that is, the property or properties
being measured as a function of exposure time) and the duration of the exposure can be shown to relate to the intended use of the
materials.
4.2 Plastic materials exposed to heat may be are subject to many types of physical and chemical changes. The severity of the
exposures in both time and temperature determines the extent and type of change that takes place. A plastic material is not
necessarily degraded by exposure to elevated temperatures, but may be unchanged or improved. temperatures. However, extended
periods of exposure of plastics to elevated temperatures will generally cause some degradation, with progressive changechanges
in physical properties. Specific properties and failure (or lifetime) criteria for these properties are typically chosen for the
evaluation of thermal endurance.
4.3 Generally, short exposures at elevated temperatures may drive out volatiles such as moisture, solvents, or plasticizers,
relieve molding stresses, advance the cure of thermosets, and may cause some change in color of the plastic or coloring agent, or
both. Normally, additional shrinkage should be expected with loss of volatiles or advance in polymerization.
4.4 Some plastic materials may become brittle due to loss of plasticizers after exposure at elevated temperatures. Other types
of plastics may become soft and sticky, either due to sorption of volatilized plasticizer or due to breakdown of the polymer.
4.5 The degree of change observed will depend on the property measured. Different properties, mechanical or electrical, may
not change at the same rate. For instance, the arc resistance of thermosetting compounds improves up to the carbonization point
of the material. Mechanical properties, such as flexural properties, are sensitive to heat degradation and may change at a more rapid
rate. Ultimate properties such as strength or elongation are more sensitive to degradation than bulk properties such as modulus,
in most cases.
4.6 The material studied can change inherent behavior with change in temperature as for example when crossing α, β, and γ
transitions. These transitions should be avoided both in the range of aging temperatures used, as well as in extrapolation of the
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D3045 − 18
lifeline. Arrhenius principles may only be used to accelerate a chemical mechanism if there are no fundamental changes in the
material properties. With semi-crystalline and highly crystalline polymers, elevated temperatures may cause significant changes to
the morphology of the material, invalidating or compromising that assumption.
NOTE 2—Caution should be exercised in using the Arrhenius relation and knowledge of physical changes in the material at elevated temperatures is
important. Guidance given in ISO 9080 for characterizing lifetime of plastic materials in pipe form by extrapolation suggests that the highest oven aging
temperature should be at least 15°C lower than the Vicat softening temperature for glassy amorphous polymers, and at least 15°C lower than the melting
point for semi-crystalline polymers.
4.7 Effects of exposure maycan be quite variable, especially when specimens are exposed for long intervals of time. Factors that
affect the reproducibility of data are the degree of temperature control of the enclosure, humidity of the oven, air velocity over the
specimen, and period of exposure. Errors in exposure are cumulative with time. Certain materials are susceptible to degradation
due to the influence of humidity in long-term heat resistance tests. Materials susceptible to hydrolysis may undergo degradation
when subjected to long-term heat resistance tests.humidity.
4.8 It is not to be inferred that comparative material ranking is undesirable or unworkable. On the contrary, this practice is
designed to provide data which can be used for such comparative purposes. However, the data obtained from this practice, since
it does not account for the influence of stress or environment that is involved in most real life applications, must be used cautiously
by the designer, who must inevitably make material choices using additional data such as creep and creep rupture that are consistent
with the requirements of histhe specific application.
4.9 It is possible for many temperature indexes to exist, in fact, one for each failure criterion. CUT and TI values to exist.
Therefore, for any application of the temperature index CUT or the TI (temperature index) to be valid, either the thermal aging
program must duplicate the intended thermal exposure conditions of the end product. If the material is stressed in the end product
in a manner not evaluated in the aging program, the temperature index thus derived is not applicable to the use of the material in
that product.product, or the Arrhenius relation must apply.
4.10 There can be very large errors when Arrhenius plots or equations based on data from experiments at a series of
temperatures are used to estimate time to produce a defined property change at some lower temperature. This estimate of time to
produce the property change or “failure” at the lower temperature is often called the “service life.” life;” however, using this term
should be avoided as this implies the tester has information on specific failure criteria in end-use, while numerous factors are not
under the scope of this test. It is preferable to use terms such as “end point,” “thermal endurance time,” and such. Because of the
errors associated with these calculations, this endurance time should be considered as “maximum expected” rather than “typical.”
5. Apparatus
5.1 Provisions for conditioning at specified standard conditions.
5.2 Oven—A controlled horizontal or vertical air flow oven, employing forced-draft circulation with substantial constant fresh
air intake is recommended. When it is necessary to avoid contamination among specimens or materials, a tubular oven method such
To harmonize with ISO 2578 and IEC standards, it is preferable to use ovens that comply with the set temperature, temperature
variation and air change requirements of Specification D5423 as Practiceevaluated D1870 may be desirable. Oven apparatus
shallby the test methods of Test Methods D5374be in accordance. Alternatively, Specification E145with Specifications may be
used, with Specification E145, Type IIB ovens for temperature aging temperatures up to 70°C. For higher70°C, and Specification
E145temperature,, Type IIA is required. Provision should be made for suspending specimens without touching each other or the
side of the chamber. Recording instrumentation to monitor the temperature of exposure is recommended.ovens for higher
...