ASTM D5870-22

Standard Practice for Calculating Property Retention Index of Plastics

SIGNIFICANCE AND USE
4.1 The property retention index (PRI) determined by this practice is intended primarily to provide relative durability performance information on materials for design engineers. It is up to the user to ensure that appropriate sampling procedures are used for the selection of specimens to be exposed so that the PRI data obtained is actually representative of the material being evaluated.  
4.2 The PRI obtained depends on the material being tested, property being evaluated, and exposure condition used. A PRI obtained for one property will probably not be the same as the PRI for a different property of the same material, even if the same exposure test is used.  
4.3 Plastics exposed to a combination of environmental and thermal treatments may undergo a change in functional performance. Any laboratory-accelerated aging procedure, especially those that use only a single stress, may not realistically indicate the changes a plastic may undergo in actual use conditions. This practice provides a means for expressing the changes in properties as a function of time exposed in a wide variety of tests. The PRI data obtained is best used for comparing the performance of materials subjected to the same exposure test simultaneously.  
4.3.1 Both laboratory-accelerated and outdoor exposure testing can be highly variable, and the PRI data will be influenced by this variability. For example, PRI data from outdoor exposures can vary depending on the exposure location and the time of year when the exposure is conducted. Variability in laboratory-accelerated exposure tests can result in large differences in PRI data from two laboratories running supposedly identical tests. PRI data obtained from exposure to laboratory-accelerated tests cannot be used to predict the PRI for exposure to natural weathering or actual use conditions unless there is a sufficient amount of data from both types of exposure to allow valid statistical comparisons.  
4.4 A number of different exposure techniqu...
SCOPE
1.1 This practice covers procedures for the calculation of a property retention index (PRI) of thermoplastic and thermoset plastics after exposure to thermal aging, natural or artificial accelerated weathering, or chemical exposures.  
1.2 This practice is not intended to establish a fixed procedure for conducting the exposure test, but it is intended to provide a set of specific procedures used to calculate the retention index of a characteristic property of the material after it has been exposed. Selection of the specific exposure test conditions depends on the material being tested and the property being measured. It is up to the user to determine which exposure test conditions are most relevant to the specific material and the service condition being used. The exposure test used must be conducted in accordance with conditions described in specific exposure standards.  
1.3 This practice does not describe procedures for sampling the materials to be tested. These procedures are described in the standards and specifications applicable to the material being evaluated.  
1.4 The procedure used to calculate the PRI depends on whether the test used to characterize the materials being exposed is destructive or nondestructive. The PRI can be useful in describing short-term mechanical, electrical, and other properties of plastics at specified temperatures after the materials have been subjected to an exposure test.  
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: There is no similar or equivalent ISO standard. ISO 11248 is significantly different since it pertains only to thermosetting resins.  
1.6 This international standard was developed in accordance with in...

General Information

• Status: Published
• Publication Date: 30-Jun-2022
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.50 - Durability of Plastics

Relations

• 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 D2565-23 - Standard Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
• Effective Date: 01-Oct-2023
• Refers: ASTM D1898-68(1989) - Standard Practice for Sampling of Plastics (Withdrawn 1998)
• Effective Date: 29-Sep-2023
• 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 D4674-19 - Standard Practice for Accelerated Testing for Color Stability of Plastics Exposed to Indoor Office Environments
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-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 D3045-18 - Standard Practice for Heat Aging of Plastics Without Load
• Effective Date: 01-Aug-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM G113-14 - Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
• Effective Date: 01-Mar-2014
• Refers: ASTM D883-12e1 - Standard Terminology Relating to Plastics
• Effective Date: 15-Nov-2012

Overview

ASTM D5870-22: Standard Practice for Calculating Property Retention Index of Plastics provides industry guidance for calculating the property retention index (PRI) of both thermoplastic and thermoset plastics. PRI is an essential comparative metric used by design engineers and material scientists to assess the relative durability and performance of plastics after exposure to various aging factors, such as heat, natural and artificial weathering, and chemical environments. This standard offers procedures for calculating the PRI following different exposure conditions, but does not specify fixed test methods for performing the exposure itself.

Key Topics

• Property Retention Index (PRI): Measures the retention of a specific material property after exposure to defined conditions. The PRI offers a relative comparison of durability and is calculated for individual properties, which may vary depending on the property and the exposure method.
• Exposure Conditions: PRI can be determined after plastic materials are subjected to:
  • Thermal aging
  • Natural outdoor weathering
  • Artificial accelerated weathering (using UV, xenon-arc, carbon-arc, or fluorescent lamps)
  • Chemical exposures
• Testing Methods: The approach depends on whether the property measurement is destructive or nondestructive in nature. All procedures require clear identification of the material, test conditions, and result calculations.
• Reporting Requirements: To ensure meaningful and reproducible results, the standard specifies detailed reporting of specimen preparation, environmental conditions, methods of property measurement, and exposure details.
• Variability and Limitations: Laboratory-accelerated and outdoor tests can show substantial variability depending on location, equipment, and season, making direct comparison of PRI between different exposure types unreliable without sufficient parallel data.

Applications

ASTM D5870-22 finds practical application in several areas, including:

• Material Selection for Design: Design engineers use PRI data to compare the relative long-term performance or durability of plastics when selecting materials for new products.
• Comparative Performance Testing: Manufacturers and quality control labs employ PRI calculations to rank plastics according to their resistance to environmental and thermal stresses using standardized or custom exposure procedures.
• Product Development: Researchers utilize PRI as a tool to gauge the effectiveness of additives, stabilizers, or formulation changes intended to enhance the performance of plastic materials.
• Regulatory Documentation: PRI results generated under this standard can support regulatory filings, certifications, and warranty substantiation by providing an objective measure of property retention.
• Benchmarking: PRI is valuable for benchmarking the weatherability, heat stability, and chemical resistance of plastics across different formulations, suppliers, and production lots.

Related Standards

The calculation of PRI under ASTM D5870-22 often references or is used in conjunction with the following related standards:

• ASTM D543 - Practices for Evaluating the Resistance of Plastics to Chemical Reagents
• ASTM D1435 - Practice for Outdoor Weathering of Plastics
• ASTM D2565 - Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
• ASTM D3045 - Practice for Heat Aging of Plastics Without Load
• ASTM D4329 - Practice for Fluorescent UV Exposure of Plastics
• ASTM D4459 - Practice for Xenon-Arc Exposure of Plastics for Indoor Applications
• UL 746B - Polymeric Materials-Long Term Property Evaluations
• ISO 291 - Plastics-Standard Atmospheres for Conditioning and Testing
• ISO 4892 - Plastics-Methods of Exposure to Laboratory Light Sources

Note: There is no directly equivalent ISO standard for PRI; ISO 11248 is related but limited to thermosetting resins only.

Applying ASTM D5870-22 ensures clear, consistent, and industry-accepted methods for calculating property retention index, enabling more reliable design, quality assurance, and validation of plastic materials in real-world applications. Using this practice helps stakeholders minimize risk, optimize material selection, and improve confidence in performance claims related to plastic durability.

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: D5870 − 22
Standard Practice for
Calculating Property Retention Index of Plastics
This standard is issued under the fixed designation D5870; 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* Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This practice covers procedures for the calculation of a
Barriers to Trade (TBT) Committee.
property retention index (PRI) of thermoplastic and thermoset
plastics after exposure to thermal aging, natural or artificial
2. Referenced Documents
accelerated weathering, or chemical exposures.
2.1 ASTM Standards:
1.2 This practice is not intended to establish a fixed proce-
D543 Practices for Evaluating the Resistance of Plastics to
dure for conducting the exposure test, but it is intended to
Chemical Reagents
provide a set of specific procedures used to calculate the
D618 Practice for Conditioning Plastics for Testing
retention index of a characteristic property of the material after
D883 Terminology Relating to Plastics
it has been exposed. Selection of the specific exposure test
D1435 Practice for Outdoor Weathering of Plastics
conditions depends on the material being tested and the
D1499 Practice for Filtered Open-Flame Carbon-Arc Expo-
property being measured. It is up to the user to determine
sures of Plastics
whichexposuretestconditionsaremostrelevanttothespecific 3
D1898 Practice for Sampling of Plastics (Withdrawn 1998)
material and the service condition being used. The exposure
D2565 Practice for Xenon-Arc Exposure of Plastics In-
test used must be conducted in accordance with conditions
tended for Outdoor Applications
described in specific exposure standards.
D3045 Practice for Heat Aging of Plastics Without Load
1.3 This practice does not describe procedures for sampling
D4329 Practice for Fluorescent Ultraviolet (UV) Lamp Ap-
thematerialstobetested.Theseproceduresaredescribedinthe
paratus Exposure of Plastics
standards and specifications applicable to the material being
D4364 Practice for Performing OutdoorAccelerated Weath-
evaluated.
ering Tests of Plastics Using Concentrated Sunlight
D4459 Practice for Xenon-Arc Exposure of Plastics In-
1.4 The procedure used to calculate the PRI depends on
tended for Indoor Applications
whether the test used to characterize the materials being
D4674 PracticeforAcceleratedTestingforColorStabilityof
exposedisdestructiveornondestructive.ThePRIcanbeuseful
Plastics Exposed to Indoor Office Environments
in describing short-term mechanical, electrical, and other
D6360 Practice for Enclosed Carbon-Arc Exposures of Plas-
properties of plastics at specified temperatures after the mate-
tics
rials have been subjected to an exposure test.
G113 Terminology Relating to Natural andArtificial Weath-
1.5 This standard does not purport to address all of the
ering Tests of Nonmetallic Materials
safety concerns, if any, associated with its use. It is the
2.2 ISO Standards:
responsibility of the user of this standard to establish appro-
ISO 291 Plastics—Standard Atmospheres for Conditioning
priate safety, health, and environmental practices and deter-
and Testing
mine the applicability of regulatory limitations prior to use.
ISO 877 Plastics—Methods of Exposure to Solar Radiation,
NOTE 1—There is no similar or equivalent ISO standard. ISO 11248 is
Part 1: General Guidance, Part 2: Direct Weathering and
significantly different since it pertains only to thermosetting resins.
Exposure Behind Window Glass, and Part 3: Intensified
1.6 This international standard was developed in accor-
Weathering Using Concentrated Solar Radiation
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
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
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand the ASTM website.
is the direct responsibility of Subcommittee D20.50 on Durability of Plastics. The last approved version of this historical standard is referenced on
Current edition approved July 1, 2022. Published July 2022. Originally approved www.astm.org.
in 1995. Last previous edition approved in 2016 as D5870 - 16. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
D5870-22. 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
D5870 − 22
ISO 4892 Plastics—Methods of Exposure to Laboratory D4674; and ISO 877 and ISO 4892). When it is desirable to
Light Sources Part 1: General Guidance, Part 2: Xenon evaluate the effects of heat alone, exposures should be con-
Arc Lamps, Part 3: Fluorescent UV Lamps, and Part 4: ductedinaccordancewithPracticeD3045.Whenitisdesirable
Open Flame Carbon Arc Exposures to evaluate the effects of chemical exposures, the exposures
ISO 11248 Plastics—Thermosetting Molding Materials, should be conducted in accordance with Test Method D543.
Evaluation of Short-Term Performance at Elevated Tem-
4.5 There are a number of factors influencing the physical
peratures
properties and the retention of these properties after exposure.
2.3 Underwriters Laboratories Standards:
In addition to a complete description of the exposure test
UL 746B Polymeric Materials—Long Term Property Evalu-
conditions used, the following information shall be included in
ations
anyreportreferencingthispractice:(1)completedescriptionof
the material tested, including the type, source, manufacturer’s
3. Terminology
code number, form, and previous history; (2) methods of
3.1 Definitions: The terminology given in Terminologies
preparation for the material and individual test specimens; (3)
D883 and G113 is applicable to this practice.
procedure used for specimen conditioning prior to and after
exposure; (4) complete description of the environment in
4. Significance and Use
which the physical properties were determined (for example,
4.1 The property retention index (PRI) determined by this temperatureandrelativehumidity);(5)completedescriptionof
practice is intended primarily to provide relative durability the procedure used to determine the physical properties tested,
performance information on materials for design engineers. It including the rate at which specimens were tested, if appli-
isuptotheusertoensurethatappropriatesamplingprocedures cable; (6) if applicable, void content of the specimens tested
are used for the selection of specimens to be exposed so that and the method used to measure void content.
the PRI data obtained is actually representative of the material
NOTE 2—It is not the intent of this practice to require users to divulge
being evaluated.
proprietary information regarding composition. To avoid divulging pro-
prietary information, generic descriptions may be used to provide infor-
4.2 The PRI obtained depends on the material being tested,
mation on material composition.
property being evaluated, and exposure condition used. A PRI
4.6 When destructive tests are used to determine a physical
obtained for one property will probably not be the same as the
or chemical change, or both, which occurs as a result of
PRI for a different property of the same material, even if the
exposure, the amount of change is expressed as a function of
same exposure test is used.
the value obtained for the material tested at a specified test
4.3 Plastics exposed to a combination of environmental and
environment (for example, temperature and humidity). The
thermal treatments may undergo a change in functional perfor-
exposed and reference specimens are measured at the same
mance.Any laboratory-accelerated aging procedure, especially
time in the specified test environment.
thosethatuseonlyasinglestress,maynotrealisticallyindicate
4.7 When nondestructive tests are used to determine a
the changes a plastic may undergo in actual use conditions.
physical or chemical change, or both, which occurs as a result
This practice provides a means for expressing the changes in
ofexposure,theamountofchangeisexpressedasafunctionof
properties as a function of time exposed in a wide variety of
the value obtained on the specimens prior to exposure. Prop-
tests. The PRI data obtained is best used for comparing the
erty measurement tests on the specimens before and after
performance of materials subjected to the same exposure test
exposure shall be conducted at the same conditions (for
simultaneously.
example, temperature and humidity).
4.3.1 Both laboratory-accelerated and outdoor exposure
testing can be highly variable, and the PRI data will be
4.8 The property or properties to be measured may be
influenced by this variability. For example, PRI data from
specified in an ASTM, ISO, or other appropriate standard for
outdoor exposures can vary depending on the exposure loca-
the material being tested, or by any prior agreement between
tion and the time of year when the exposure is conducted.
interested parties. If the method used to measure the property
Variability in laboratory-accelerated exposure tests can result
being evaluated is not described in an ASTM, ISO, or other
in large differences in PRI data from two laboratories running
appropriate standard, a description of the test method shall be
supposedly identical tests. PRI data obtained from exposure to
included in the report of test results.
laboratory-accelerated tests cannot be used to predict the PRI
4.9 It is realized that a material cannot be tested without
for exposure to natural weathering or actual use conditions
specifying the method of preparation. To have any meaning in
unless there is a sufficient amount of data from both types of
comparative testing, specimens of each material being evalu-
exposure to allow valid statistical comparisons.
ated by these test procedures should be prepared or molded
4.4 A number of different exposure techniques can be used
from the same lot under identical processing conditions and
to provide information on the effects of environmental stresses
randomizedpriortotestingattheconditionsdesired.Itmustbe
such as light, heat, and water on plastics (see Practices D1435,
realized that lot-to-lot variation in the material may cause
D1499, D2565, D4329, D4364, and D4459; Test Method
additional variability in results.
NOTE 3—For those plastics with a Tg greater than ambient, the slow
Available from Underwriters Laboratories (UL), UL Headquarters, 333 Pfing- collapse of free volume, with attendant significant changes in mechanical
sten Road, Northbrook, IL, 60062, http://www.ul.com. properties such as fatigue resistance, impact resistance, yield stress, and
D5870 − 22
vaportransmission,etc.willbeacceleratedatelevatedtemperaturesbelow
sured.Largenumbersoftestspecimensshouldbeusedincases
the Tg but will be reversed at temperatures above the Tg. Therefore,
of extreme variability, in which the standard deviation of test
incubation of material at elevated temperatures in the Tg range may be
results is more than 20 % of the mean value. If the test method
erratically susceptible to oven fluctuation effects.
used does not require a specific number of test specimens, a
4.10 The results depend on which side of the test specimen
minimum of five replicate specimens of each material shall be
is exposed with some tests. In bending tests, for example,
used.
different results are obtained in accordance with whether the
NOTE 4—It may be advisable to double the number of specimens to
exposed surface or the unexposed surface of the test specimen
twice that recommended by a test method, for example, use ten tensile
is placed under tension. Care must be taken to ensure that all
specimens instead of five, to get a more reliable estimate of property
specimens being exposed have the same orientation in the test
retention, and in particular for the control. This is a practice used for the
fixtureusedtoholdthespecimensduringexposure.Inaddition,
baseline material for heat aging studies in UL 746B, since the baseline
value is used for many property retention estimates from tests after
the results also depend on the orientation of test specimens
different exposures.
during the procedure used to measure the property being
monitored.This is especially true with impact tests. During the
8. Procedure
procedure used to measure the characteristic property, care
8.1 Exposure of Test Specimens
must be taken to ensure that all specimens are oriented the
8.1.1 When determining the PRI for materials exposed to
same way in the test fixture.
natural weathering, conduct exposures in accordance with
4.11 Before proceeding with this practice, reference should
Practice D1435.
be made to the specification of the material being tested. Any
8.1.2 When the PRI for exposure to concentrated natural
test specimen preparation, con
...

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: D5870 − 16 D5870 − 22
Standard Practice for
Calculating Property Retention Index of Plastics
This standard is issued under the fixed designation D5870; 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 This practice covers procedures for the calculation of a property retention index (PRI) of thermoplastic and thermoset plastics
after exposure to thermal aging, natural or artificial accelerated weathering, or chemical exposures.
1.2 This practice is not intended to establish a fixed procedure for conducting the exposure test, but it is intended to provide a set
of specific procedures used to calculate the retention index of a characteristic property of the material after it has been exposed.
Selection of the specific exposure test conditions depends on the material being tested and the property being measured. It is up
to the user to determine which exposure test conditions are most relevant to the specific material and the service condition being
used. The exposure test used must be conducted in accordance with conditions described in specific exposure standards.
1.3 This practice does not describe procedures for sampling the materials to be tested. These procedures are described in the
standards and specifications applicable to the material being evaluated.
1.4 The procedure used to calculate the PRI depends on whether the test used to characterize the materials being exposed is
destructive or nondestructive. The PRI can be useful in describing short-term mechanical, electrical, and other properties of plastics
at specified temperatures after the materials have been subjected to an exposure test.
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—There is no similar or equivalent ISO standard. ISO 11248 is significantly different since it pertains only to thermosetting resins.
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:
D543 Practices for Evaluating the Resistance of Plastics to Chemical Reagents
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1435 Practice for Outdoor Weathering of Plastics
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 April 1, 2016July 1, 2022. Published April 2016July 2022. Originally approved in 1995. Last previous edition approved in 20112016 as
D5870 - 11.D5870 - 16. DOI: 10.1520/D5870-16.10.1520/D5870-22.
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
D5870 − 22
D1499 Practice for Filtered Open-Flame Carbon-Arc Exposures of Plastics
D1898 Practice for Sampling of Plastics (Withdrawn 1998)
D2565 Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
D3045 Practice for Heat Aging of Plastics Without Load
D4329 Practice for Fluorescent Ultraviolet (UV) Lamp Apparatus Exposure of Plastics
D4364 Practice for Performing Outdoor Accelerated Weathering Tests of Plastics Using Concentrated Sunlight
D4459 Practice for Xenon-Arc Exposure of Plastics Intended for Indoor Applications
D4674 Practice for Accelerated Testing for Color Stability of Plastics Exposed to Indoor Office Environments
D6360 Practice for Enclosed Carbon-Arc Exposures of Plastics
G113 Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
2.2 ISO Standards:
ISO 291 Plastics—Standard Atmospheres for Conditioning and Testing
ISO 877 Plastics—Methods of Exposure to Solar Radiation, Part 1: General Guidance, Part 2: Direct Weathering and Exposure
Behind Window Glass, and Part 3: Intensified Weathering Using Concentrated Solar Radiation
ISO 4892 Plastics—Methods of Exposure to Laboratory Light Sources Part 1: General Guidance, Part 2: Xenon Arc Lamps, Part
3: Fluorescent UV Lamps, and Part 4: Open Flame Carbon Arc Exposures
ISO 11248 Plastics—Thermosetting Molding Materials, Evaluation of Short-Term Performance at Elevated Temperatures
2.3 Underwriters Laboratories Standards:
UL 746B Polymeric Materials—Long Term Property Evaluations
3. Terminology
3.1 Definitions: The terminology given in Terminologies D883 and G113 is applicable to this practice.
4. Significance and Use
4.1 The property retention index (PRI) determined by this practice is intended primarily to provide relative durability performance
information on materials for design engineers. It is up to the user to ensure that appropriate sampling procedures are used for the
selection of specimens to be exposed so that the PRI data obtained is actually representative of the material being evaluated.
4.2 The PRI obtained depends on the material being tested, property being evaluated, and exposure condition used. A PRI obtained
for one property will probably not be the same as the PRI for a different property of the same material, even if the same exposure
test is used.
4.3 Plastics exposed to a combination of environmental and thermal treatments may undergo a change in functional performance.
Any laboratory-accelerated aging procedure, especially those that use only a single stress, may not realistically indicate the changes
a plastic may undergo in actual use conditions. This practice provides a means for expressing the changes in properties as a function
of time exposed in a wide variety of tests. The PRI data obtained is best used for comparing the performance of materials subjected
to the same exposure test simultaneously.
4.3.1 Both laboratory-accelerated and outdoor exposure testing can be highly variable, and the PRI data will be influenced by this
variability. For example, PRI data from outdoor exposures can vary depending on the exposure location and the time of year when
the exposure is conducted. Variability in laboratory-accelerated exposure tests can result in large differences in PRI data from two
laboratories running supposedly identical tests. PRI data obtained from exposure to laboratory-accelerated tests cannot be used to
predict the PRI for exposure to natural weathering or actual use conditions unless there is a sufficient amount of data from both
types of exposure to allow valid statistical comparisons.
4.4 A number of different exposure techniques can be used to provide information on the effects of environmental stresses such
as light, heat, and water on plastics (see Practices D1435, D1499, D2565, D4329, D4364, and D4459; Test Method D4674; and
ISO 877 and ISO 4892). When it is desirable to evaluate the effects of heat alone, exposures should be conducted in accordance
with Practice D3045. When it is desirable to evaluate the effects of chemical exposures, the exposures should be conducted in
accordance with Test Method D543.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from Underwriters Laboratories (UL), UL Headquarters, 333 Pfingsten Road, Northbrook, IL, 60062, http://www.ul.com.
D5870 − 22
4.5 There are a number of factors influencing the physical properties and the retention of these properties after exposure. In
addition to a complete description of the exposure test conditions used, the following information shall be included in any report
referencing this practice: (1) complete description of the material tested, including the type, source, manufacturer’s code number,
form, and previous history; (2) methods of preparation for the material and individual test specimens; (3) procedure used for
specimen conditioning prior to and after exposure; (4) complete description of the environment in which the physical properties
were determined (for example, temperature and relative humidity); (5) complete description of the procedure used to determine
the physical properties tested, including the rate at which specimens were tested, if applicable; (6) if applicable, void content of
the specimens tested and the method used to measure void content.
NOTE 2—It is not the intent of this practice to require users to divulge proprietary information regarding composition. To avoid divulging proprietary
information, generic descriptions may be used to provide information on material composition.
4.6 When destructive tests are used to determine a physical or chemical change, or both, which occurs as a result of exposure, the
amount of change is expressed as a function of the value obtained for the material tested at a specified test environment (for
example, temperature and humidity). The exposed and reference specimens are measured at the same time in the specified test
environment.
4.7 When nondestructive tests are used to determine a physical or chemical change, or both, which occurs as a result of exposure,
the amount of change is expressed as a function of the value obtained on the specimens prior to exposure. Property measurement
tests on the specimens before and after exposure shall be conducted at the same conditions (for example, temperature and
humidity).
4.8 The property or properties to be measured may be specified in an ASTM, ISO, or other appropriate standard for the material
being tested, or by any prior agreement between interested parties. If the method used to measure the property being evaluated is
not described in an ASTM, ISO, or other appropriate standard, a description of the test method shall be included in the report of
test results.
4.9 It is realized that a material cannot be tested without specifying the method of preparation. To have any meaning in
comparative testing, specimens of each material being evaluated by these test procedures should be prepared or molded from the
same lot under identical processing conditions and randomized prior to testing at the conditions desired. It must be realized that
lot-to-lot variation in the material may cause additional variability in results.
NOTE 3—For those plastics with a Tg greater than ambient, the slow collapse of free volume, with attendant significant changes in mechanical properties
such as fatigue resistance, impact resistance, yield stress, and vapor transmission, etc. will be accelerated at elevated temperatures below the Tg but will
be reversed at temperatures above the Tg. Therefore, incubation of material at elevated temperatures in the Tg range may be erratically susceptible to oven
fluctuation effects.
4.10 The results depend on which side of the test specimen is exposed with some tests. In bending tests, for example, different
results are obtained in accordance with whether the exposed surface or the unexposed surface of the test specimen is placed under
tension. Care must be taken to ensure that all specimens being exposed have the same orientation in the test fixture used to hold
the specimens during exposure. In addition, the results also depend on the orientation of test specimens during the procedure used
to measure the property being monitored. This is especially true with impact tests. During the procedure used to measure the
characteristic property, care must be taken to ensure that all specimens are oriented the same way in the test fixture.
4.11 Before proceeding with this practice, reference should be made to the specification of the material being tested. Any test
specimen preparation, conditioning, or dimensions, or some combination thereof, and testing parameters covered in the material’s
specification shall take precedence over those mentioned in this practice. The default conditions described in this practice apply
if there are no material specifications.
5. Apparatus
5.1 The apparatus used for exposure and measurement of the property desired will depend on the particular exposure used and
property being measured. Refer to the appropriate ASTM or ISO standards for requirements on the apparatus needed.
D5870 − 22
6. Sampling
6.1 Sampling of materials for testing is covered under applicable standards or specifications for the material being tested.
6.2 It is important to select samples for testing that are representative of the material being evaluated. Procedures for sampling
plastics are described in Practice D1898.
7. Test Specimens
7.1 The test specimens shall be in accordance with the appropriate test meth
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