ASTM D7474-12
(Practice)Standard Practice for Determining Residual Stresses in Extruded or Molded Sulfone Plastic (SP) Parts by Immersion in Various Chemical Reagents
Standard Practice for Determining Residual Stresses in Extruded or Molded Sulfone Plastic (SP) Parts by Immersion in Various Chemical Reagents
SIGNIFICANCE AND USE
Thermoplastic moldings contain residual stresses due to differential cooling rates through the thickness of the molding. Changes in residual stress have been found to occur with time after molding due to stress relaxation. Many part performance parameters as well as part failures are affected by the level of residual stress present in a part. Residual stresses cause shrinkage, warpage, and a decrease in environmental stress crack resistance. This practice estimates the relative magnitude of residual stresses in parts produced from the series of sulfone plastics (SP), namely polysulfone (PSU), polyethersulfone (PESU), and polyphenylsulfone (PPSU) materials.
No direct correlation has been established between the results of the determination of residual stresses by this practice and part performance properties. For this reason, this practice is not recommended as a substitute for other tests, nor is it intended for use in purchasing specifications for parts. Despite this limitation, this practice does yield information of value in indicating the presence of residual stresses and the relative quality of plastic parts.
Residual stresses cannot be easily calculated, hence it is important to have an experimental method, such as this practice, to estimate residual stresses.
This practice is useful for extruders and molders who wish to evaluate residual stresses in SP parts. This can be accomplished by visual examination after immersion in one or more chemical reagents to evaluate whether or not cracking occurs. Stresses will relax after molding or extrusion. Accordingly, both immersion in the test medium and visual examination must be made at identical times and conditions after processing, if comparing parts. It is important to note the differences in part history. Thus, this technique may be used as an indication for quality of plastic processing.
The practice is useful primarily for indicating residual stresses near the surface.
SCOPE
1.1 This practice covers the evaluation of residual stresses in extruded profile or molded SP parts. The presence and relative magnitude of residual stresses are indicated by the crazing of the specimen part upon immersion in one or more of a series of chemical reagents. The specified chemical reagents were previously calibrated by use of Environmental Stress Cracking (ESC) techniques to cause crazing in sulfone plastics (SP) at specified stress levels.
1.2 This practice applies only to unfilled injection molding and extrusion grade materials of high molecular weight as indicated by the following melt flow rates: PSU 9 g/10 min, max., PESU 30 g/10 m, max, and PPSU 25 g/10 min, max. Lower molecular weight (higher melt flow) materials will craze at lower stress levels than indicated in Tables 1-3. (See Specification D6394 for melt flow rate conditions.)
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
Note 1—There is no known ISO equivalent for this standard.
1.4 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.
TABLE 1 Liquid Reagents for Residual Stress Test for PSU MixtureMixture CompositionCritical Stress, MPa (psi) % by volume Ethanol% by volume Ethyl Acetate 1505015.2 (2200) 2435712.1 (1750) 337639.0 (1300) 425755.5 (800)
TABLE 2 Liquid Reagents for Residual Stress Test for PESU MixtureMixture CompositionCritical Stress, MPa (psi) % by volume Ethanol% by volume MEK 1505017.9 (2600) 2406010.3 (1500) 320806.9 (1000) 401005.9 (850)
TABLE 3 Liquid Reagents for Residual Stress Test for PPSU MixtureMixture CompositionCritical Stress, MPa (psi) % by volume Ethanol% by volume MEK 1505022.8 (3300) 2257513.8 (2000) 310909.0 (1300) 401008.0 (1150)
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Designation: D7474 − 12
Standard Practice for
Determining Residual Stresses in Extruded or Molded
Sulfone Plastic (SP) Parts by Immersion in Various
1
Chemical Reagents
This standard is issued under the fixed designation D7474; 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* D4000 Classification System for Specifying Plastic Materi-
als
1.1 This practice covers the evaluation of residual stresses
D6394 Specification for Sulfone Plastics (SP)
in extruded profile or molded SP parts. The presence and
3
2.2 ISO Standard:
relative magnitude of residual stresses are indicated by the
ISO 22088–3 Plastics—Determination of Resistance to En-
crazing of the specimen part upon immersion in one or more of
vironmental Stress Cracking (ESC)—Part 3: Bent Strip
a series of chemical reagents. The specified chemical reagents
Method
were previously calibrated by use of Environmental Stress
Cracking (ESC) techniques to cause crazing in sulfone plastics
3. Terminology
(SP) at specified stress levels.
3.1 Definitions—For definitions of technical terms pertain-
1.2 This practice applies only to unfilled injection molding
ing to plastics used in this practice, see Terminology D883.
and extrusion grade materials of high molecular weight as
indicated by the following melt flow rates: PSU 9 g/10 min,
4. Summary of Practice
max., PESU 30 g/10 m, max, and PPSU 25 g/10 min, max.
4.1 The practice involves the exposure of finished plastic
Lowermolecularweight(highermeltflow)materialswillcraze
parts to a specified series of chemical reagents which are
at lower stress levels than indicated in Tables 1-3. (See
known to produce cracking or crazing of Sulfone Plastic (SP)
Specification D6394 for melt flow rate conditions.)
materials at specific stress levels, under otherwise constant
1.3 The values stated in SI units are to be regarded as the
conditions including a fixed time of one minute. Thus, the
standard. The values given in parentheses are for information
exposure of finished parts to one or more chemical reagents
only.
under no load conditions allows the quantification of the
NOTE 1—There is no known ISO equivalent for this standard.
residual stress levels in the finished parts. Since the evaluation
1.4 This standard does not purport to address all of the
is based on the subjective criteria of presence or absence of
safety concerns, if any, associated with its use. It is the
crazing, this practice only yields an approximate indication of
responsibility of the user of this standard to establish appro-
the level of residual stresses in the parts. This practice
priate safety and health practices and determine the applica-
estimates the relative magnitude of residual stresses in parts
bility of regulatory limitations prior to use.
produced from the series of sulfone plastics, namely polysul-
fone (PSU), polyethersulfone (PESU), and polyphenylsulfone
2. Referenced Documents
(PPSU) materials.
2
2.1 ASTM Standards:
5. Significance and Use
D543 Practices for Evaluating the Resistance of Plastics to
5.1 Thermoplastic moldings contain residual stresses due to
Chemical Reagents
differential cooling rates through the thickness of the molding.
D883 Terminology Relating to Plastics
Changes in residual stress have been found to occur with time
after molding due to stress relaxation. Many part performance
1
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand parameters as well as part failures are affected by the level of
is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.
residual stress present in a part. Residual stresses cause
Current edition approved April 1, 2012. Published May 2012. Originally
shrinkage, warpage, and a decrease in environmental stress
approved in 2008. Last previous edition approved in 2008 as D7474 - 08.
crack resistance.This practice estimates the relative magnitude
DOI:10.1520/D7474-12.
2
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
3
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 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
1
---------------------- Page: 1 ----------------------
D7474 − 12
TABLE 1 Liquid Reagents for Residual Stress Test for PSU
Mixture Composition
Mixture
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:D7474–08 Designation:D7474–12
Standard Practice for
Determining Residual Stresses in Extruded or Molded
Sulfone Plastic (SP) Parts by Immersion in Various
1
Chemical Reagents
This standard is issued under the fixed designation D7474; 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 the evaluation of residual stresses in extruded profile or molded SP parts. The presence and relative
magnitude of residual stresses are indicated by the crazing of the specimen part upon immersion in one or more of a series of
chemical reagents. The specified chemical reagents were previously calibrated by use of Environmental Stress Cracking (ESC)
techniques to cause crazing in sulfone plastics (SP) at specified stress levels.
1.2 This practice applies only to unfilled injection molding and extrusion grade materials of high molecular weight as indicated
by the following melt flow rates: PSU 9 g/10 min, max., PESU 30 g/10 m, max, and PPSU 25 g/10 min, max. Lower molecular
weight (higher melt flow) materials will craze at lower stress levels than indicated inTables 1-3. (See Specification D6394 for melt
flow rate conditions.)
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
NOTE1—There is no equivalent ISO standard. 1—There is no known ISO equivalent for this standard.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D543 Practices for Evaluating the Resistance of Plastics to Chemical Reagents
D883 Terminology Relating to Plastics
D4000 Classification System for Specifying Plastic Materials
D6394 Specification for Sulfone Plastics (SP)
3
2.2 ISO Standard:
ISO 22088–3 Plastics—Determination of Resistance to Environmental Stress Cracking (ESC)—Part 3: Bent Strip Method
3. Terminology
3.1 Definitions—For definitions of technical terms pertaining to plastics used in this practice, see Terminology D883.
4. Summary of Practice
4.1 The practice involves the exposure of finished plastic parts to a specified series of chemical reagents which are known to
produce cracking or crazing of Sulfone Plastic (SP) materials at specific stress levels, under otherwise constant conditions
including a fixed time of one minute. Thus, the exposure of finished parts to one or more chemical reagents under no load
conditionsallowsthequantificationoftheresidualstresslevelsinthefinishedparts.Sincetheevaluationisbasedonthesubjective
criteria of presence or absence of crazing, this practice only yields an approximate indication of the level of residual stresses in
the parts. This practice estimates the relative magnitude of residual stresses in parts produced from the series of sulfone plastics,
namely polysulfone (PSU), polyethersulfone (PESU), and polyphenylsulfone (PPSU) materials.
1
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.
Current edition approved Aug. 1, 2008. Published September 2008. DOI: 10.1520/D7474-08.
CurrenteditionapprovedApril1,2012.PublishedMay2012.Originallyapprovedin2008.Lastpreviouseditionapprovedin2008asD7474 - 08.DOI:10.1520/D7474-12.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 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.
1
---------------------- Page: 1 ----------------------
D7474–12
TABLE 1 Liquid Reagents for Residual Stress Test for PSU
Mixture Composition
Mixture Critical Stress, MPa (psi)
% by volume Ethanol %byvolumeMEK
% by volume Ethanol % by volume Ethyl Acetate
1 50 50 15.2 (2200)
2 43 57
...
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