ASTM F791-18

Standard Test Method for Stress Crazing of Transparent Plastics

SIGNIFICANCE AND USE
4.1 This test method provides a guide for evaluating whether a specific solvent, chemical, or compound is detrimental to a transparent plastic as a result of a manufacturing process, a fabrication operation, or the operational environment. All transparent plastics are susceptible to crazing, though in widely varying degree and from a variety of causes. This test method is intended to allow establishment of the crazing stress when the simultaneous action of both load and a material that will cause crazing is applied, producing non-reversible damage that limits the usage of that transparent plastic in a specific application.
SCOPE
1.1 This test method covers the determination of the critical crazing stress for a transparent plastic material when exposed to a specific solvent, chemical, or compound at a specific temperature.  
1.2 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.  
1.3 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.

General Information

• Status: Historical
• Publication Date: 31-May-2018
• ICS: 83.080.01 - Plastics in general
• Technical Committee: F07 - Aerospace and Aircraft
• Drafting Committee: F07.08 - Transparent Enclosures and Materials

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F791 − 18
Standard Test Method for
1
Stress Crazing of Transparent Plastics
ThisstandardisissuedunderthefixeddesignationF791;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
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 3.1.1.1 Discussion—Crazing is a form of yielding in poly-
mers characterized by a spongy void filled fibrillar structure.
1.1 This test method covers the determination of the critical
The density in the craze changes resulting in a change in the
crazing stress for a transparent plastic material when exposed
index of refraction, which causes light to be reflected off of the
to a specific solvent, chemical, or compound at a specific
crazes. This light reflection causes the crazes to sparkle when
temperature.
viewed from certain angles. The crazes are sometimes random
1.2 This standard does not purport to address all of the
and scattered with varied lengths and depths but usually are
safety concerns, if any, associated with its use. It is the
oriented perpendicular to a tensile stress. Crazing is difficult to
responsibility of the user of this standard to establish appro-
detect. It becomes more pronounced when viewed with a light
priate safety, health, and environmental practices and deter-
source that is at an oblique angle.
mine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accor-
4. Significance and Use
dance with internationally recognized principles on standard-
4.1 This test method provides a guide for evaluating
ization established in the Decision on Principles for the
whether a specific solvent, chemical, or compound is detrimen-
Development of International Standards, Guides and Recom-
tal to a transparent plastic as a result of a manufacturing
mendations issued by the World Trade Organization Technical
process, a fabrication operation, or the operational environ-
Barriers to Trade (TBT) Committee.
ment.All transparent plastics are susceptible to crazing, though
2. Referenced Documents
inwidelyvaryingdegreeandfromavarietyofcauses.Thistest
2
method is intended to allow establishment of the crazing stress
2.1 ASTM Standards:
when the simultaneous action of both load and a material that
D618 Practice for Conditioning Plastics for Testing
will cause crazing is applied, producing non-reversible damage
E691 Practice for Conducting an Interlaboratory Study to
that limits the usage of that transparent plastic in a specific
Determine the Precision of a Test Method
application.
2.2 Other Method:
ARTC (Aircraft Research and Testing Committee of the
5. Apparatus
Aircraft Industries Association of America, Inc.) Condi-
3
tioning Method
5.1 Test Fixture, with fluorescent light source illustrated and
constructed as shown in Figs. 1 and 2.
3. Terminology
5.2 Drill Fixture constructed as shown in Fig. 3.
3.1 Definitions of Terms Specific to This Standard:
3.1.1 crazing—a group of surface fissures that appear to be
5.3 Marking Fixture, constructed as shown in Fig. 3.
small cracks in the material, although they are not.
5.4 Portable Specimen Rack, constructed in the manner as
shown in Fig. 4 for handling and conditioning test specimens.
1
This test method is under the jurisdiction of ASTM Committee F07 on
5.5 Weights—A container and shot for the application of
Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on
Transparent Enclosures and Materials.
weight on the rack as shown in Fig. 1.
Current edition approved June 1, 2018. Published June 2018. Originally
approvedin1982.Lastpreviouseditionapprovedin2013asF791 – 96(2013).DOI: 5.6 Filter Paper, quantity of 0.50 by 1.0-in. (12.7 by
10.1520/F0791-18.
25.4-mm) pieces of filter, medium-retention filter paper.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6. Test Specimens
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3
6.1 The test specimen shall be machined from the transpar-
Available from Aircraft Industries Association, 1725 DeSales St. NW,
Washington, DC 20034. ent plastic material to be evaluated. A minimum of six
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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F791 − 18
FIG. 1 Accelerated Crazing Test Fixture
FIG. 3 Fixtures for Specimen Preparation
FIG. 2 Application of Test Liquid to Piece of Filter Paper on Top
Surface of Test Specimen
7. Pr
...

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: F791 − 96 (Reapproved 2013) F791 − 18
Standard Test Method for
1
Stress Crazing of Transparent Plastics
This standard is issued under the fixed designation F791; 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
1.1 This test method covers the determination of the critical crazing stress for a transparent plastic material when exposed to
a specific solvent, chemical, or compound at a specific temperature.
1.2 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.
1.3 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
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Other Method:
3
ARTC (Aircraft Research and Testing Committee of the Aircraft Industries Association of America, Inc.) Conditioning Method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 crazing—a group of surface fissures that appear to be small cracks in the material, although they are not.
3.1.1.1 Discussion—
Crazing is a form of yielding in polymers characterized by a spongy void filled fibrillar structure. The density in the craze changes
resulting in a change in the index of refraction, which causes light to be reflected off of the crazes. This light reflection causes the
crazes to sparkle when viewed from certain angles. The crazes are sometimes random and scattered with varied lengths and depths
but usually are oriented perpendicular to a tensile stress. Crazing may be is difficult to detect. It becomes more pronounced when
viewed with a light source that is at an oblique angle.
4. Significance and Use
4.1 This test method provides a guide for evaluating whether a specific solvent, chemical, or compound that may be is
detrimental to a transparent plastic as a result of a manufacturing process, a fabrication operation, or the operational environment.
All transparent plastics are susceptible to crazing, though in widely varying degree and from a variety of causes. This test method
is intended to allow establishment of the crazing stress when the simultaneous action of both load and a material that wouldwill
cause crazing is applied, producing non-reversible damage that might limit limits the usage of that transparent plastic in a specific
application.
1
This test method is under the jurisdiction of ASTM Committee F07 on Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on Transparent
Enclosures and Materials.
Current edition approved Dec. 1, 2013June 1, 2018. Published December 2013June 2018. Originally approved in 1982. Last previous edition approved in 20082013 as
F791 – 96(2008).(2013). DOI: 10.1520/F0791-96R13.10.1520/F0791-18.
2
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.
3
Available from Aircraft Industries Association, 1725 DeSales St. NW, Washington, DC 20034.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F791 − 18
5. Apparatus
5.1 Test Fixture, with fluorescent light source illustrated and constructed as shown in Figs. 1 and 2.
5.2 Drill Fixture constructed as shown in Fig. 3.
5.3 Marking Fixture, constructed as shown in Fig. 3.
5.4 Portable Specimen Rack, constructed in the manner as shown in Fig. 4 for handling and conditioning test specimens.
5.5 Weights—A container and shot for the application of weight on the rack
...