ASTM F791-96(2008)
(Test Method)Standard Test Method for Stress Crazing of Transparent Plastics
Standard Test Method for Stress Crazing of Transparent Plastics
SIGNIFICANCE AND USE
This test method provides a guide for evaluating a specific solvent, chemical, or compound that may be 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 would cause crazing is applied producing non-reversible damage that might limit 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 and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F791 − 96(Reapproved 2008)
Standard Test Method for
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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 Department of Defense.
1. Scope and scattered with varied lengths and depths but usually are
oriented perpendicular to a tensile stress. Crazing may be
1.1 This test method covers the determination of the critical
difficult to detect. It becomes more pronounced when viewed
crazing stress for a transparent plastic material when exposed
with a light source that is at an oblique angle.
to a specific solvent, chemical, or compound at a specific
temperature.
4. Significance and Use
1.2 This standard does not purport to address all of the
4.1 This test method provides a guide for evaluating a
safety concerns, if any, associated with its use. It is the
specific solvent, chemical, or compound that may be detrimen-
responsibility of the user of this standard to establish appro-
tal to a transparent plastic as a result of a manufacturing
priate safety and health practices and determine the applica-
process, a fabrication operation, or the operational environ-
bility of regulatory limitations prior to use.
ment.Alltransparentplasticsaresusceptibletocrazing,though
inwidelyvaryingdegreeandfromavarietyofcauses.Thistest
2. Referenced Documents
method is intended to allow establishment of the crazing stress
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2.1 ASTM Standards:
when the simultaneous action of both load and a material that
D618 Practice for Conditioning Plastics for Testing
would cause crazing is applied producing non-reversible dam-
E691 Practice for Conducting an Interlaboratory Study to
age that might limit the usage of that transparent plastic in a
Determine the Precision of a Test Method
specific application.
2.2 Other Method:
5. Apparatus
ARTC (Aircraft Research and Testing Committee of the
Aircraft Industries Association of America, Inc.) Condi-
5.1 Test Fixture, with fluorescent light source illustrated and
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tioning Method
constructed as shown in Figs. 1 and 2.
5.2 Drill Fixture constructed as shown in Fig. 3.
3. Terminology
5.3 Marking 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
5.4 Portable Specimen Rack, constructed in the manner as
small cracks in the material, although they are not.
shown in Fig. 4 for handling and conditioning test specimens.
3.1.1.1 Discussion—Crazing is a form of yielding in poly-
5.5 Weights—A container and shot for the application of
mers characterized by a spongy void filled fibrillar structure.
weight on the rack as shown in Fig. 1.
The density in the craze changes resulting in a change in the
5.6 Filter Paper, quantity of 0.50 by 1.0-in. (12.7 by
index of refraction, which causes light to be reflected off of the
25.4-mm) pieces of filter, medium-retention filter paper.
crazes. This light reflection causes the crazes to sparkle when
viewed from certain angles. The crazes are sometimes random
6. Test Specimens
6.1 The test specimen shall be machined from the transpar-
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This test method is under the jurisdiction of ASTM Committee F07 on
ent plastic material to be evaluated. A minimum of six
Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on
specimens for each solvent, chemical, or compound is re-
Transparent Enclosures and Materials.
quired. It is preferred that the transparent plastic sheet material
Current edition approved April 1, 2008. Published April 2008. Originally
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approved in 1982. Last previous edition approved in 2002 as F791 – 96 (2002) .
thickness be 6.35 6 0.64 mm (0.250 6 0.025 in.), but any
DOI: 10.1520/F0791-96R08.
thickness material may be used. Orientation of each test
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
specimen within the test sheet or part should be recorded.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
6.2 Thetestspecimensshallbe25.4 60.8mm(1.00 60.03
the ASTM website.
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in.) wide by 177.8 6 1.27 mm (7.00 6 0.05 in.) long by
Available from Aircraft Industries Association, 1725 DeSales St. NW,
Washington, DC 20034. thickness.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F791 − 96 (2008)
FIG. 1 Accelerated Crazing Test Fixture
FIG. 3 Fixtures for Spe
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