ASTM D3768-96

Standard Test Method for Microcellular Urethanes--Flexural Recovery

SCOPE
1.1 This method covers the procedure and apparatus for measuring the flexural recovery of microcellular urethanes.  
1.2 The values stated in SI units are to be regarded as the standard.  
1.3 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 this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Note 1--There is no similar or equivalent ISO standard to this test method.

General Information

• Status: Historical
• Publication Date: 31-Dec-1999
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Relations

• Replaced By: ASTM D3768-96(2000) - Standard Test Method for Microcellular Urethanes--Flexural Recovery
• Effective Date: 01-Jan-2000
• Referred By: ASTM D3489-23 - Standard Test Methods for Microcellular Urethane Materials
• Effective Date: 01-Jan-2000

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3768 – 96
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Microcellular Urethanes—Flexural Recovery
This standard is issued under the fixed designation D 3768; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the procedure and apparatus for
measuring the flexural recovery of microcellular urethanes.
1.2 The values stated in SI units are to be regarded as the
standard.
1.3 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
NOTE 1—There is no similar or equivalent ISO standard to this test
method.
2. Referenced Documents
2.1 ASTM Standards:
D 3040 Practice for Preparing Precision Statements for
Standards Related to Rubber and Rubber Testing
E 691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
3. Significance and Use
3.1 This test method is used to indicate the ability of a
material to recover after a 180° bend around a 12.7-mm
(0.5-in.) diameter mandrel at room temperature.
3.2 Before proceeding with this test method, reference
should be made to the specification of the material being tested.
FIG. 1 Fixture for Flexural Recovery Test
Any test specimen preparation, conditioning, or dimensions, or
combination thereof, and testing parameters covered in the
materials specification shall take precedence over those men-
4.2 Timer, capable of indicating seconds.
tioned in these test methods. If there are no material specifi-
4.3 Thickness Indicator, accurate to 0.25 mm.
cations, then the default conditions apply.
5. Test Specimens
NOTE 2—This test method may be applied to solid urethanes.
5.1 The test specimens shall be die cut from molded plaques
4. Apparatus
or parts. The specimen size shall be 25 mm in width by 150
4.1 Flexural Recovery Test Fixture—See Fig. 1.
mm in length (1 by 6 in.). The recommended standard test
specimen is 4 mm in thickness. Thinner specimens may be
used, but shall not be less than 3 mm.
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.22 on Cellular Materials—
6. Conditioning
Plastics and Elastomers.
6.1 Unless otherwise specified, condition the specimens and
Current edition approved August 10, 1996. Published February 1997. Originally
published as D 3768 – 79. Last previous edition D 3768 – 85 (1990). fixtures a minimum of1hat23 6 2°C and 50 6 5 % relative
This revision includes the addition of the following: an ISO equivalency
humidity before testing.
statement, a materials specification statement, and a keyword section.
Discontinued—see 1986 Annual Book of ASTM Standards, Vols 09.01 and
7. Procedure
09.02.
Annual Book of ASTM Standards, Vol 14.02. 7.1 There shall be at least three recovery measurements.
D 3768
7.2 Measure the thickness of specimen to the nearest 0.25 9.1.3 Flexural set (30 s), average of three,
mm. 9.1.4 Flexural set (300 s), average of three, and
7.3 Insert the test specimen in the lower slot of the specimen 9.1.5 Sample thickness.
clamp and position the end of the specimen flush with the rear
10. Precision and Bias
face of the bend mandrel. Tighten the clamp while holding the
10.1 Table 1 is based on a round robin conducted in 1980
specimen in a horizontal position. (Do not allow the outer end
of the specimen to be in contact with the base of the test in accordance with Practice D 3040, involving three materials
tested by four laboratories. For each material, all the samples
fixture.) A spacer of approximately the same thickness as the
test specimen must be used in the upper slot to ensure proper were prepared at one source and the individual specimens were
also prepared at one source. Each test result consisted of one
clamping in the lower slot.
7.4 Make an initial reading where the mandrel edge of the individual determination. Each laboratory obtai
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