ASTM D6720-07
(Test Method)Standard Test Method for Evaluation of Recoverable Stretch of Stretch Yarns (Skein Method)
Standard Test Method for Evaluation of Recoverable Stretch of Stretch Yarns (Skein Method)
SIGNIFICANCE AND USE
This test method is considered satisfactory for acceptance testing of commercial shipments because current estimates of between-laboratory precision are acceptable and the method is used extensively in the trade for acceptance testing.
5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, use samples for such comparative tests that are as homogeneous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing, and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.
This test differs from other crimp contraction test methods in that it measures the recoverable stretch during the unload cycle of the yarn.
SCOPE
1.1 This test method covers the determination of the recoverable stretch of commercial textured yarns, covered elastomeric yarns and other stretch yarns using skeins. This test method is particularly valuable for yarns that develop additional crimp upon exposure to hot, wet conditions. The recoverable stretch is a relative measure of the recovery power the yarn can be expected to provide in a finished fabric.
1.2 This test method is applicable to continuous filament yarns and is suitable for yarns that develop additional stretch potential upon exposure to heat.
1.3 This method is applicable to yarns 500 denier or finer.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only.
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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D6720–07
Standard Test Method for
Evaluation of Recoverable Stretch of Stretch Yarns (Skein
1
Method)
This standard is issued under the fixed designation D6720; 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 3.1.1 The following terms are relevant to this standard:
elastomeric yarn, recoverable stretch, stretch yarn.
1.1 This test method covers the determination of the recov-
3.2 For all other terms are related to textiles, refer to
erable stretch of commercial textured yarns, covered elasto-
Terminology D123.
meric yarns and other stretch yarns using skeins. This test
method is particularly valuable for yarns that develop addi-
4. Summary of Test Method
tional crimp upon exposure to hot, wet conditions. The
4.1 A skein of yarn is prepared by winding a prescribed
recoverable stretch is a relative measure of the recovery power
number of turns on a reel in order to obtain a 5000 g skein.The
the yarn can be expected to provide in a finished fabric.
skein is immersed in boiling water for 15 min and air dried to
1.2 This test method is applicable to continuous filament
allow the yarn skein to fully develop its stretch (crimp)
yarns and is suitable for yarns that develop additional stretch
potential. The skein is exercised under a specified tension and
potential upon exposure to heat.
its extended length is recorded.Alessor tension is then applied
1.3 This method is applicable to yarns 500 denier or finer.
to the skein and its recovery length is recorded. The recover-
1.4 The values stated in SI units are to be regarded as
able stretch is calculated from the difference between the
standard. The values given in parentheses are provided for
recorded length measurements and expressed as a percentage
information only.
of the recovery length.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 This test method is considered satisfactory for accep-
priate safety and health practices and determine the applica-
tance testing of commercial shipments because current esti-
bility of regulatory limitations prior to use.
mates of between-laboratory precision are acceptable and the
2. Referenced Documents method is used extensively in the trade for acceptance testing.
2 5.1.1 If there are differences of practical significance be-
2.1 ASTM Standards:
tween reported test results for two laboratories (or more),
D123 Terminology Relating to Textiles
comparative tests should be performed to determine if there is
D1776 Practice for Conditioning and Testing Textiles
a statistical bias between them, using competent statistical
D4849 Terminology Related to Yarns and Fibers
assistance. As a minimum, use samples for such comparative
3. Terminology teststhatareashomogeneousaspossible,drawnfromthesame
lot of material as the samples that resulted in disparate results
3.1 For all terminology relating to D13.58, Yarns and
during initial testing, and randomly assigned in equal numbers
Fibers, refer to Terminology D4849.
to each laboratory. The test results from the laboratories
involved should be compared using a statistical test for
1
This test method is under the jurisdiction ofASTM Committee D13 onTextiles
unpaired data, at a probability level chosen prior to the testing
and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
series. If bias is found, either its cause must be found and
Current edition approved Jan. 1, 2007. Published January 2007. Originally
corrected, or future test results for that material must be
approved in 2001. Last previous edition approved in 2001 as D6720 – 01. DOI:
10.1520/D6720-07.
adjusted in consideration of the known bias.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2 This test differs from other crimp contraction test
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
methods in that it measures the recoverable stretch during the
Standards volume information, refer to the standard’s Document Summary page on
unload cycle of the yarn.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6720–07
6. Interferences 11. Procedure
6.1 Care should be take to ensure that the skein is not lifted 11.1 Immerse the test specimen skeins in boiling water 100°
past the point where it is supported by the yarn. If the 30 g 6 1°C (212
...
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