ASTM D6720-01
(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)
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.
1.5 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
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D6720–01
Standard Test Method for
Evaluation of Recoverable Stretch of Stretch Yarns (Skein
Method)
This standard is issued under the fixed designation D 6720; 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 3.1.2.1 Discussion—The recoverable stretch of a yarn is
expressed as a percentage of the recovery length.
1.1 This test method covers the determination of the recov-
3.1.3 stretch yarn, n—a generic term for filament or spun
erable stretch of commercial textured yarns, covered elasto-
yarns having a high degree of potential elastic stretch and a
meric yarns and other stretch yarns using skeins. This test
rapid recovery.
method is particularly valuable for yarns that develop addi-
3.1.3.1 Discussion—Stretch yarns are generally produced
tional crimp upon exposure to hot, wet conditions. The
by an appropriate combination of deforming, heat setting, and
recoverable stretch is a relative measure of the recovery power
developing treatments to attain elastic properties.
the yarn can be expected to provide in a finished fabric.
1.2 This test method is applicable to continuous filament
4. Summary of Test Method
yarns and is suitable for yarns that develop additional stretch
4.1 A skein of yarn is prepared by winding a prescribed
potential upon exposure to heat.
number of turns on a reel in order to obtain a 5000 g skein.The
1.3 This method is applicable to yarns 500 denier or finer.
skein is immersed in boiling water for 15 min and air dried to
1.4 The values stated in SI units are to be regarded as
allow the yarn skein to fully develop its stretch (crimp)
standard. The values given in parentheses are provided for
potential. The skein is exercised under a specified tension and
information only.
its extended length is recorded.Alessor tension is then applied
1.5 This standard does not purport to address all of the
to the skein and its recovery length is recorded. The recover-
safety concerns, if any, associated with its use. It is the
able stretch is calculated from the difference between the
responsibility of the user of this standard to establish appro-
recorded length measurements and expressed as a percentage
priate safety and health practices and determine the applica-
of the recovery length.
bility of regulatory limitations prior to use.
5. Significance and Use
2. Referenced Documents
5.1 This test method is considered satisfactory for accep-
2.1 ASTM Standards:
2 tance testing of commercial shipments because current esti-
D 123 Terminology Relating to Textiles
2 mates of between-laboratory precision are acceptable and the
D 1776 Practice for Conditioning and Testing Textiles
method is used extensively in the trade for acceptance testing.
3. Terminology 5.1.1 If there are differences of practical significance be-
tween reported test results for two laboratories (or more),
3.1 Definitions:
comparative tests should be performed to determine if there is
3.1.1 elastomeric yarn, n—a nontextured yarn which can be
a statistical bias between them, using competent statistical
stretched repeatedly at room temperature to at least twice its
assistance. As a minimum, use samples for such comparative
originallengthandwhichafterremovalofthetensileforcewill
teststhatareashomogeneousaspossible,drawnfromthesame
immediately and forcibly return to approximately its original
lot of material as the samples that resulted in disparate results
length.
during initial testing, and randomly assigned in equal numbers
3.1.2 recoverable stretch, n—the difference between a
to each laboratory. The test results from the laboratories
length of yarn fully extended under a specified force and its
involved should be compared using a statistical test for
recovery under a lesser specified force.
unpaired data, at a probability level chosen prior to the testing
series. If bias is found, either its cause must be found and
This test method is under the jurisdiction ofASTM Committee D13 onTextiles corrected, or future test results for that material must be
and is the direct responsibility of Subcommittee D13.58 on Yarns.
adjusted in consideration of the known bias.
Current edition approved Sept. 10, 2001. Published October 2001.
Annual Book of ASTM Standards, Vol 07.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6720
5.2 This test differs from other crimp contraction test 10.2 Ensure that water bath temperature measuring devices
methods in that it measures the recoverable stretch during the are within calibration.
unload cycle of the yarn.
10.3 Bring bath water to 100° 6 1°C (212° 6 2°F).
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° 6 2°F) for 15 min to allow development of crimp
weight is lifted beyond this point, a false reading will result
potential.
since the yarn will be on the next cycle load extension force.
11.2 Air dry the skeins on the rack and conditioned as
directed in 9.2.
7. Apparatus
11.3 After drying, hang each skein on the meter stick hooks.
7.1 Reel—Ahandormotordrivenreelhavingaperimeterof
11.4 Gently, apply both the 30 g and 1000 g tension weights
1.37 m (54 in.).
to the bottom of the skein.
7.2 Water Bath Tank, filled with water, minimum dimen-
11.5 After about 10 s, allow the skein to relax by manually
sions, 50 l capable of maintaining 100° 6 1°C (212° 6 2°F),
supporting the weights by hand, so that it becomes slack.
for boiling off skeins.
7.3 Rack, having parallel pegs or bars placed a sufficient 11.6 After 10 s, allow the skein to gently extend downward
distance apart to hold the skeins extended to nearly their full under the 1030 g weight.
length without stretching, kinking or entangling the yarns.
11.7 After about 10 s, allow the skein to relax by manually
7.4 Measuring Scales, consisting of one meter stick or other
supporting the weights by hand, so that it becomes slack.
scale for each peg position on the rack, having measuring
11.8 After 10 s, reapply the force by letting the skein gently
intervals of 1 mm (0.05 in.), mounted vertically with a hook at
extend under the weight of the 1030 g force.
the top aligned with the scales 0 position.
11.9 After 10 s, record the extended length, L , to the
7.5 Clock or Stopwatch, with second intervals.
nearest 1 mm (0.05 in.) while under the 1030 g tension.
7.6 Tension Weights—A 30 g weight and either a 1000 g or
11.10 Place two fingers into the bottom of the skein loop
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.