ASTM D2731-15

Standard Test Method for Elastic Properties of Elastomeric Yarns (CRE Type Tensile Testing Machines)

SIGNIFICANCE AND USE
5.1 This test method is considered satisfactory for acceptance testing of commercial shipments since 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.  
5.2 Force at Specified Elongation (FASE) is a measure of the tensile force required to extend a textile material within specified limits. This characteristic of elastomeric yarn indicates the resistance that will have to be overcome by the wearer while putting on a garment made of the material and is also an indication of the garment's resistance to deformation caused by normal body movements during wear. The elongations used for these measurements are typically 100 %, 200 % and 300 %.  
5.3 Permanent Deformation (set) is a measure of the increase in length of an elastomeric yarn resulting from cyclic stretching and relaxation. The characteristic is a visible indication of the realignment of intermolecular bonds within the elastic material. As with stress decay, the amount of set increases with yarn extension; however, for any particular extension, little or no additional set takes place after five c...
SCOPE
1.1 This test method covers the determination of elastic properties of “as produced” elastomeric yarns made from rubber, spandex or other elastomers. Elastic properties include force at specified elongations, permanent deformation and stress decay. Other hysteresis related properties can be calculated.
Note 1: For a method designed specifically for testing rubber threads, refer to Test Method D2433.  
1.2 This test method is not applicable to covered, wrapped, or core-spun yarns or yarns spun from elastomeric staple.  
1.3 This test method is applicable to elastomeric yarns having a range of 40 to 3200 dtex (36 to 2900 denier).  
1.4 The values stated in either SI units or U.S. Customary units are to be regarded separately as standard. Within the text, the U.S. Customary units are in parentheses. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other.  
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

• Status: Historical
• Publication Date: 31-Jan-2015
• ICS: 59.080.20 - Yarns
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.58 - Yarns and Fibers

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: D2731 − 15
Standard Test Method for
Elastic Properties of Elastomeric Yarns (CRE Type Tensile
1
Testing Machines)
This standard is issued under the fixed designation D2731; 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.
3
1. Scope D2433 Test Methods for Rubber Thread (Withdrawn 2012)
D2591 Test Method for Linear Density of ElastomericYarns
1.1 This test method covers the determination of elastic
(Short Length Specimens)
properties of “as produced” elastomeric yarns made from
D2653 Test Method for Tensile Properties of Elastomeric
rubber, spandex or other elastomers. Elastic properties include
Yarns (CRE Type Tensile Testing Machines)
force at specified elongations, permanent deformation and
D4848 Terminology Related to Force, Deformation and
stress decay. Other hysteresis related properties can be calcu-
Related Properties of Textiles
lated.
D4849 Terminology Related to Yarns and Fibers
NOTE 1—For a method designed specifically for testing rubber threads,
D6717 Test Method for Linear Density of ElastomericYarns
refer to Test Method D2433.
(Skein Specimens)
1.2 This test method is not applicable to covered, wrapped,
3. Terminology
or core-spun yarns or yarns spun from elastomeric staple.
3.1 For all terminology relating to D13.58, Yarns and
1.3 This test method is applicable to elastomeric yarns
Fibers, refer to Terminology D4849.
having a range of 40 to 3200 dtex (36 to 2900 denier).
3.1.1 The following terms are relevant to this standard:
1.4 The values stated in either SI units or U.S. Customary
deformation, elastomeric yarn, elongation, force at specified
units are to be regarded separately as standard. Within the text,
elongation,lineardensity,permanentdeformation,stress,stress
the U.S. Customary units are in parentheses. The values stated
decay.
in each system are not exact equivalents; therefore, each
3.2 For definitions of other terms related to force and
system shall be used independently of the other.
deformation, refer to Terminology D4848. For all other terms
1.5 This standard does not purport to address all of the
related to textiles, refer to Terminology D123.
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4.1 Aspecimen, mounted in a CRE-type tensile machine, is
bility of regulatory limitations prior to use.
initially subjected to a series of five loading/unloading cycles
in which the specimen is extended and relaxed between zero
2. Referenced Documents
and 75 % of the elongation at first filament break (FFB).
2
During the fifth cycle, the specimen is held at the maximum
2.1 ASTM Standards:
extension point for 30 s, then unloaded to allow a return to its
D76 Specification for Tensile Testing Machines for Textiles
original gage length position. The specimen is then subjected
D123 Terminology Relating to Textiles
to a sixth load/unload cycle.
D1776 Practice for Conditioning and Testing Textiles
D2258 Practice for Sampling Yarn for Testing
4.2 Force at specified elongations are calculated from the
force-elongation curve for the first and fifth loadings and for
thefifthunloading.Stressdecayiscalculatedonthefifthcycle.
Extension at a specified force is determined on the sixth
loading and is used to calculate the permanent deformation.
1
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
5. Significance and Use
Current edition approved Feb. 1, 2015. Published March 2015. Originally
approved in 1968. Last previous edition approved in 2012 as D2731–07(2012).
5.1 This test method is considered satisfactory for accep-
DOI: 10.1520/D2731-15.
tance testing of commercial shipments since current estimates
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
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D2731 − 15
of between-laboratory precision are acceptable and the method ofcycling,anddesignedforoperationatapullingspeedof500
is used extensively in the trade for acceptance testing. mm/min (20 in./min).
5.1.1 If there are differences of
...

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: D2731 − 07 (Reapproved 2012) D2731 − 15
Standard Test Method for
Elastic Properties of Elastomeric Yarns (CRE Type Tensile
1
Testing Machines)
This standard is issued under the fixed designation D2731; 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
1.1 This test method covers the determination of elastic properties of “as produced” elastomeric yarns made from rubber,
spandex or other elastomers. Elastic properties include force at specified elongations, permanent deformation and stress decay.
Other hysteresis related properties can be calculated.
NOTE 1—For a method designed specifically for testing rubber threads, refer to Test Method D2433.
1.2 This test method is not applicable to covered, wrapped, or core-spun yarns or yarns spun from elastomeric staple.
1.3 This test method is applicable to elastomeric yarns having a range of 40 to 3200 dtex (36 to 2900 denier).
1.4 The values stated in either SI units or U.S. Customary units are to be regarded separately as standard. Within the text, the
U.S. Customary units are in parentheses. The values stated in each system are not exact equivalents; therefore, each system shall
be used independently of the other.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
D76 Specification for Tensile Testing Machines for Textiles
D123 Terminology Relating to Textiles
D1776 Practice for Conditioning and Testing Textiles
D2258 Practice for Sampling Yarn for Testing
3
D2433 Test Methods for Rubber Thread (Withdrawn 2012)
D2591 Test Method for Linear Density of Elastomeric Yarns (Short Length Specimens)
D2653 Test Method for Tensile Properties of Elastomeric Yarns (CRE Type Tensile Testing Machines)
D4848 Terminology Related to Force, Deformation and Related Properties of Textiles
D4849 Terminology Related to Yarns and Fibers
D6717 Test Method for Linear Density of Elastomeric Yarns (Skein Specimens)
3. Terminology
3.1 For all terminology relating to D13.58, Yarns and Fibers, refer to Terminology D4849.
3.1.1 The following terms are relevant to this standard: deformation, elastomeric yarn, elongation, force at specified elongation,
linear density, permanent deformation, stress, stress decay.
3.2 For definitions of other terms related to force and deformation, refer to Terminology D4848. For all other terms related to
textiles, refer to Terminology D123.
1
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.
Current edition approved July 1, 2012Feb. 1, 2015. Published August 2012March 2015. Originally approved in 1968. Discontinued 1979 and reinstated as D2731 – 01.Last
previous edition approved in 20072012 as D2731D2731–07(2012).–07. DOI: 10.1520/D2731-07R12.10.1520/D2731-15.
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
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D2731 − 15
4. Summary of Test Method
4.1 A specimen, mounted in a CRE-type tensile machine, is initially subjected to a series of five loading/unloading cycles in
which the specimen is extended and relaxed between zero and 75 % of the elongation at first filament break (FFB). During the fifth
cycle, the specimen is held at the maximum extension point for 30 s, then unloaded to allow a return to its original gage length
position. The specimen is then subjected to a sixth load/unload cycle.
4.2 Force at specified elongations are calculated from the force-elongation curve for the first and fifth loadings and for the fifth
unloading. Stress decay is calculated on the fifth cycle. Extension at a specified force is determined on the sixth loading
...