ASTM D2256-02(2008)
(Test Method)Standard Test Method for Tensile Properties of Yarns by the Single-Strand Method
Standard Test Method for Tensile Properties of Yarns by the Single-Strand Method
SIGNIFICANCE AND USE
Acceptance Testing—Option A1 of Test Method D 2256 is considered satisfactory for acceptance testing of commercial shipments because the test method has been used extensively in the trade for acceptance testing. However, this statement is not applicable to knot and loop breaking force tests, tests on wet specimens, tests on oven-dried specimens, or tests on specimens exposed to low or high temperatures and should be used with caution for acceptance testing because factual information on between-laboratory precision and bias is not available.
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 the samples for such a 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, a probability level chosen prior to the testing series. If a 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.
Fundamental Properties—The breaking tenacity, calculated from the breaking force and the linear density, and the elongation are fundamental properties that are widely used to establish limitations on yarn processing or conversion and on their end-use applications. Initial modulus is a measure of the resistance of the yarn to extension at forces below the yield point. The chord modulus is used to estimate the resistance to imposed strain. The breaking toughness is a measure of the work necessary to break the yarn.
Comparison to Skein Testing—The single-strand method gives a more accurate measure of b...
SCOPE
1.1 This test method covers the determination of tensile properties of monofilament, multifilament, and spun yarns, either single, plied, or cabled with the exception of yarns that stretch more than 5.0 % when tension is increased from 0.05 to 1.0 cN/tex (0.5 to 1.0 gf/tex).
1.2 This test method covers the measurement of breaking force and elongation of yarns and includes directions for the calculation of breaking tenacity, initial modulus, chord modulus, and breaking toughness.
1.2.1 Options are included for the testing of specimens in: (A) straight, (B) knotted, and (C) looped form.
1.2.2 Conditions of test are included for the testing of specimens that are: (1) conditioned air, (2) wet, not immersed, (3) wet, immersed, (4) oven-dried, (5) exposed to elevated temperature, or (6) exposed to low temperature.
Note 1—Special methods for testing yarns made from specific fibers; namely, glass, flax, hemp, ramie, and kraft paper and for specific products; namely, tire cords and rope, have been published: Test Methods D 885, and Specification D 578.
Note 2—For directions covering the determination of breaking force of yarn by the skein method refer to Test Method D 1578.
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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D2256–02 (Reapproved 2008)
Standard Test Method for
Tensile Properties of Yarns by the Single-Strand Method
This standard is issued under the fixed designation D2256; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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 Organic-Base Fibers
D1578 TestMethodforBreakingStrengthofYarninSkein
1.1 This test method covers the determination of tensile
Form
properties of monofilament, multifilament, and spun yarns,
D1776 Practice for Conditioning and Testing Textiles
either single, plied, or cabled with the exception of yarns that
D2258 Practice for Sampling Yarn for Testing
stretchmorethan5.0%whentensionisincreasedfrom0.05to
D2904 PracticeforInterlaboratoryTestingofaTextileTest
1.0 cN/tex (0.5 to 1.0 gf/tex).
Method that Produces Normally Distributed Data
1.2 This test method covers the measurement of breaking
D2906 Practice for Statements on Precision and Bias for
force and elongation of yarns and includes directions for the
Textiles
calculation of breaking tenacity, initial modulus, chord modu-
D4848 Terminology Related to Force, Deformation and
lus, and breaking toughness.
Related Properties of Textiles
1.2.1 Options are included for the testing of specimens in:
D4849 Terminology Related to Yarns and Fibers
(A) straight, (B) knotted, and (C) looped form.
E178 Practice for Dealing With Outlying Observations
1.2.2 Conditions of test are included for the testing of
specimens that are: (1) conditioned air, (2) wet, not immersed,
3. Terminology
(3) wet, immersed, (4) oven-dried, (5) exposed to elevated
3.1 Definitions:
temperature, or (6) exposed to low temperature.
3.1.1 Refer to Terminology D4848 for definitions of the
NOTE 1—Special methods for testing yarns made from specific fibers;
followingtermsusedinthisstandard:breakingforce,breaking
namely,glass,flax,hemp,ramie,andkraftpaperandforspecificproducts;
strength, breaking tenacity, breaking toughness, chord modu-
namely, tire cords and rope, have been published: Test Methods D885,
lus, elongation, elongation at break, elongation at rupture,
and Specification D578.
initial modulus, knot-breaking force, knot breaking strength,
NOTE 2—Fordirectionscoveringthedeterminationofbreakingforceof
yarn by the skein method refer to Test Method D1578. linear density, loop breaking force, loop-breaking strength,
single-strand breaking force, single-strand breaking strength,
1.3 This standard does not purport to address all of the
strength and tenacity.
safety concerns, if any, associated with its use. It is the
3.1.2 Refer toTerminology D123 andTerminology D4849
responsibility of the user of this standard to establish appro-
and for definitions of other terms used in this standard.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
4.1 Single-strand yarn specimens are broken on a tension
2. Referenced Documents
testing machine at a predetermined elongation rate and the
2.1 ASTM Standards:
breaking force and the elongation at break are determined.
D76 SpecificationforTensileTestingMachinesforTextiles
Elongation at a specified force or the force or tenacity at a
D123 Terminology Relating to Textiles
specified elongation may also be obtained. Breaking force,
D578 Specification for Glass Fiber Strands
breaking tenacity, elongation, initial and chord modulus, and
D885 Test Methods for Tire Cords, Tire Cord Fabrics, and
breaking toughness of the test specimen, in terms of linear
Industrial Filament Yarns Made from Manufactured
density, may be calculated from machine scales, dials, record-
ing charts, or by an interfaced computer.
4.2 This test method offers the following three physical
ThistestmethodisunderthejurisdictionofASTMCommitteeD13onTextiles
and is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers. configurations of the specimen:
Current edition approved July 1, 2008. Published August 2008. Originally
4.2.1 Configuration A, straight.
approved in 1964. Last previous edition approved in 2002 as D2256–02.
4.2.2 Configuration B, knotted.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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
the ASTM website. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2256–02 (2008)
4.2.3 Configuration C, looped. necessary for a given yarn depending upon its structure and
4.3 Thistestmethodalsooffersthefollowingsixconditions composition.Topreventslippageintheclampsordamageasa
of test with respect to moisture content of the specimens at the result of being gripped in the clamps, special clamping
time of testing: adaptations may be necessary with high modulus yarns made
4.3.1 Condition 1, conditioned to moisture equilibrium for from fibers such as glass or aramid or extended chain polyole-
testing with standard atmosphere for testing textiles. fin. Specimen clamping may be modified as required at the
4.3.2 Condition 2, wet not immersed. discretion of the individual laboratory providing a representa-
4.3.3 Condition 3, wet immersed. tive force-elongation curve is obtained. In any event, the
4.3.4 Condition 4, oven-dried. procedure described in this test method for obtaining tensile
4.3.5 Condition 5, high temperature. properties must be maintained.
4.3.6 Condition 6, low temperature. 5.5 Breaking Strength—The breaking strength of a yarn
4.4 A test option is specified by combining a specimen influencesthebreakingstrengthoffabricsmadefromtheyarn,
configuration and a moisture content condition, for example, although the breaking strength of a fabric also depends on its
OptionA1meansastraightspecimenconditionedandtestedin constructionandmaybeaffectedbymanufacturingoperations.
a standard atmosphere for testing textiles. 5.5.1 Because breaking strength for any fiber-type is ap-
4.5 Unless otherwise indicated, the phrase “single-strand
proximately proportional to linear density, strands of different
breaking force” is associated with Option A1. sizes can be compared by converting the observed breaking
strength to breaking tenacity (centinewtons per tex, grams-
5. Significance and Use
force per tex, or grams-force per denier).
5.1 Acceptance Testing—OptionA1ofTestMethodD2256
5.6 Elongation—The elongation of a yarn has an influence
isconsideredsatisfactoryforacceptancetestingofcommercial
on the manufacturing process and the products made. It
shipmentsbecausethetestmethodhasbeenusedextensivelyin
providesanindicationofthelikelystretchbehaviorofgarment
the trade for acceptance testing. However, this statement is not
areas such as knees, elbows, or other points of stress. It also
applicable to knot and loop breaking force tests, tests on wet
provides design criteria for stretch behavior of yarns or cords
specimens, tests on oven-dried specimens, or tests on speci-
used as reinforcement for items such as plastic products, hose,
mens exposed to low or high temperatures and should be used
and tires.
withcautionforacceptancetestingbecausefactualinformation
5.7 Force-Elongation Curve—Force-elongation curves per-
on between-laboratory precision and bias is not available.
mit the calculation of various values, not all of which are
5.1.1 If there are differences of practical significance be-
discussed in this test method, such as elongation at break,
tween reported test results for two laboratories (or more),
elongation at specified force, force at specified elongation,
comparative tests should be performed to determine if there is
initial elastic modulus which is resistance to stretching, com-
a statistical bias between them, using competent statistical
pliance which is ability to yield under stress, and is the
assistance. As a minimum, use the samples for such a com-
reciprocal of the elastic modulus, and area under the curve, a
parativeteststhatareashomogeneousaspossible,drawnfrom
measure of toughness, which is proportional to the work done.
thesamelotofmaterialasthesamplesthatresultedindisparate
NOTE 3—Force-elongation curves can be converted to stress-strain
results during initial testing and randomly assigned in equal
curves if the force is converted to unit stress, such as to centinewtons per
numbers to each laboratory. The test results from the labora-
tex, or pounds per square inch, or pascals, or grams-force per tex, or
tories involved should be compared using a statistical test for
grams-force per denier, and the elongation is based on change per unit
unpaired data, a probability level chosen prior to the testing
length.
series. If a bias is found, either its cause must be found and
5.8 Knot and Loop Breaking Force—The reduction in
corrected, or future test results for that material must be
breaking force due to the presence of a knot or loop is
adjusted in consideration of the known bias.
considered a measure of the brittleness of the yarn. Elongation
5.2 Fundamental Properties—The breaking tenacity, calcu-
in knot or loop tests is not known to have any significance and
lated from the breaking force and the linear density, and the
is not usually reported.
elongation are fundamental properties that are widely used to
5.9 Rate of Operation—In general, the breaking force
establish limitations on yarn processing or conversion and on
decreases slightly as time-to-break increases.
their end-use applications. Initial modulus is a measure of the
5.9.1 Operation of CRT, CRE, and CRL tension testing
resistance of the yarn to extension at forces below the yield
machines at a constant time-to-break has been found to
point. The chord modulus is used to estimate the resistance to
minimize differences in test results between the three types of
imposed strain. The breaking toughness is a measure of the
tensiontestingmachines.Whentensiletestsareperformedata
work necessary to break the yarn.
fixed time-to-break, then reasonable agreement in breaking
5.3 Comparison to Skein Testing—The single-strand
force has generally been found to exist between CRTand CRE
method gives a more accurate measure of breaking force
tension testing machines. Consistent results are also obtained
presentinthematerialthandoestheskeinmethodandusesless
material. The skein-breaking force is always lower than the
sum of the breaking forces of the same number of ends broken
individually.
Tweedie,A.S.,Metton,M.T.,andFry,J.M., Textile Research Journal,Vol29,
5.4 Applicability—Most yarns can be tested by this test
March 1959, pp. 235–251, and Tweedie,A. S., and Metton, M. T., Textile Research
method. Some modification of clamping techniques may be Journal, Vol 29, March 1959, pp. 589–591.
D2256–02 (2008)
between different manufacturers of CRL tension testing ma- machine may be equipped with: (1) clamps having flat-faced
chines when they are operated at the same time-to-break. The jawsor(2)capstan-,drum-,orsnubbing-typeclamps(Note5).
agreement is not necessarily good, however, between CRE or Automatic (self-loading and recording) single-end tension
CRT tension testing machines on the one hand and CRL testing machines may be used, provided they meet the require-
tension testing machines on the other even when they are all ments as to gage length, rate of operation, and accuracy of
operated at the same time-to-break.The CRE-type tester is the calibration. The tension testing machine may be interfaced
preferred tension testing machine. with a computer system for operation and data gathering. The
5.9.2 Thistestmethodspecifiesanaveragetime-to-breakof CRE-type tension testing machine is recommended unless
20 6 3 s as recommended by ISO TC 38 on Textiles, The otherwise agreed upon between the purchaser and the supplier.
International Standards Association test committee for stan-
NOTE 4—Test machines capable of both tension and compression are
dardizingtestsforfibers,yarns,andfabrics.Italsoprovidesfor
acceptable for use withTest Method D2256 when operated in the tension
alternate speeds, such as 300 6 10 mm (12 6 0.5 in.)/min
mode.
when using a 250-mm (10-in.) gage length. See 9.2.
NOTE 5—Flat-faced clamps are usually used with fine yarns. The
5.9.3 The tolerance of 63 s for the time-to-break is wide snubbing-typeclampsareusedwithcoarseyarnsoryarnsthatshowahigh
breaking force. They are also used when specimens slip in the clamps or
enough to permit convenient adjustment of the tension testing
the number of breaks at or close to the jaws exceeds statistical expecta-
machine’s rate of operation, and it is narrow enough to ensure
tions.Tocheckslippage,makeamarkonthespecimenascloseaspossible
goodagreementbetweentests.Thedifferenceinbreakingforce
tothebackofeachclamp,operatethemachinetobreakthespecimen,and
between tests at 17 and 23 s will usually not exceed 1.5% of
observe whether the marks have moved from the jaw faces of either
the higher value.
clamp.
5.9.4 In case a tension testing machine is not capable of
6.1.1 Recorders on tension testing machines must have
being operated at 20-s time-to-break, alternative rates of
adequate pen response to properly record the force-elongation
operation are included in this test method. These alternative
curve as specified in SpecificationD76.
rates may be used only by agreement between the parties
6.2 Tank, that can be fitted to the tension testing machine
concerned or when required in an applicable material specifi-
and used to test specimens while immersed in water.
cation.
6.3 Container, separate from the testing machine for wet-
5.10 Tests on Wet Specimens—Tests on wet specimens are
ting out specimens to be tested without immersion.
usually made only on yarns which show a loss of breaking
6.4 Area-Measuring Device—An integrating accessory to
force when wet or when exposed to high humidity, for
the tension testing machine or a planimeter.
example, yarns made from animal fibers and man-made fibers
6.5 Distilled or Deionized Water and Nonionic Wetting
based on regenerated and modified cellulose. Wet tests are
Agent, for wet specimens only.
made on flax yarns to detect adulteration by failure to show a
6.6 Conditioning Rack and Umbrella Reel (or Holder),on
gain in breaking force.
which specimens, cut to convenient length, may be clamped
5.11 TestsonOven-DriedSpecimensandSpecimensatHigh
and from which they may be taken one at a time without loss
Temperatures—Tests on oven-dried specimens at
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:D2256–97 Designation:D2256–02 (Reapproved 2008)
Standard Test Method for
Tensile Properties of Yarns by the Single-Strand Method
This standard is issued under the fixed designation D2256; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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
1.1 Thistestmethodcoversthedeterminationoftensilepropertiesofmonofilament,multifilament,andspunyarns,eithersingle,
plied, or cabled with the exception of yarns that stretch more than 5.0% when tension is increased from 0.05 to 1.0 cN/tex (0.5
to 1.0 gf/tex).
1.2 This test method covers the measurement of breaking force and elongation of yarns and includes directions for the
calculation of breaking tenacity, initial modulus, chord modulus, and breaking toughness.
1.2.1 Options are included for the testing of specimens in: (A) straight, (B) knotted, and (C) looped form.
1.2.2 Conditions of test are included for the testing of specimens that are: (1) conditioned air, (2) wet, not immersed, (3) wet,
immersed, (4) oven-dried, (5) exposed to elevated temperature, or (6) exposed to low temperature.
NOTE 1—Special methods for testing yarns made from specific fibers; namely, asbestos, glass, flax, hemp, ramie, and kraft paper and for specific
products; namely, tire cords and rope, have been published: Test Methods D885, Specification D299, and Specification D578.
NOTE 2—For directions covering the determination of breaking force of yarn by the skein method refer to Test Method D1578.
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 appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D76 Specifications for Tensile Testing Machines for Textiles
D123Terminology Relating to Textiles
D299Specification for Asbestos Yarns Terminology Relating to Textiles
D578 Specification for Glass Fiber Yarns Strands
D885Methods of Testing Test Methods for Tire Cords, Tire Cord Fabrics, and Industrial Filament Yarns Made from
Manufactured Organic-Base Fibers
D1578 Test Method for Breaking Strength of Yarn in Skein Form
D1776Practice for Conditioning Textiles for Testing
D2101Test Method for Tensile Properties of Single Man-Made Textile Fibers Taken from Yarns and Tows Practice for
Conditioning and Testing Textiles
D2258 Practice for Sampling Yarn for Testing
D2904 Practice for Interlaboratory Testing of a Textile Test Method that Produces Normally Distributed Data
D2906Practice for Statements on Precision and Bias for Textiles Practice for Statements on Precision and Bias for Textiles
D4848 Terminology Related to Force, Deformation and Related Properties of Textiles
D4849 Terminology Related to Yarns and Fibers
E178 Practice for Dealing withWith Outlying Observations
3. Terminology
3.1 Definitions:
ThistestmethodisunderthejurisdictionofASTMCommitteeD-13onTextilesandisthedirectresponsibilityofSubcommitteeD13.58onYarnTestMethods,General.
Current edition approved Jan 10, 1997. Published March 1997. Originally published as D2256–64 T. Last previous edition D2256–95a.
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, 2008. Published August 2008. Originally approved in 1964. Last previous edition approved in 2002 as D2256–02.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
, Vol 7.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2256–02 (2008)
3.1.1breaking force, n—the maximum force applied to a material carried to rupture. (Compare breaking point, breaking
strength. Syn., force at break).
3.1.2breaking strength, n—strength expressed in terms of the breaking force. (See also breaking force and strength. Syn.,
strength at break).
3.1.3breaking tenacity, n—the tenacity at the breaking force. See also breaking force, tenacity .
3.1.3.1Discussion—Breakingtenacitycommonlyisexpressedascentinewton/ptex(cN/tex)orgram-force/pdenier(gf/den).The
breakingtenacityiseitheracalculatedvalueusingthebreakingforceandlineardensityoftheunstrainedspecimenordirectlyfrom
the tensile machines that can be adjusted suitably to indicate tenacity instead of force for specimens of known linear density.
3.1.4breaking toughness, n—toughness up to the breaking force of a material.
3.1.4.1Discussion—Breaking toughness is proportional to the area under the force-elongation curve from the origin to the
breaking force. In textile strands, it is expressed as work (joules)/punit linear density.
3.1.5chord modulus, n— in a stress-strain curve, the ratio of the change in stress to the change in strain between two specified
points on the curve.
3.1.5.1Discussion—The chord modulus is expressed in centinewton/p tex (cN/tex) or in gram-force/p denier (gf/den).
3.1.6elongation,n—theratiooftheextensionofamaterialtothelengthofthematerialpriortostretchingexpressedasapercent.
3.1.6.1Discussion—Elongation may be measured at any specified force or at rupture.
3.1.7elongation at break, n—the elongation corresponding to the breaking force. (Compare elongation at rupture. See also
elongation. Syn., breaking elongation.)
3.1.8elongation at rupture, n—the elongation corresponding to the force-at-rupture. (Compare elongation at break.)
3.1.9initial modulus, n— in a stress-strain curve, the slope of the initial straight-line portion of the curve.
3.1.9.1Discussion—The initial modulus usually is expressed in centinewton/ptex (cN/tex) or in gram-force/pdenier (gf/den).
3.1.10knot breaking force, n— in tensile testing, the breaking force of a strand having a specified knot configuration tied in the
portion of the strand mounted between the clamps of a tensile testing machine. (Compare knot breaking strength .) See also
breaking force.
3.1.11knot breaking strength, n—strength expressed in terms of the knot breaking force. See also knot breaking force.
3.1.12linear density, n—mass per unit length.
3.1.12.1Discussion—The tex unit (g/Km) is preferred over the denier unit (g/9 Km).
3.1.13loop breaking force, n— in tensile testing, the breaking force of a specimen consisting of two lengths of strand from the
same supply looped together in a specified configuration and mounted between the clamps of a tensile testing machine. (Compare
loop breaking strength.) See also breaking force.
3.1.14loop breaking strength, n—strengthexpressedintermsoftheloopbrakingforce.Seealso loop breaking force, strength.
3.1.15single-strand breaking force, n—in tensile testing, the breaking force of one strand that follows a specified path, usually
a straight line, between the clamps of a tensile testing machine. (Compare breaking force.)
3.1.16single-strand breaking strength, n— strength expressed in terms of the single-strand breaking force. See also
single-strand breaking force, strength.
3.1.17strength, n—the property of a material that resists deformation induced by external forces. (Compare force.)
3.1.18tenacity, n—in a tensile test, the force exerted on the specimen based on the linear density of the unstrained material.
3.1.19For definitions of other textile terms used in this test method, refer to Terminology D123. For definitions of force,
deformation and related properties, refer to Terminology D4848. Definitions:
3.1.1 Refer to Terminology D4848 for definitions of the following terms used in this standard: breaking force, breaking
strength, breaking tenacity, breaking toughness, chord modulus, elongation, elongation at break, elongation at rupture, initial
modulus, knot-breaking force, knot breaking strength, linear density, loop breaking force, loop-breaking strength, single-strand
breaking force, single-strand breaking strength, strength and tenacity.
3.1.2 Refer to Terminology D123 and Terminology D4849 and for definitions of other terms used in this standard.
4. Summary of Test Method
4.1 Single-strand yarn specimens are broken on a tension testing machine at a predetermined elongation rate and the breaking
force and the elongation at break are determined. Elongation at a specified force or the force or tenacity at a specified elongation
may also be obtained. Breaking force, breaking tenacity, elongation, initial and chord modulus, and breaking toughness of the test
specimen,intermsoflineardensity,maybecalculatedfrommachinescales,dials,recordingcharts,orbyaninterfacedcomputer.
4.2 This test method offers the following three physical configurations of the specimen:
4.2.1 Configuration A, straight.
4.2.2 Configuration B, knotted.
4.2.3 Configuration C, looped.
4.3 Thistestmethodalsooffersthefollowingsixconditionsoftestwithrespecttomoisturecontentofthespecimensatthetime
of testing:
4.3.1 Condition 1, conditioned to moisture equilibrium for testing with standard atmosphere for testing textiles.
4.3.2 Condition 2, wet not immersed.
4.3.3 Condition 3, wet immersed.
D2256–02 (2008)
4.3.4 Condition 4, oven-dried.
4.3.5 Condition 5, high temperature.
4.3.6 Condition 6, low temperature.
4.4 A test option is specified by combining a specimen configuration and a moisture content condition, for example, Option
Annex A1 means a straight specimen conditioned and tested in a standard atmosphere for testing textiles.
4.5 Unless otherwise indicated, the phrase “single-strand breaking force” is associated with Option Annex A1. A1.
5. Significance and Use
5.1 Acceptance Testing—Option A1 of Test Method D2256 is considered satisfactory for acceptance testing of commercial
shipments sincebecause the test method has been used extensively in the trade for acceptance testing. However, this statement is
not applicable to knot and loop breaking force tests, tests on wet specimens, tests on oven-dried specimens, or tests on specimens
exposed to low or high temperatures. The procedures in this test methodtemperatures and should be used with caution for
acceptance testing because factual information on between-laboratory precision and bias is not available.
5.1.1 In cases of a dispute arising from differences in reported test results when using this test method for acceptance testing
ofcommercialshipments,thepurchaserandthesuppliershouldconductcomparativeteststodetermineifthereisastatisticalbias
between their laboratories. Competent statistical assistance is recommended for the investigation of bias.As a minimum, the two
parties should take a group of test specimens which are as homogeneous as possible and which are from a lot of material of the
typeinquestion.Thetestspecimensshouldthenberandomlyassignedinequalnumberstoeachlaboratoryfortesting.Theaverage
results from the two laboratories should be compared using appropriate statistical analysis for unpaired data and an acceptable
probabilitylevelchosenbythetwopartiesbeforethetestingbegins.Ifabiasisfound,eitheritscausemustbefoundandcorrected
or the purchaser and the supplier must agree to interpret future test results in the light of the known bias. If there are differences
of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to
determineifthereisastatisticalbiasbetweenthem,usingcompetentstatisticalassistance.Asaminimum,usethesamplesforsuch
a 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, a probability level chosen prior to the testing
series. If a 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 Fundamental Properties—The breaking tenacity, calculated from the breaking force and the linear density, and the
elongation are fundamental properties that are widely used to establish limitations on yarn processing or conversion and on their
end-use applications. Initial modulus is a measure of the resistance of the yarn to extension at forces below the yield point. The
chord modulus is used to estimate the resistance to imposed strain. The breaking toughness is a measure of the work necessary
to break the yarn.
5.3 Comparison to Skein Testing—The single-strand method gives a more accurate measure of breaking force present in the
materialthandoestheskeinmethodanduseslessmaterial.Theskein-breakingforceisalwayslowerthanthesumofthebreaking
forces of the same number of ends broken individually.
5.4 Applicability—Most yarns can be tested by this test method. Some modification of clamping techniques may be necessary
for a given yarn depending upon its structure and composition. To prevent slippage in the clamps or damage as a result of being
gripped in the clamps, special clamping adaptations may be necessary with high modulus yarns made from fibers such as glass
or aramid or extended chain polyolefin. Specimen clamping may be modified as required at the discretion of the individual
laboratory providing a representative force-elongation curve is obtained. In any event, the procedure described in this test method
for obtaining tensile properties must be maintained.
5.5 BreakingStrength—Thebreakingstrengthofayarninfluencesthebreakingstrengthoffabricsmadefromtheyarn,although
the breaking strength of a fabric also depends on its construction and may be affected by manufacturing operations.
5.5.1Since 5.5.1 Because breaking strength for any fiber-type breaking strength is approximately proportional to linear density,
strandsofdifferentsizescanbecomparedbyconvertingtheobservedbreakingstrengthtobreakingtenacity(centinewtonspertex,
grams-force per tex, or grams-force per denier).
5.6 Elongation—The elongation of a yarn has an influence on the manuf
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