ASTM D1445/D1445M-12(2021)
(Test Method)Standard Test Method for Breaking Strength and Elongation of Cotton Fibers (Flat Bundle Method)
Standard Test Method for Breaking Strength and Elongation of Cotton Fibers (Flat Bundle Method)
SIGNIFICANCE AND USE
5.1 This test method is considered satisfactory for acceptance testing when the levels of the laboratories are controlled by the use of the same reference standard cotton samples because the current estimates of between-laboratory precision are acceptable under these conditions. 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, ensure the test samples to be used are as homogeneous as possible, are drawn from the material from which the disparate test results were obtained, and are randomly assigned in equal numbers to each laboratory for testing. The test from the two laboratories should be compared using a statistical test for unpaired data, at 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 This test method is useful in research studies to determine the influence of variety, environment, and processing on fiber strength and elongation; and in studies of the relationships between these fiber properties, processing performance, and quality of end-product.
5.3 Values obtained for flat bundle tenacity and elongation show a high correlation with values measured on single fibers and require much less time and skill.
5.4 Studies have shown that strength measurements obtained with different types of instruments are highly correlated, but the results are on different levels.3
5.5 By use of correction factors calculated from tests made on standard calibration samples of known or established test values, the results obtained with different types of instruments at a specified gauge length can be adjusted to comparable levels. Due to the normal variation in cottons, strength test results...
SCOPE
1.1 This test method covers the determination of (1) the tensile strength or breaking tenacity of cotton fibers as a flat bundle using a nominal zero gauge length, or (2) the tensile strength or breaking tenacity and the elongation at the breaking load of cotton fibers as a flat bundle with 1/8-in. [3.2-mm] clamp spacing. This test method is applicable to loose ginned cotton fibers of untreated cottons whether taken before processing or obtained from a textile product.
1.2 This test method is designed primarily for use with special fiber bundle clamps and special strength testing instruments but may be used with other tensile strength and elongation testing machines when equipped with appropriate adapters to accommodate the fiber clamps.
Note 1: Other methods for measuring the breaking tenacity of fiber bundles include Test Method D1294, Test for Breaking Strength of Wool Fiber Bundles—1 in gauge Length;2 and D5867, Test Method for Measurement of Physical Properties of Cotton Fibers by High Volume Instruments.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barr...
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1445/D1445M − 12 (Reapproved 2021)
Standard Test Method for
Breaking Strength and Elongation of Cotton Fibers (Flat
Bundle Method)
This standard is issued under the fixed designation D1445/D1445M; 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.
INTRODUCTION
The flat bundle test for cotton fiber strength gained immediate acceptance after its introduction in
1953.Thefirstsuccessfulinstrumentwasaninclinedplanedevicewiththebeamcalibratedinpounds.
The specimen was clamped with no space between the jaws and was called zero-gauge strength.
Results were expressed in Pressley Index (P.I.) calculated as the force-to-break in pounds divided by
the bundle weight in mg. Obviously, P.I. is not a standard engineering unit.
Before the introduction of the flat bundle test, cotton fiber strength had been measured by the
Chandler round bundle test (see former Method D414) and the results expressed in pounds per square
inch [psi]. The U.S. Department ofAgriculture obtained results from both instruments on specimens
fromthesamesamplesofalargenumberofcottons.Fromthisstudy,anempiricalequationtoexpress
flat bundle test results in psi was:
Breaking strength, 1000 psi = (10.81106 × P.I.) – 0.12
Whenitwasshownthatafinitegaugelengthtestwasmorehighlycorrelatedwithyarnstrengththan
tests made at zero gauge length, the clamp design was modified to accommodate a ⁄8 in. [3.2 mm]
spacer. Selection of an engineering unit for reporting of results from ⁄8 in. [3.2 mm] gauge tests
presentedaproblem.However,theuseofthetexforlineardensityandtheintroductionofapendulum
typeinstrumentcalibratedinkilogramsledtotheexpressionofresultsingrams-forcepertex[gf/tex].
The clamp width without spacer is 11.81 mm and with spacer is 15.00 mm. The bundle of fibers is
mounted across the clamp width and trimmed to the width. The bundle mass is mg/11.81 mm or
mg/15.00 mm.
Theuseoftheflatbundletestindomesticandinternationalcommercehashadalongandsuccessful
history. Correcting this error in the empirical relationship would have serious adverse affects in the
textile industry. Therefore, the empirical relationship is retained to calculate zero gauge cotton fiber
tensile strength designated as the Pressley strength in Eq 3 and 4 of D1445/D1445M.
1. Scope ments but may be used with other tensile strength and
elongation testing machines when equipped with appropriate
1.1 This test method covers the determination of (1) the
adapters to accommodate the fiber clamps.
tensile strength or breaking tenacity of cotton fibers as a flat
bundle using a nominal zero gauge length, or (2) the tensile
NOTE 1—Other methods for measuring the breaking tenacity of fiber
strengthorbreakingtenacityandtheelongationatthebreaking
bundles include Test Method D1294, Test for Breaking Strength of Wool
Fiber Bundles—1 in gauge Length; and D5867, Test Method for
load of cotton fibers as a flat bundle with ⁄8-in. [3.2-mm]
Measurement of Physical Properties of Cotton Fibers by High Volume
clamp spacing. This test method is applicable to loose ginned
Instruments.
cotton fibers of untreated cottons whether taken before pro-
1.3 The values stated in either SI units or inch-pound units
cessing or obtained from a textile product.
are to be regarded separately as standard. The values stated in
1.2 This test method is designed primarily for use with
each system may not be exact equivalents; therefore, each
special fiber bundle clamps and special strength testing instru-
ThismethodisunderthejurisdictionofASTMCommitteeD13onTextilesand
is the direct responsibility of Subcommittee D13.11 on Cotton Fibers. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2021. Published January 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1953. Last previous edition approved in 2012 as D1445–12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D1445_D1445M-12R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1445/D1445M − 12 (2021)
system shall be used independently of the other. Combining are acceptable under these conditions. If there are differences
values from the two systems may result in non-conformance of practical significance between reported test results for two
with the standard. laboratories (or more), comparative tests should be performed
to determine if there is a statistical bias between them, using
1.4 This standard does not purport to address all of the
competent statistical assistance.As a minimum, ensure the test
safety concerns, if any, associated with its use. It is the
samples to be used are as homogeneous as possible, are drawn
responsibility of the user of this standard to establish appro-
from the material from which the disparate test results were
priate safety, health, and environmental practices and deter-
obtained, and are randomly assigned in equal numbers to each
mine the applicability of regulatory limitations prior to use.
laboratoryfortesting.Thetestfromthetwolaboratoriesshould
1.5 This international standard was developed in accor-
be compared using a statistical test for unpaired data, at a
dance with internationally recognized principles on standard-
probability level chosen prior to the testing series. If a bias is
ization established in the Decision on Principles for the
found, either its cause must be found and corrected, or future
Development of International Standards, Guides and Recom-
test results for that material must be adjusted in consideration
mendations issued by the World Trade Organization Technical
of the known bias.
Barriers to Trade (TBT) Committee.
5.2 This test method is useful in research studies to deter-
2. Referenced Documents
mine the influence of variety, environment, and processing on
fiberstrengthandelongation;andinstudiesoftherelationships
2.1 ASTM Standards:
between these fiber properties, processing performance, and
D123Terminology Relating to Textiles
quality of end-product.
D1294Test Method for Tensile Strength and Breaking Te-
nacity of Wool Fiber Bundles 1-in. (25.4-mm) Gage
5.3 Values obtained for flat bundle tenacity and elongation
Length
show a high correlation with values measured on single fibers
D1441Practice for Sampling Cotton Fibers for Testing
and require much less time and skill.
D1447Test Method for Length and Length Uniformity of
5.4 Studies have shown that strength measurements ob-
Cotton Fibers by Photoelectric Measurement
tainedwithdifferenttypesofinstrumentsarehighlycorrelated,
D1776Practice for Conditioning and Testing Textiles
but the results are on different levels.
D3025Practice for Standardizing Cotton Fiber Test Results
5.5 By use of correction factors calculated from tests made
by Use of Calibration Cotton Standards
on standard calibration samples of known or established test
D5867Test Methods for Measurement of Physical Proper-
values, the results obtained with different types of instruments
ties of Raw Cotton by Cotton Classification Instruments
at a specified gauge length can be adjusted to comparable
D7139Terminology for Cotton Fibers
levels. Due to the normal variation in cottons, strength test
3. Terminology
results for one gauge length cannot be reliably estimated from
tests made at a different gauge length.
3.1 For all terminology related to D13.11, see Terminology
D7139 5.6 The terms tensile strength and breaking tenacity are
3.1.1 The following terms are relevant to this standard:
sometimes used interchangeably. They are relational but are
breaking force, breaking tenacity, cotton, elongation at break- not equivalent (see 12.1.1 and 12.1.2). Tenacity is commonly
ing load, tenacity, tensile strength.
expressed as centinewtons per tex (cN/tex), grams-force per
denier (gf/den) or pounds-force per denier (lbf/den). Tenacity
3.2 For all other terminology related to textiles, refer to
in centinewtons/tex is numerically equal to tenacity in grams-
Terminology D123.
force/tex times 0.981.
4. Summary of Test Method
6. Apparatus and Materials
4.1 Abundleofcottonfibersiscombedparallelwiththeaid
6.1 Tensile Testing Machine—Either of two commercially
of specialized clamps to minimize loose fibers that are in the
available fiber bundle tensile testing machines, one of the
bundle, secured in clamps, cut to a known length, broken in a
pendulumtypeandoneoftheinclined-planetype,describedin
tensile testing machine, and weighed. Tensile strength or
AppendixX1,orothermachinefromwhichcomparableresults
breaking tenacity is calculated from the ratio of breaking load
can be obtained.
to bundle mass (weight).
6.2 Laboratory Balance:
4.2 Elongation at the breaking force may be determined on
1 6.2.1 Balance, having a capacity of 3 or 5 mg and a
thespecimenstestedforbreakingstrengthwith ⁄8-in.[3.2-mm]
sensitivity of 60.01 mg for the zero gauge length test.
clamp spacing. The elongation is normally calculated as a
6.2.2 Balance, having a capacity of 5 or 10 mg and a
percentage of the nominal gauge length.
sensitivity of 0.01 mg for ⁄8-in. [3.2-mm] gauge length test.
5. Significance and Use
5.1 This test method is considered satisfactory for accep-
Burley, Jr., S. T., and Carpenter, F., “Evaluation of Results Obtained on
tance testing when the levels of the laboratories are controlled
Available Types of Fiber Strength Testers Using Various Gauge Spacings and Their
by the use of the same reference standard cotton samples
Relation to Yarn Strength,” Textile Research Journal (TRJ), Vol 24, 1954, pp.
because the current estimates of between-laboratory precision 251-260.
D1445/D1445M − 12 (2021)
6.3 Ancillary equipment from the instrument manufactur- do not normally exceed the range of 0.90 to 1.10. When
ers. adjustingtheresultstothemorecommonlyusedstandardlevel
6.3.1 Clamp Vise (Pressley type or Stelometer type), with a for the inclined-plane type testing machine, however, the
device to indicate approximately 8 lbf·in. [9 kgf·cm] torque. correction factor for the pendulum-type testing machine is
6.3.2 Fiber Clamps, having a total thickness of 0.465 6 usually within the range of 1.16 to 1.36. The difference in the
0.001 in. [11.81 6 0.02 mm]. size of the correction factors for the different type testing
6.3.3 Spacer,havingathicknessof0.125 60.001in.[3.2 6 machines is primarily because of a difference in the rate of
0.02 mm]. force.The ⁄8-in. [3.2-mm] gauge test values of the Calibration
6.3.4 Clamp Wrench or Torque Wrench. Cotton Standards for the inclined-plane type testing machine
6.3.5 Coarse Comb, approximately 8 teeth/in. [3 teeth/cm], aregreaterbyafactorof1.26thanthoseforthependulum-type
or Fibrograph comb. testing machine.
6.3.6 Fine Comb, approximately 52 teeth/in. [20 teeth/cm].
6.3.7 Black Paper, to hold bundles. 9. Conditioning
6.3.8 Shearing Knife.
9.1 Bring the laboratory sample from the dry side to
6.3.9 Tweezers.
moisture equilibrium for testing in the standard atmospheres
6.3.10 Standard Calibration Cotton, having specified fiber
for textile testing according to Practice D1776.
strength.
NOTE 2—Cotton is normally received in the laboratory in a relatively
6.3.11 Fiber Clips or Sample Clips.
“dry” condition, making special preconditioning procedures unnecessary.
Samples that are obviously damp should be preconditioned before being
7. Sampling
brought into the laboratory for conditioning.
7.1 Take lot sample and laboratory samples as directed in
Practice D1441.
10. Sampling, Test Specimens and Test Units
8. Preparation, Calibration, and Verification of 10.1 From a conditioned laboratory sample, pull small tufts
Apparatus (pinches) of cotton fibers to make the test specimens (flat
bundles). Tufts taken from Fibrograph beards as prepared by
8.1 Tensile testing instrument—Before making fiber
Test Method D1447 may be used.
strength tests, check the instrument and clamp vise for me-
10.1.1 Prepare a tuft of fibers either (1) by taking two small
chanical adjustment as directed for the specific instrument in
pinches at random from the unblended laboratory sample and
Appendix X1, or in accordance with the manufacturer’s
placing them one on top of the other near their mid-points, or
instructions.
(2)bytakingasectionfromablendedlaboratorysample.Hold
8.2 Laboratory balance—Check the zero setting of the
the tuft between the thumb and forefinger and comb with a
laboratory balance and make sure its sensitivity is within the
coarse comb to remove foreign matter and short fiber. When
range to be used.
oneendofthetufthasbeencombed,reversethetuftandcomb
8.3 Clamp leathers—Inspect the leathers in the clamps the other end, taking care that the fibers in the middle portion
frequently to ensure that they are in good condition. Keep the of the tuft are well combed. Approximately 10 strokes are
inneredgesoftheleatherstrimmedflushwiththemetalsurface necessary for combing each end of the tuft. Prepare two to six
and replace the leathers as soon as grooves are observed. tufts, each weighing 60 to 80 mg, from each sample to be
tested. Before testing, condition the tufts as directed in Section
8.4 Check Test – Use of Standard Calibration Cotton
9.
Samples—Each day before making other tests, make a check
10.1.2 Prepare two to six tufts, each weighing 60 to 80 mg,
test of at least three specimens per technician on one or more
from each laboratory sample or Fibrograph beard to be tested.
standard calibration samples to check the reproducibility and
10.2 Prepare the specimen as directed in either 10.2.1 or
uniformity of results. If available, use standard calibration
samples with test values within the range of the unknown 10.2.2.
10.2.1 Grasp a prepared tuft near the midpoint between the
samples being tested. Make additional check tests in a similar
manner at least three more times during a working day to center and the end of the tuft, and pull out a portion of the
obtain results for the calculation of correction factors. The fiberstoformaspecimen.Holdthespecimenfirmlybyoneend
calculated breaking tenacity or tensile strength values of the and pull the fibers through the fine comb on the vise two or
samples tested during the same time period can be adjusted to three times to remove loose fibers, neps, and trash. Comb the
the standard level by applying the correction facto
...
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