ASTM D1445/D1445M-12(2021)

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...

General Information

• Status: Published
• Publication Date: 31-Dec-2020
• ICS: 59.060.10 - Natural fibres
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.11 - Cotton Fibers

Relations

• Refers: ASTM D1441-12(2020) - Standard Practice for Sampling Cotton Fibers for Testing
• Effective Date: 01-Jul-2020
• Refers: ASTM D5867-12(2020) - Standard Test Methods for Measurement of Physical Properties of Raw Cotton by Cotton Classification Instruments
• Effective Date: 01-Jul-2020
• Refers: ASTM D7139-20 - Standard Terminology for Cotton Fibers
• Effective Date: 01-Jul-2020

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
1
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
1
tests made at zero gauge length, the clamp design was modified to accommodate a ⁄8 in. [3.2 mm]
1
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
2
1
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-
1
ThismethodisunderthejurisdictionofASTMCommitteeD13onTextilesand
2
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 [e-mail]. 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.
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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 res
...