1、Designation:D1445/D1445M12(Reapproved 2021)Standard Test Method forBreaking Strength and Elongation of Cotton Fibers(FlatBundle Method)1This standard is issued under the fixed designation D1445/D1445M;the number immediately following the designation indicates theyear of original adoption or,in the c
2、ase of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe flat bundle test for cotton fiber strength gained immediate acceptance after its introduct
3、ion in1953.The first successful instrument was an inclined plane device with the beam calibrated in pounds.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 bythe
4、 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 theChandler round bundle test(see former Method D414)and the results expressed in pounds per squareinch psi.The U.S.Department of Agricultu
5、re obtained results from both instruments on specimensfrom the same samples of a large number of cottons.From this study,an empirical equation to expressflat bundle test results in psi was:Breaking strength,1000 psi=(10.81106 P.I.)0.12When it was shown that a finite gauge length test was more highly
6、 correlated with yarn strength thantests made at zero gauge length,the clamp design was modified to accommodate a18in.3.2 mmspacer.Selection of an engineering unit for reporting of results from18in.3.2 mm gauge testspresented a problem.However,the use of the tex for linear density and the introducti
7、on of a pendulumtype instrument calibrated in kilograms led to the expression of results in grams-force per tex gf/tex.The clamp width without spacer is 11.81 mm and with spacer is 15.00 mm.The bundle of fibers ismounted across the clamp width and trimmed to the width.The bundle mass is mg/11.81 mm
8、ormg/15.00 mm.The use of the flat bundle test in domestic and international commerce has had a long and successfulhistory.Correcting this error in the empirical relationship would have serious adverse affects in thetextile industry.Therefore,the empirical relationship is retained to calculate zero g
9、auge cotton fibertensile strength designated as the Pressley strength in Eq 3 and 4 of D1445/D1445M.1.Scope1.1 This test method covers the determination of(1)thetensile strength or breaking tenacity of cotton fibers as a flatbundle using a nominal zero gauge length,or(2)the tensilestrength or breaki
10、ng tenacity and the elongation at the breakingload of cotton fibers as a flat bundle with18-in.3.2-mmclamp spacing.This test method is applicable to loose ginnedcotton fibers of untreated cottons whether taken before pro-cessing or obtained from a textile product.1.2 This test method is designed pri
11、marily for use withspecial fiber bundle clamps and special strength testing instru-ments but may be used with other tensile strength andelongation testing machines when equipped with appropriateadapters to accommodate the fiber clamps.NOTE1Other methods for measuring the breaking tenacity of fiberbu
12、ndles include Test Method D1294,Test for Breaking Strength of WoolFiber Bundles1 in gauge Length;2and D5867,Test Method forMeasurement of Physical Properties of Cotton Fibers by High VolumeInstruments.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standa
13、rd.The values stated ineach system may not be exact equivalents;therefore,each1This method is under the jurisdiction ofASTM Committee D13 on Textiles andis the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved Jan.1,2021.Published January 2021.Originallyapproved
14、in 1953.Last previous edition approved in 2012 as D1445 12.DOI:10.1520/D1445_D1445M-12R21.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary
15、page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theD
16、evelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.system shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practice
