1、Designation:D1445/D1445M12Standard 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 case of revision,t
2、he 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 introduction in1953.The fi
3、rst 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 bundle weight in
4、 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 Agriculture obtained resul
5、ts 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 correlated with
6、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 introduction of a pendulumt
7、ype 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 ormg/15.00 mm.The
8、 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 gauge cotton fiber
9、tensile 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 breaking tenacity and t
10、he 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 primarily for use wi
11、thspecial 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 fiberbundles include Tes
12、t 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 standard.The values sta
13、ted 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 March 1,2012.Published April 2012.Originallyapproved in 1953.Last prev
14、ious edition approved in 2005 as D1445 05.DOI:10.1520/D1445_D1445M-12.2For 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 page onthe ASTM webs
15、ite.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 t
16、hesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1294 Test Method for Tensile Strength and Breaking Te-nacity of Wool Fiber Bundles 1-in.(25.4-mm)GageLengthD1441 Practice for Sampling Cotton Fibers for TestingD1447 Test Method for Length and