1、Designation: D 2524 95 (Reapproved 2003)Standard Test Method forBreaking Tenacity of Wool Fibers, Flat Bundle Method18-in. (3.2-mm) Gage Length1This standard is issued under the fixed designation D 2524; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the break-ing tenacity of wool fibers a
3、s a flat bundle with a18-in.(3.2-mm) clamp separation.1.2 This test method is especially adapted to the fiber bundleclamps and strength testing instruments specified, but may beused on other tensile testing machines when equipped withappropriate adapters to accommodate the prescribed clamps.1.3 This
4、 test method is applicable to wool in any formwhich can be hand-combed into small bundles of parallelizedfibers.NOTE 1Other test methods for measuring breaking tenacity of fiberbundles include Test Methods D 1294, D 1445, and D 540.1.4 This standard does not purport to address all of thesafety conce
5、rns, 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.1.5 The values stated in inch-pound units are to be regardedas the standard. The SI
6、 units in parentheses are provided forinformation only.2. Referenced Documents2.1 ASTM Standards:D 123 Terminology Relating to Textiles2D 540 Testing Man-Made Staple Fibers3D 1294 Test Method for Tensile Strengh and BreakingTenacity of Wool Fiber Bundles1-in. (25.4-mm). GageLength2D 1445 Test Method
7、 for Breaking Strength and Elongationof Cotton Fibers (Flat Bundle Method)2D 1776 Practice for Conditioning Textiles for Testing2D 2525 Practice for Sampling Wool for Moisture23. Terminology3.1 Definitions:3.1.1 breaking tenacity, nthe tenacity corresponding tothe breaking load.3.1.1.1 DiscussionBre
8、aking tenacity is commonly ex-pressed as grams-force per tex (gf/tex), grams-force per denier(gf/den), millinewtons per tex (mN/tex), or millinewtons perdenier (mN/den). Millinewtons are numerically equal to thegrams-force times 9.81.3.1.2 constant-rate-of-extension (CRE) type tensile testingmachine
9、, nin tensile testing, an apparatus in which thepulling clamp moves at a uniform rate, and the force-measuring mechanism moves a negligible distance with in-creasing force, less than 0.13 mm (0.005 in.).3.1.3 constant-rate-of-loading (CRL) type tensile testingmachine, nin tensile testing, an apparat
10、us in which the rate ofincrease of the force is uniform with time after the first3sandthe specimen is free to elongate, this elongation being depen-dent on the extension characteristics of the specimen at anyapplied force.3.1.4 constant-rate-of-traverse (CRT) type tensile testingmachine, nin tensile
11、 testing, an apparatus in which thepulling clamp moves at a uniform rate and the force is appliedthrough the other clamp, which moves appreciably to actuate aforce-measuring mechanism, producing a rate of increase offorce or extension that is usually not constant and is dependenton the extension cha
12、racteristics of the specimen.3.1.5 gage length, nin tensile testing, the length of aspecimen measured between the points of attachment to clampswhile under uniform tension.3.1.6 tenacity, nin a tensile test, the force exerted on thespecimens based on the linear density of the unstrainedspecimen.3.1.
13、6.1 DiscussionIn textiles, tenacity is considered aproperty of fabrics and yarns, and tensile strain is the comple-mentary property of fabrics. In direct yarn numbering systems,tenacity is force divided by linear density. In indirect yarnnumbering systems, tenacity is force times the reciprocal line
14、ardensity.3.1.7 wool, nthe fibrous covering of sheep, Ovis species.1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.13 on Wool and Felt.Current edition approved April 10, 2003. Published August 1995. Originallypublished
15、 as D 2524 66 T. Last previous edition D 2524 94.2Annual Book of ASTM Standards, Vol 07.01.3DiscontinuedSee 1973 Annual Book of ASTM Standards , Part 25.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7.1 DiscussionFor the purpos
16、es of this method, theword wool is used in the generic sense, and includes repro-cessed and reused wool as well as wool as defined in the WoolProducts Labeling Act of 1939: “the fiber from the fleece of thesheep or lamb, or hair of the Angora goat or Cashmere goat(and may include the so called speci
17、alty fibers from the hair ofthe camel, alpaca, llama, and vicuna) which has never beenreclaimed from any woven or felted wool product.”3.1.8 For definitions of other textile terms used in this testmethod, refer to Terminology D 123.4. Summary of Test Method4.1 A bundle of fibers is combed until para
18、llel, placed undera uniform tension sufficient to remove as much crimp aspossible without stretching the fibers, and secured in specialclamps. The fibers are then cut to a known length, broken in thetensile testing machine, removed from the clamps, andweighed. Breaking tenacity is calculated from th
19、e ratio ofbreaking force to bundle linear density. The length measuredunder the applied tension is the basis for computing lineardensity from bundle mass.5. Significance and Uses5.1 Test Method D 2524 for testing wool fibers for tenacityis considered satisfactory for acceptance testing when theparti
20、cipating laboratories, using a reference wool, have shownacceptable between-laboratory precision. It is recommendedthat any program of acceptance testing be preceded by aninterlaboratory check in the laboratory of the purchaser and thelaboratory of the seller on replicate specimens of samples ofthe
21、material to be evaluated. In cases of dispute, the statisticalbias, if any, between the laboratory of the purchaser and theseller should be determined with each comparison being basedon testing randomized specimens from one sample of materialof the type being evaluated.5.2 Values obtained from flat
22、bundle tenacity show a goodcorrelation with values obtained from single fiber tests andrequire much less time.5.3 The basic differences between the procedures describedin Test Method D 2524 and those described in Test MethodD 1294 lie in the manner of clamping the bundles and theshorter gage length
23、employed. The special clamps used in thismethod allow quicker and easier bundle preparation; however,for Test Method D 1294 no special clamps are required. Closeragreement with single fiber tenacity is also obtained with TestMethod D 2524 than when using the procedure in Test MethodD 1294.5.4 As the
24、 observed tenacity of fibers depends in part on thetype of tensile testing machine used and the time required tobreak the specimen, results obtained with the different types ofmachines which may be used in this method will not neces-sarily agree. The machines specifically designed for bundletesting
25、are CRL testers which operate at a loading rate of 1kgf/s and therefore reach the breaking force at variable times inthe order of 5 s. CRE and CRT type machines would beexpected to produce somewhat different results not onlybecause of the inherent difference in operation but becauseCRE and CRT type
26、machines are to be operated at a rate toachieve the breaking load in 20 s.6. Apparatus and Materials6.1 Tensile Testing Machine, having a capacity of at least 7kgf (70 N), equipped to accommodate the specified flat bundleclamps. For CRL testing machines,4the rate of loading isspecified as 1 kgf/s (1
27、0 N/s). For CRE and CRT machines,select a rate of operation which will reach the breaking force inan average time of 20 6 3s.6.1.1 In case the CRE or CRT testing machine is not capableof operating as specified in 6.1, select a rate so as to reach thebreaking force in an average time as close to 20 s
28、 as possibleand report the average time to break.NOTE 2There may be no overall correlation between the resultsobtained with the CRE, CRT or CRL type testing machines. Consequently,these three machines cannot be used interchangeably.6.2 Balance, suitable for weighing 2 to 6 mg with asensitivity of 0.
29、02 mg.6.3 Flat Bundle Clamps and Accessories, including thefollowing components:NOTE 3Pressley clamps and accessories have been found satisfactoryfor this purpose.5Adapters to fit the clamps to various tensile testinginstruments are also available or can be fabricated.6.3.1 Clamps, having a total th
30、ickness of 0.465 6 0.001 in.(11.8 6 0.03 mm) and a 0.125 6 0.001-in. (3.2 6 0.03-mm)spacer.6.3.2 Clamp Vise, with a device to indicate approximately 8lbfin. (0.9 Nm) torque.6.3.3 Clamp Wrench.6.4 Coarse Comb, approximately 8 teeth per in. (3 per 10mm).6.5 Fine Comb, approximately 50 teeth per in. (2
31、0 per 10mm).6.6 Black Paper, to hold bundles.6.7 Shearing Knife or Razor Blade.6.8 Tweezers.6.9 Torque Wrench or Friction Disk Wrench, to indicateapproximately 8 lbfin. (0.9 Nm) torque (optional).6.10 Standard Wool Top Sample6, having an assigned break-ing tenacity of 11.4 gf/tex (112 mN/tex).NOTE 4
32、The standard wool top sample, USDA Lot 58-27, has abreaking tenacity (based on single fiber tests) of 11.4 6 0.6 gf/tex, at the95 % probability level.7. Sampling7.1 Division into LotsTreat a single shipment of a singlefiber type as a lot.7.2 Lot SampleAs a lot sample for acceptance testing,take at r
33、andom the number of shipment containers directed inan applicable material specification or other agreement be-tween the purchaser and the supplier, such as an agreement touse Practice D 2525. Consider shipping containers to be theprimary sampling units.4The Stelometer, manufactured by the Special In
34、struments Laboratory, Inc., 312W. Vine St., Knoxville, TN 37901; and the Clemson Tester (no longer available)have been found satisfactory for this purpose.5Available from J. M. Doebrich and Co., P. O. Box 2789, Tucson, AZ 85702.6Available from the Wool and Mohair Laboratory, Livestock and Seed Divis
35、ion,AMS, U.S. Department of Agriculture, 711 “O” Street, Greeley, CO 80631.D 2524 95 (2003)27.3 Laboratory SampleFor acceptance testing, take alaboratory sample from each shipping container in the lotsample as follows:7.3.1 For loose fiber, grease, and scoured wool, reduce themass of clean fiber sub
36、mitted for testing to approximately 15 gby randomly selecting pieces throughout the mass. Form into aloose sliver by hand.7.3.2 For card sliver and top, cut a length of sliver about 20in. (500 mm) long from each ball submitted for testing.7.3.3 For roving, cut a length about 20 in. (500 mm) longfrom
37、 each spool submitted for testing and include all ends.7.4 Test SpecimensScour or solvent-extract the laboratorysample until residual contamination is 1 % or less of thelaboratory mass, as established by further cleaning of a part ofthe laboratory sample. From each unit in the laboratory sample,prep
38、are five test specimens as directed in 10.1.8. Preparation, Calibration, and Verification ofApparatus8.1 Tensile Testing MachineCheck the calibration of theinstrument according to the manufacturers instruction.8.2 BalanceCheck the zero reading and the sensitivity inthe range to be used.9. Preconditi
39、oning and Conditioning9.1 Bring the laboratory sample to moisture equilibrium fortesting in the standard atmosphere for testing as directed inPractice D 1776.10. Preparation of Specimens10.1 Prepare each specimen by drawing small groups offibers from at least five locations in a unit of the laborato
40、rysample. Parallelize and combine them in a bundle which maybe held conveniently between the thumb and forefinger. De-pending on fiber entanglement, take a sufficient number offibers so that, after combining, an aligned specimen of 2 to 6mg is available for testing.10.2 Grasp the tuft about one-four
41、th the distance from theend of the tuft with the thumb and forefinger or a fiber handvise7and comb the protruding end with the coarse comb toremove loose fibers and foreign material and to secure partialparallelization of the fibers. Reverse the tuft and repeat thecombing on the other end.10.3 Grasp
42、 the partially parallelized tuft at both ends usingthe fingers of one hand, thumb and ring finger holding one endand middle and index fingers holding the other end. Completethe parallelization of the fibers in the tuft by combing with thefine comb; with each pass of the comb release the end of thetu
43、ft toward which the comb is moving and grasp againimmediately after the comb passes the holding position. Toavoid moisture transfer from fingers to fibers, do not handle themiddle section of the tuft. If the specimen is estimated to be tooheavy, remove fibers during the combing operation from either
44、side with the tip of the comb to obtain the correct specimensize. The specimen is now ready to be placed in the clamps.11. Procedure11.1 Test the conditioned specimens in the standard atmo-sphere for testing.11.2 Inspect the leather faces of the clamps frequently toensure that they are in good condi
45、tion. Keep the inner edges ofthe leathers trimmed flush with the metal surfaces and replacethe leathers as soon as grooves become evident to the touch.11.3 Place the parallelized specimen (10.3) in the clamps inthe following manner: Using a Pressley type vise, lock theclamps with a18-in. (3.2-mm) sp
46、acer separating the clamps ofthe vise and open the jaws of the clamps. Hold both ends of thespecimen as directed in 10.3, keeping the specimen approxi-mately14 in. (6 mm) wide, and place it in the central part of theopen clamps. Maintain sufficient tension on the specimen tohold the fibers straight
47、while the jaws of the clamps arelowered and tightened in place by applying an 8 lbfin. (0.9Nm) torque. The torque may be controlled by either avise-mounted, torque-indicating instrument or by a frictiondisk wrench.11.4 Remove the clamps from the vise. Shear off theprotruding ends of the specimen wit
48、h the shearing knife orrazor blade, cutting downward and away from the leather faceof the clamps and flush with the surface.11.5 Insert the loaded clamps in the tensile testing machineand break the test specimen in accordance with the manufac-turers instructions. For other than the special instrumen
49、tsdesigned specifically for flat bundle testing, operate the testinstrument as directed in 6.1.11.6 After the specimen has been broken, record the break-ing force to the nearest scale or chart reading. Remove theclamps from the instrument and place the clamps in the vise.Check to see that all fibers are broken. If all the fibers are notbroken, are broken irregularly indicating some slippage offibers in the clamps, or if the breaking force is less than therequired minimum for the instrument used, discard the speci-men and make a new test. If the brea
