1、Designation: D 2612 99 (Reapproved 2005)Standard Test Method forFiber Cohesion in Sliver and Top (Static Tests)1This standard is issued under the fixed designation D 2612; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 describes the measurement of fibercohesion as the force required to cause initial drafting in abund
3、le of fibers in sliver and top. The observed cohesive forcerequired to separate the fibers is converted to cohesive tenacitybased on the linear density of the specimen.NOTE 1For determination of fiber cohesion in dynamic tests, refer toTest Method D 4120.1.2 The values stated in SI units or other un
4、its (in parenthe-ses) are to be regarded separately as standard. The values ineach system are not exact equivalents; therefore, each systemshall be used independently of the other without any combi-nation.1.3 This standard does not purport to address all of thesafety concerns, if any, associated wit
5、h 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:2D76 Specification for Tensile Testing Machines for TextilesD 123 Te
6、rminology Relating to TextilesD 1776 Practice for Conditioning Textiles for TestingD 2258 Practice for Sampling Yarn for TestingD 3333 Practice for Sampling Man-Made Staple Fibers,Sliver, or Tow for TestingD 4120 Test Method for Fiber Cohesion in Roving, Sliver,and Top in Dynamic TestsD 4848 Termino
7、logy for Force and Deformation Propertiesof Textiles3. Terminology3.1 Definitions:3.1.1 fiber cohesion, nthe resistance to separation offibers in contact with one another.3.1.1.1 DiscussionThis resistance is due to the combinedeffects of the surface characteristics, length, crimp, finish, andlinear
8、density of the fibers. Cohesion should not be confusedwith adhesion or sticking together as in a glutinous substance.3.1.2 cohesive force, n in sliver and top testing, the forcerequired to overcome cohesion of a test specimen held in afixed position between two slowly separating clamps.3.1.2.1 Discu
9、ssionIn static tests, cohesive force is mea-sured while a test specimen is held in fixed position betweentwo slowly separating clamps. In dynamic tests, cohesive forceis the force required to maintain drafting in a roving, sliver, ortop.3.1.3 For definitions of other terms related to force anddeform
10、ation in textiles, refer to Terminology D 4848. Fordefinitions of other textile terms used in this test method, referto Terminology D 123.4. Summary of Test Method4.1 The test procedure is based upon the measure of themaximum resisting force when a length of sliver or top ispulled in an axial direct
11、ion. Specified lengths of sliver or topare placed in the clamps of a tensile testing machine and themaximum force developed during separation of the clamps isrecorded. The cohesive tenacity is calculated in terms of theforce per unit linear density of the tested specimen. Thecohesive tenacity is con
12、sidered a measure of the cohesion ofthe fibers in the specimen and is reported in micronewtons/tex(gf/denier).5. Significance and Use5.1 Fiber cohesion is related to the resistance to draftingencountered during textile processing and is affected by such1This test method is under the jurisdiction of
13、ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Yarn Test Methods,General.Current edition approved April 1, 2005. Published July 2005. Originallyapproved in 1967. Last previous edition approved in 1999 as D2612 99.2For referenced ASTM standards, visit the AST
14、M 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 website.TABLE 1 Specimens Required in the Users Laboratory UnderConditions of Unknown Variability Based on Estimat
15、edCoefficients of Variation, % of the AverageFiberAverage Number ofSpecimensBasisACotton 14 n =11.2Man-made 48 n = 21.0Wool 25 n = 15.0BAThe values for n are somewhat larger than will usually be found in practice.BThis value is based on the opinions of knowledgable users.1Copyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.fiber properties as surface lubrication, linear density, surfaceconfiguration, fiber length, and crimp.5.2 Fiber cohesion is affected by the alignment of fiber insliver in addition to the factors listed in 5.1. A
17、half turn of twistin a 140-mm specimen has been found to increase the breakingforce by 30 % and a full turn by 60 %. For this reason, caremust be exercised in precise mounting of specimens.5.3 For the same reason given in 5.2, card sliver gives adifferent breaking tenacity than draw sliver of the sa
18、me fiber.Fibers are more aligned in draw sliver, resulting in lowercohesion.5.4 Increasing the gage length of test specimens reduces thebreaking force and apparent cohesion.5.5 The mathematical relationship between the observedvalue for breaking tenacity and processability has not beenestablished, b
19、ut the observed values can be used in comparingvarious fiber characteristics on a relative basis.5.6 This method for measuring fiber cohesion in sliver ortop (static tests) is not recommended for acceptance testingbecause it is an empirical method which must be followedexplicitly. Results obtained u
20、nder other conditions cannot beexpected to be comparable.5.6.1 In some cases, the purchaser and the supplier mayhave to test a commercial shipment of one or more specificmaterials by the best available method, even though themethod has not been recommended for acceptance testing ofcommercial shipmen
21、ts. In case of dispute arising from differ-ences in reported test results when using this test method foracceptance testing of commercial shipments, the purchaser andsupplier should conduct comparative tests to determine if thereis a statistical bias between their laboratories. Competentstatistical
22、assistance is recommended for the investigation ofbias. As a minimum, the two parties should take a group of testspecimens, which are as homogeneous as possible and whichare from a lot of material of the type in question. Testspecimens then should be randomly assigned in equal numbersto each laborat
23、ory for testing. The average results from the twolaboratories should be compared using appropriate statisticalanalysis and a probability level chosen by the two parties priorto testing. If a bias is found, either its cause must be found andcorrected or the purchaser and the supplier must agree toint
24、erpret future test results with consideration to the knownbias.6. Apparatus and Material6.1 Tensile Testing Machine, a constant-rate-of-specimen-extension (CRE) type, conforming to Specification D76,having adequate response characteristics to properly record theload-elongation curve of the sliver un
25、der test. The capacity ofthe machine must be selected for the maximum force to fallwithin 50 to 90 % of full scale.6.2 Balance, having a capacity of at least 10 g and asensitivity of 0.01 g.6.3 Clamps, preferably pneumatically operated, with facesat least 12.5 mm (0.5 in.) wider than the test specim
26、en, in thedimension perpendicular to the direction of load application,and at least 25 mm (1.0 in.) in the dimension parallel to thedirection of load application.6.4 Mounting TemplateA sheet of paper approximately215 by 280 mm (8.5 by 11 in.), or a longer length when thespecimen length exceeds 280 m
27、m with a 75-mm (3.0 in.)diameter hole cut in the center is used as a mounting board.Two gage reference lines, separated by a distance equal to thedesired specimen length, are drawn across the short dimensionof the paper. The hole is centered between the two referencegage lines.6.5 Tape, cellophane a
28、dhesive or masking type, 13-mm(0.5-in.) wide.7. Sampling7.1 Lot SamplingAs a lot sample for acceptance testing,take at random the number of shipping containers directed inthe applicable material specification or other agreement be-tween the purchaser and supplier, such as an agreement to usePractice
29、 D 3333 or Practice D 2258. Consider shipping con-tainers to be the primary sampling units.NOTE 2An adequate specification or other agreement between thepurchaser or supplier requires taking into account the variability betweenshipping units, between packages, ends or other laboratory sampling unitw
30、ithin a shipping unit if applicable, and within specimens from a singlepackage, end or other laboratory sampling unit to provide a sampling planwith a meaningful producers risk, consumers risk, acceptable qualitylevel, and limiting quantity level.7.2 Laboratory SampleAs a laboratory sample for accep
31、-tance testing, take at random from each shipping container inthe lot sample the number of laboratory sampling units asdirected in an applicable material specification or other agree-ment between purchaser and supplier such as an agreement touse Practice D 3333 or Practice D 2258. Preferably, the sa
32、menumber of laboratory sampling units are taken from eachshipping container in the lot sample. If differing numbers oflaboratory sampling units are to be taken from shippingcontainers in the lot sample, determine at random whichshipping containers are to have each number of laboratory unitsdrawn.7.2
33、.1 Each laboratory sampling unit should be at least 100 m(100 yd) long.7.3 Test SpecimensFrom each laboratory sampling unit,take one specimen. If the standard deviation determined for thelaboratory sample is more than a value agreed upon betweenthe purchaser and supplier, continue testing one specim
34、en fromeach unit in the laboratory sample until the standard deviationfor all specimens tested is not more than the agreed to value or,by agreement, stop testing after a specified number.8. Preparation of Test Specimens8.1 Take the test specimens at random from the laboratorysample to be tested. Tak
35、e care that the specimen is neitherstretched nor distorted.8.2 For slivers produced on a short-fiber processing system,such as the cotton system, take specimens having a lengthequal to the nominal staple length plus 4.0 in. (100 mm). Fortop produced on a long-fiber system of processing, such as thew
36、orsted system, take specimens having a length equal to thefiber length determined from a fiber sorting, plus 4.0 in. (100mm).D 2612 99 (2005)28.2.1 Use the staple length determined by a classer using thehand-stapling technique in the case of cotton, or assigned bythe fiber producer to man-made fiber
37、s developed for processingon the cotton system. For wool or man-made fibers with greatvariability in their length distribution and developed forprocess on a long-fiber system, use the fiber length which islonger than 95 % of the fibers in the specimen.8.3 Place the test specimen (sliver or top), app
38、roximately 12in. (300 mm) in length or longer when necessary, on the papermount described in 6.4, parallel to the longer dimension of thepaper mount and across the center of the 3.0-in. (approximately75-mm) diameter hole.8.4 Fasten the test specimen to the paper mount with stripsof adhesive cellopha
39、ne tape, placed so that the edges of thestrips nearer the hole are aligned with the two marks designat-ing the desired specimen length. Fasten the test specimen to thepaper mount with as little slack as possible; however, take careto avoid distortion or stretching of specimen. Also, mount thetest sp
40、ecimen with no twist in the sliver. By noting thestriations in the sliver produced by the card or draw frametrumpet, the specimen can be rotated and placed on themounting template without twist.9. Conditioning9.1 Precondition as directed in Practice D 1776. Bring thespecimen to moisture equilibrium
41、in the standard atmospherefor testing textiles, which is 70 6 2F (21 6 1C) and 65 62 % relative humidity. Assume that moisture equilibrium isreached when two successive weighings made at least 2 h apartdiffer no more than 0.5 % in weight.10. Procedure10.1 Test adequately conditioned specimens in the
42、 standardatmosphere for testing textiles.10.2 Set the crosshead gage length of the textile testingmachine 0.5 in. (12.7 mm) shorter than the test specimenlength (see 8.2) to allow the test specimen to be placed in theclamps with enough slack to prevent stretching. Adjust the rateof crosshead travel
43、of the testing machine to 10 in. (254mm)/min. Adjust the rate of chart travel so that the load-extension curve utilizes a distance of at least 2.0 in. (50 mm)along the extension axis of the chart.10.3 Place the test specimen in the clamps of the testingmachine in such a manner that the innermost edg
44、e of one of theadhesive strips holding the test specimen to the paper mount isaligned with the bottom edge of the top clamp. Align theinnermost edge of the second adhesive strip with the top edgeof the bottom clamp. With a pair of shears, cut across the8.5-in. (215-mm) dimension of the paper mount o
45、n a line withthe center of the hole so that the paper mount is completelysevered, leaving only the test specimen subject to load appli-cation. Operate the machine to make a load-extension curve ofthe test specimen. From this curve read the cohesive force tothe nearest 0.1 gf from the maximum point o
46、f the curve alongthe load axis of the chart.10.4 Remove the broken portions of the test specimen fromthe clamps. Sever each portion along the innermost edges ofthe adhesive strips and weigh both portions, recording theweight to the nearest 0.01 g.11. Calculation11.1 Calculate the drafting tenacity o
47、f individual specimensin milligrams-force per tex (Note 3) using Eq 1 as follows:DT 5 F 3 L/1000 M (1)where:DT = drafting tenacity, mgf/tex,F = cohesive force, gf,L = specimen length, mm, andM = specimen mass, g.NOTE 3To calculate breaking tenacity in micronewtons per tex(N/tex), multiply milligrams
48、-force per tex (mgf/tex) by 9.81.11.2 Calculate the average cohesive force of all specimensto the nearest 1 mgf/tex.11.3 If requested, calculate the standard deviation or coef-ficient of variation, or both, for each set of test specimens.12. Report12.1 State that the specimens were tested as directe
49、d inASTM Test Method D 2612. Describe the material(s) orproduct(s) sampled and the method of sampling used. Includefiber type, staple length, nominal linear density of the fibers inthe sliver or top, crimp of the fibers (if known), and type ofsliver (card or draw).12.2 Report the following information:12.2.1 Number of specimens tested,12.2.2 The cohesive force and the drafting tenacity for eachlaboratory sampling unit and for the lot, and12.2.3 Coefficient of variation for each set of test speci-mens, if calculated.12.2.4 Any modification to the test.13. Precision an
