1、Designation: D 2591 07Standard Test Method forLinear Density of Elastomeric Yarns (Short LengthSpecimens)1This standard is issued under the fixed designation D 2591; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 lineardensity of short lengths of “as produced” elastomeric yarnsmade fro
3、m rubber, spandex or other elastomers.NOTE 1For the determination of linear density of elastomeric yarnsusing skeins, refer to Test Method D 6717.1.2 This test method is not applicable to covered, wrapped,or core-spun yarns, or yarns spun from elastomeric staple, orelastomeric yarns removed from fab
4、rics.1.3 This test method is applicable to elastomeric yarnshaving a range of 40 to 3200 dtex (36 to 2900 denier).1.4 The values stated in either SI units or U.S. Customaryunits are to be regarded separately as standard. Within the testthe US Customary units are in parentheses. The values stated ine
5、ach system are not exact equivalents; therefore, each systemshall be used independently of the other.1.5 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 and hea
6、lth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 2258 Practice for Sampling Yarn for TestingD 6717 Test Method for Linear Density of ElastomericYarns (Skein Specimens)D 4849 Termin
7、ology Relating to Yarns and Fibers3. Terminology3.1 For all terminology relating to D13.58, Yarns andFibers, refer to Terminology D 4849.3.1.1 The following terms are relevant to this standard:denier, elastomeric yarn, linear density, tex.3.2 For all other terminology related to textiles, refer toTe
8、rminology D 123.4. Summary of Test Method4.1 A pre-relaxed specimen is fastened in verticallymounted apparatus under a specified tension.Aspecified lengthis cut from the specimen and weighed, and the linear densitycalculated.5. Significance and Use5.1 This test method is considered satisfactory for
9、accep-tance testing of commercial shipments because current esti-mates of between-laboratory precision are acceptable and themethod is used extensively in the trade for acceptance testing.5.1.1 If there are differences of practical significance be-tween reported test results for two laboratories (or
10、 more),comparative tests should be performed to determine if there isa statistical bias between them, using competent statisticalassistance. As a minimum, use samples for such comparativetests that are as homogeneous as possible, drawn from the samelot of material as the samples that resulted in dis
11、parate resultsduring initial testing, and randomly assigned in equal numbersto each laboratory. The test results from the laboratoriesinvolved should be compared using a statistical test forunpaired data, at a probability level chosen prior to the testingseries. If bias is found, either its cause mu
12、st be found andcorrected, or future test results for that material must beadjusted in consideration of the known bias.5.2 Linear density of elastomeric yarns is used in somecalculations for tensile and elastic properties.5.3 The test method is based on elastomeric yarns in lthe“as-produced” conditio
13、n, but may be used for treated elasto-meric yarns provided the treatment is specified. The method1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.Current edition approved Jan. 1, 2007. Published J
14、anuary 2007. Originallyapproved in 1967. Discontinued 1979 and reinstated as D 2591 01. Last previousedition approved in 2001 as D 2591 012For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.does not cover the removal of finish for the determination oflinear density of “finish-free” elastomeric yar
16、ns.6. Apparatus36.1 Specimen Boards, with short pile or plush surfaces ofblack or contrasting color, for storing specimens during relax-ation period.6.2 Linear Density Apparatus, mounted vertically on a wallor in a sturdy, stable vertical support and containing theessential parts listed below. See F
17、ig. 1 and Annex A1 forgeneral construction details of suitable apparatus.6.2.1 Steel Plate, about 100 mm (4 in.) wide and 1.3 m (1.4yd) long.6.2.2 Clamps, three toggle-action type with rubber tips.6.2.3 Brass Plates, two, with slots at right angles to be usedfor controlling the alignment and length
18、of the specimen.6.2.3.1 The slots are positioned such that the distancebetween the slot midlines provides a gage length of 1000 mmwhen using the tex system or 900 mm when using the deniersystem. If necessary, the two gage lengths can be obtained byhaving the upper slot assembly adjustable, or by hav
19、ing twoseparate test apparatuses.6.3 Tensioning Weights, with varioius masses from 10 mg to3 g as required, to pretension the specimens to 1.0 6 0.1 cN/tex(0.9 6 0.09 gf/d) tension based on the nominal linear densityof the yarn.6.4 Razor Blades, safety single-edge, or wood-carving typeknife.6.5 Bala
20、nce, with an accuracy of 6 0.1% of the expectedmass of the specimens.3Components are commercially available.NOTE 1Drawing not to scale. For conversion to U.S. customary units,divide mm by 25.4 to obtain inchesFIG. 1 Linear Density ApparatusD25910727. Sampling, Test Specimens, and Test Units7.1 Lot S
21、ample As a lot sample for acceptance testing,take a random number of shipping units directed in anapplicable material specification or other agreement betweenthe purchaser and the supplier, such as an agreement to usePractice D 2258. Consider shipping cases or other shippingunits to be the primary s
22、ampling units.NOTE 2An adequate specification or other agreement between thepurchaser and the supplier requires taking into account the variabilitybetween shipping units, between packages or ends within a shipping unit,and between specimens from a single package to provide a sampling witha meaningfu
23、l producers risk, consumers risk, acceptable quality leveland limiting quality level.7.2 Laboratory Sample As a laboratory sample for accep-tance testing, take at random from each shipping unit in the lotsample the number of packages directed in an applicablematerial specification or other agreement
24、 between the pur-chaser and the supplier, such as an agreement to use PracticeD 2258. Preferably, take the same number of packages fromeach of the shipping units selected. If differing numbers ofpackages are to be taken from the shipping units, determine atrandom which shipping units are to have eac
25、h number ofpackages for testing.7.3 Test Specimens From each package or end in thelaboratory sample, prepare six specimens, as directed in 7.3.1.7.3.1 Remove the outer layer of yarn from the package.Avoid any damaged areas in selecting segments for testing.Carefully unwind yarn from the package with
26、 as low a tensionas possible to avoid stretching. Cut five approximately 1300mm (50 in.) length segments of yarn from the package, takingthem at irregular intervals of at least2m(2yd).7.3.2 Place the specimens without tension on a specimenboard. Allow the segments to relax without stress for at leas
27、t 4h as directed in 9.2.8. Conditioning8.1 Preconditioning is not necessary for currently producedrubber and other elastomeric yarns.8.2 Condition the specimens, without tension, on specimenboards in the standard atmosphere for testing textiles which is21 6 1C(706 2 F) and 65 6 2 % relative humidity
28、 for aminimum of 4 h.9. Procedure9.1 Test all specimens in the standard atmosphere for testingtextiles.9.2 Select a tension weight that will apply 1.0 6 0.1 cN/tex(0.9 6 0.09 gf/d) tension based on the nominal linear densityof the yarn.9.3 Remove the conditioned specimen from the board andfasten one
29、 end in the top clamp of the apparatus. Attach theselected tension weight to the opposite end of the test speci-men.9.4 Carefully lower the specimen and tension weight andallow the specimen to hang freely in the vertical slots of the testapparatus. Do not allow the tension weight to drop suddenly as
30、this will put abnormal tension on the specimen affecting thelength.NOTE 3Release of the weight from the palm of the hand has lesseffect on the tension than releasing the weight from between thumb andfinger.9.5 After approximately 5 s, close the bottom clamp andthen the middle clamp. Cut the specimen
31、 centrally in thebottom slot and then in the top slot, using a straight-onperpendicular cutting action without lateral action. Lateralaction may cause stretching. The actual length of the testspecimen after cutting is 1 m (1000 mm) 6 1mmor0.9m(900 mm) 6 1 mm depending upon the yarn numbering systemu
32、sed.9.6 Weigh the specimen and record its mass to within 0.1 %.9.7 Calculate the linear density as directed in 10.1, thencompare the calculated linear density to the nominal densitygiven and proceed as follows:9.7.1 If the calculated density is within5%ofthegivennominal density, test 4 additional sp
33、ecimens as directed in9.3-9.6, for a total of five.9.7.2 If the calculated density is different from the givennominal density by more than 5 %, discard the result, changethe tension weight to meet 1.0 6 0.1 cN/tex (0.9 6 0.09 gf/d)tension based on the calculated linear density of the yarn. Testa tot
34、al of 5 specimens as directed in 9.3-9.6, under the newlydetermined tension.10. Calculation or Interpretation of Results10.1 Calculate the linear density for each specimen to thenearest 0.1 dtex (0.1 denier), using Eq 1 or Eq 2.Td5 10000 3 M / L (1)D 5 9000 3 M / L (2)where:Td= linear density, dtex,
35、D = linear density, denier,M = mass of specimen, g, andL = length of specimen, m. (For tex system L = 1 mFordenier system L = 0.9 m)10.2 Calculate the average linear density for each laboratorysampling unit and for the lot.10.3 If requested, calculate the coefficient of variation,standard deviation,
36、 or both for each laboratory sampling unitand for the lot.11. Report11.1 State that the samples were tested as directed in TestMethod D 2591. Describe the material or product sampled andthe method of sampling used.11.2 Report the following information:11.2.1 The linear density for each specimen, eac
37、h laboratorysampling unit and the lot,11.2.2 The coefficient of variation, or standard deviation, orboth, if calculated.11.2.3 The pretension used, and11.2.4 Any modification to the method.12. Precision and Bias12.1 An interlaboratory study was performed in 1997 toestimate variability of the test me
38、thod. The study included 2operators in one laboratory. Each operator measured fiveD2591073specimens for five different denier elastomeric yarns on fivedifferent dates. ANOVA was used to determine variancecomponents:12.2 Method repeatability is defined as the “maximumdifference” that can “reasonably”
39、 be expected between two testresults obtained on the same material when the test results areobtained in the same laboratory. Repeatability standard devia-tion, sr, is taken to be the square root of the “specimen”variance component, and represents within-operator precision.Method reproducibility is d
40、efined as the “maximum difference”that can “reasonably” be expected between two test resultsobtained on the same material when the test results areobtained from different laboratories.4sR, the total standarddeviation, is formed by taking the square root of the sum ofintra- and inter-laboratory varia
41、nce components.NOTE 4Because the interlaboratory test included less than the recom-mended five laboratories, estimates of precision data in Table 1 and Table2 may be either underestimated or overestimated to a considerable extentand should be used with special caution.12.3 BiasThe procedure of this
42、test method produces atest value that can be defined only in terms of a test method.There is no independent, referee method by which bias may bedetermined. This test method has no known bias.13. Keywords13.1 elastomeric yarn; linear densityANNEXA1. CONSTRUCTION OF LINEAR DENSITY APPARATUSA1.1 Materi
43、alsA1.1.1 Steel Plate, low carbon (cold-rolled), about 100 mm(4 in.) wide by at least 1300 mm (50 in.) long and about 12.5mm (0.5 in.) thick (for rigidity).A1.1.2 Brass Plates, 2, as wide as the metal plate and atleast 6 mm (0.025 in.) thick. Plates need to be the samethickness. One plate is 75 mm (
44、3 in.) long and the other is 105mm (4 in.) long.A1.1.3 Machine Screws, flathead brass for fastening thecutting blocks and round head or flathead metal to fasten theclamps to the brass plates.A1.1.4 Clamps, three toggle-action type, with rubber tips.Clamps should operate easily without stiffness.A1.1
45、.5 Angle Iron, to join the metal plate and the base plateif a platform is used, or fixtures for mounting the metal plate ona wall.A1.2 Assembly of Apparatus (See Fig. 1.)A1.2.1 Prepare the brass plates in the form shown in Fig. 1.The depth of the slots and the thickness of the sectionscontaining the
46、 slots are critical for controlling the length of thespecimen cut and the vertical alignment of the specimen. Theslots in each plate must be perpendicular to one another and tothe edges of the plate.A1.2.2 Locate and tap holes for machine screws in the brassplates and steel plate such that the cente
47、r line across the cuttingslots are 1000 6 0.5 mm (39.37 in.) apart when the brass platesare fastened in place.A1.2.3 Fasten one clamp above the slotted section of theupper brass plate, one under the slotted section of the upperbrass plate and one under the slotted section of the bottombrass plate. T
48、hen, fasten the brass plates to the metal plate.A1.2.4 Fasten the metal plate to a wall or join it to a heavybase plate with an angle iron at the back.A1.2.5 In the finished apparatus, the following points arecritical:A1.2.5.1 The yarn specimen must hang vertically (plumb)in the vertical slots when
49、fastened in the top clamp.A1.2.5.2 Coarser yarns must be able to move easily in andout of the vertical slots.4John Mandel and Theodore W. Lashof, 1987. The Nature of Repeatability andReproducibility. Jour. Quality Technology, 19 (1).TABLE 1 Linear Density, Average Denier and Components ofVariation Expressed as Squares of the Standard DeviationNOTEResponse = Actual DenierNominal Denier Average Denier Components of VarianceV(Operator) V(Date) V(Specimen)20 20.55060 0.07576 0.17347 0.1920240 40.43160 0 0.25813 1.7033570 71.09280 0 1.83081 1.20301280 281.22480 0 2.91513
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