1、Designation:D144505 Designation: D1445/D1445M 12Standard 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,
2、in the case 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
3、its introduction 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 poun
4、ds divided bythe 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).psi. Th
5、e U.S. Department of Agriculture obtained results from both instruments onspecimens from the same samples of a large number of cottons. From this study, an empirical equationto express flat bundle test results in psi wasBreaking strength, 1000 psi = (10.81106 3 P.I.) 0.12When it was shown that a fin
6、ite gauge length test was more highly correlated with yarn strengththan tests made at zero gauge length, the clamp design was modified to accommodate a18 inch (3.2mm)in. 3.2 mm spacer. Selection of an engineering unit for reporting of results from18 inch (3.2mm)in. 3.2 mm gauge tests presented a pro
7、blem. However, the use of the tex for linear density andthe introduction of a pendulum type instrument calibrated in kilograms led to the expression of resultsin grams-force per tex (gf/tex).gf/tex. The clamp width without spacer is 11.81 mm and with spaceris 15.00 mm. The bundle of fibers is mounte
8、d across the clamp width and trimmed to the width. Thebundle mass is mg/11.81 mm or mg/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 thete
9、xtile industry. Therefore, the empirical relationship is retained to calculate zero gauge cotton fibertensile strength designated as the Pressley strength in Eq 3 and 4 of D1445.1. Scope1.1 This test method covers the determination of (1) the tensile strength or breaking tenacity of cotton fibers as
10、 a flat bundleusing a nominal zero gauge length, or (2) the tensile strength or breaking tenacity and the elongation at the breaking load of cottonfibers as a flat bundle with18-in. (3.2-mm)3.2-mm clamp spacing. This test method is applicable to loose ginned cotton fibersof untreated cottons whether
11、 taken before processing or obtained from a textile product.1.2 This test method is designed primarily for use with special fiber bundle clamps and special strength testing instruments butmay be used with other tensile strength and elongation testing machines when equipped with appropriate adapters
12、to accommodatethe fiber clamps.NOTE 1Other methods for measuring the breaking tenacity of fiber bundles include Test Method D1294, Test for Breaking Strength of Wool FiberBundles1 in gauge Length;2and D5867, Test Method for Measurement of Physical Properties of Cotton Fibers by High Volume Instrumen
13、ts.1This method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved March 1, 2005.2012. PublishedApril 2005.2012. Originally approved in 1953. Last previous edition approved in 19952005 as D1445
14、 905. DOI:10.1520/D1445-05.10.1520/D1445_D1445M-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This do
15、cument is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions a
16、s appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.3The values stated in either acceptable metric units
17、or in other units shall be regarded separately as standard. The valuesexpressed in each system may not be exact equivalents; therefore, each system must be used independently of each other, withoutcombining values in any way.1.3 The values stated in either SI units or inch-pound units are to be rega
18、rded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the sa
19、fety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to Text
20、ilesD1294 Test Method for Tensile Strength and Breaking Tenacity of Wool Fiber Bundles 1-in. (25.4-mm) Gage LengthD1441 Practice for Sampling Cotton Fibers for TestingD1447 Test Method for Length and Length Uniformity of Cotton Fibers by Photoelectric MeasurementD1776 Practice for Conditioning and T
21、esting TextilesD3025 Practice for Standardizing Cotton Fiber Test Results by Use of Calibration Cotton StandardsD5867 Test Methods for Measurement of Physical Properties of Cotton Fibers by High Volume InstrumentsD7139 Terminology for Cotton Fibers3. Terminology3.1 For all terminology related to D13
22、.11, see Terminology D71393.1.1 The following terms are relevant to this standard: breaking force, breaking tenacity, cotton, elongation at breaking load,tenacity, tensile strength.3.2 For all other terminology related to textiles, refer to Terminology D123.4. Summary of Test Method4.1 A bundle of c
23、otton fibers is combed parallel with the aid of specialized clamps to minimize loose fibers that are in thebundle, secured in clamps, cut to a known length, broken in thea tensile testing machine, and weighed. Tensile strength or breakingtenacity is calculated from the ratio of breaking load to bund
24、le mass (weight).4.2 Elongation at the breaking force may be determined on the specimens tested for breaking strength with18-in.(3.2-mm)3.2-mm clamp spacing. The elongation is normally calculated as a percentage of the nominal gauge length.5. Significance and Use5.1When the level of results in the l
25、aboratory the purchaser and the supplier are both controlled by use of calibration cottons,Test Method D1445 for the determination of the tensile strength and elongation is considered satisfactory for acceptance testingof commercial shipments of cotton and has been used extensively in trade for acce
26、ptance testing.5.1.1DiscussionTenacity is commonly expressed as centinewtons per tex (cN/tex), grams-force per denier (gf/den) orpounds-force per denier (lbf/den). Tenacity in centinewtons/tex is numercially equal to tenacity in grams-force/tex times 0.981.5.1.2In case of a dispute arising from diff
27、erences in reported test results when using Test Method D1445 for acceptance testingof commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical biasbetween their laboratories. Competent statistical assistance is recommended for the
28、investigation of bias. As a minimum, the twoparties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the typein question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The averagere
29、sults from the two laboratories should be compared using Students t-test for unpaired data and an acceptable probability levelchosen by the two parties before the testing is begun. If a bias is found, either its cause must be found and corrected or the purchaserand the supplier must agree to interpr
30、et future test results in the light of the known bias.5.1 This test method is considered satisfactory for acceptance testing when the levels of the laboratories are controlled by theuse of the same reference standard cotton samples because the current estimates of between-laboratory precision are ac
31、ceptableunder these conditions. If there are differences of practical significance between reported test results for two laboratories (or more),comparative tests should be performed to determine if there is a statistical bias between them, using competent statisticalassistance. As a minimum, ensure
32、the test samples to be used are as homogeneous as possible, are drawn from the material fromwhich the disparate test results were obtained, and are randomly assigned in equal numbers to each laboratory for testing. The testfrom the two laboratories should be compared using a statistical test for unp
33、aired data, at a probability level chosen prior to thetesting series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjustedin consideration of the known bias.5.2 This test method is useful in research studies to determine the infl
34、uence of variety, environment, and processing on fiberstrength and elongation; and in studies of the relationships between these fiber properties, processing performance, and quality ofend-product.D1445/D1445M 1225.3 Values obtained for flat bundle tenacity and elongation show a high correlation wit
35、h values measured on single fibers andrequire much less time and skill.5.4 Studies have shown that strength measurements obtained with different types of instruments are highly correlated, but theresults are on different levels.35.5By use of correction factors calculated from tests made on standard
36、calibration samples of known or established test values,the results obtained with different types of instruments at a specified gage length can be adjusted to comparable levels. Due todifferences in cottons, strength test results for one gage length cannot be reliably estimated from tests made at a
37、different gagelength.5.5 By use of correction factors calculated from tests made on standard calibration samples of known or established test values,the results obtained with different types of instruments at a specified gauge length can be adjusted to comparable levels. Due tothe normal variation i
38、n cottons, strength test results for one gauge length cannot be reliably estimated from tests made at a differentgauge length.5.6 The terms tensile strength and breaking tenacity are sometimes used interchangeably. They are relational but are notequivalent (see 12.1.1 and 12.1.2). Tenacity is common
39、ly expressed as centinewtons per tex (cN/tex), grams-force per denier(gf/den) or pounds-force per denier (lbf/den). Tenacity in centinewtons/tex is numerically equal to tenacity in grams-force/tex times0.981.6. Apparatus and Materials6.1 Tensile Testing MachineEither of two commercially available fi
40、ber bundle tensile testing machines, one of the pendulumtype and one of the inclined-plane type, described in Appendix X1, or other machine from which comparable results can beobtained.6.2 Laboratory Balance:6.2.1 Balance, having a capacity of 3 or 5 mg and a sensitivity of 60.01 mg for the zero gau
41、ge length test.6.2.2 Balance, having a capacity of 5 or 10 mg and a sensitivity of 0.01 mg for18-in. (3.2-mm) gage length test. -in. 3.2-mmgauge length test.6.3 Ancillary equipment from the instrument manufacturers.6.3.1 Clamp Vise (Pressley type or Stelometer type), with a device to indicate approx
42、imately 8 lbfin. (9 kgfcm)9 kgfcmtorque.6.3.2 Fiber Clamps, having a total thickness of 0.465 6 0.001 in. (11.8111.81 6 0.02 mm). mm.6.3.3 Spacer, having a thickness of 0.125 6 0.001 in. (3.23.2 6 0.02 mm). mm.6.3.4 Clamp Wrench or Torque Wrench.6.3.5 Coarse Comb, approximately 8 teeth/in. (3 teeth/
43、cm),3 teeth/cm, or Fibrograph comb.6.3.6 Fine Comb, approximately 52 teeth/in. (20 teeth/cm). , approximately 52 teeth/in. 20 teeth/cm.6.3.7 Black Paper, to hold bundles.6.3.8 Shearing Knife.6.3.9 Tweezers.6.3.10 Standard Calibration Cotton, having specified fiber strength.6.3.11 Fiber Clips or Samp
44、le Clips.7. Sampling7.1 Take the lot sample and laboratory samples as directed in Practice D1441.8. Preparation, Calibration, and Verification of Apparatus8.1 Tensile Testing InstrumentTensile testing instrumentBefore making fiber strength tests, check the instrument and clampvise for mechanical adj
45、ustment as directed for the specific instrument in Appendix X1, or in accordance with the manufacturersinstructions.8.2 Laboratory BalanceLaboratory balanceCheck the zero setting of the laboratory balance and make sure its sensitivity iswithin the range to be used.8.3 Clamp LeathersInspect the leath
46、ers in the clamps frequently to ensure that they are in good condition. Keep the inneredges of the leathers trimmed flush with the metal surface and replace the leathers as soon as grooves become evident. ClampleathersInspect the leathers in the clamps frequently to ensure that they are in good cond
47、ition. Keep the inner edges of theleathers trimmed flush with the metal surface and replace the leathers as soon as grooves are observed.8.4 Check Test Use of Standard Calibration Cotton SamplesEach day before making other tests, make a check test of atleast three specimens per technician on one or
48、more standard calibration samples to check the reproducibility and uniformity ofresults. If available, use standard calibration samples with test values within the range of the unknown samples being tested. Make3Burley, Jr., S. T., and Carpenter, F. “Evaluation of Results Obtained on Available Types
49、 of Fiber Strength Testers Using Various Gauge Spacings and Their Relation toYarn Strength,” AMS-71, U. S. Dept. of Agriculture (Sept. 1955).Textile Research Journal (TRJ), Vol 24, 1954, pp. 251-260D1445/D1445M 123additional check tests in a similar manner at least three more times during a working day to obtain results for the calculation ofcorrection factors. The calculated breaking tenacity or tensile strength values of the samples tested during the same time periodcan be adjusted to the standard level by applying the correction f
