1、Designation: D7744/D7744M 11Standard Test Methods forTensile Testing of High Performance Polyethylene Tapes1This standard is issued under the fixed designation D7744/D7744M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year
2、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.1. Scope1.1 The test method covers the tensile testing of highperformance polyethylene tapes. The method includes testingproced
3、ure only and includes no specifications or tolerances.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues f
4、rom the two systems may result in non-conformancewith the standard.1.3 This standard includes the following test methods:SectionBreaking Strength (Force) 11Breaking Tenacity 12Breaking Toughness 17Elongation at Break 13Force at Specified Elongation (FASE) 14Linear Density 10Modulus 15Work-to-Break 1
5、61.4 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 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced
6、Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD1907 Test Method for Linear Density of Yarn (YarnNumber) by the Skein MethodD2258 Practice for Sampling Yarn for TestingD4
7、848 Terminology Related to Force, Deformation andRelated Properties of TextilesD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision
8、 of a Test Method3. Terminology3.1 Definitions:3.1.1 high-performance polyethylene, na polyethyleneyarn or tape with a tenacity at break of minimally 1000 mN/tex11 gpd.3.1.2 tape, nin high performance end-uses, a flat, highly-oriented strip of polymer material.3.2 For definitions of terms related to
9、 force and deformationin textiles, refer to Terminology D4848.3.3 The following terms are relevant to this standard:breaking force, breaking strength, breaking tenacity, breakingtoughness, modulus, force-extension curve, force-elongationcurve, elongation, force at specified elongation (FASE), tensil
10、estrength, and work-to-break.3.4 For definitions of other terms related to textiles, refer toTerminology D123.4. Summary of Test Method4.1 A conditioned polyethylene tape is clamped in a con-stant rate of extension tensile testing machine (CRE) and thenstretched or loaded until broken.4.2 Breaking f
11、orce, elongation, and force at specified elon-gation (FASE) are determined directly. Modulus and work-to-break are calculated from the force-elongation curve.5. Significance and Use5.1 The levels of tensile properties obtained when testinghigh performance polyethylene tapes are dependent on the agea
12、nd history of the specimen and on the specific conditions usedduring the test. Among these conditions are rate of stretching,type of clamps, gauge length of specimen, temperature andhumidity of the atmosphere, rate of airflow across the speci-men, and temperature and moisture content of the specimen
13、.1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.19 on Industrial Fibers andMetallic Reinforcements.Current edition approved July 15, 2011. Published September 2011. DOI:10.1520/D7744_D7744M11.2For referenced ASTM stan
14、dards, 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 website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
15、PA 19428-2959, United States.Testing conditions accordingly are specified precisely to obtainreproducible test results on a specific sample.5.2 Breaking strength is used in engineering calculationswhen designing various types of products. When needed tocompare intrinsic strength characteristics tape
16、s of differentsizes or different types of tape, breaking tenacity is very usefulbecause, for a given type of tape, breaking force is approxi-mately proportional to linear density.5.3 Elongation of tape is taken into consideration in thedesign and engineering of reinforced products because of itseffe
17、ct on uniformity of the finished product and its dimensionalstability during service.5.4 The FASE is used to monitor changes in characteristicsof the material during the various stages involved in theprocessing.5.5 Modulus is a measure of the resistance of tape toextension as a force is applied. Alt
18、hough modulus may bedetermined at any specified force, initial modulus is the valuemost commonly used.5.6 Work-to-break is dependent on the relationship of forceto elongation. It is a measure of the ability of a textile structureto absorb mechanical energy. Breaking toughness is work-to-break per un
19、it mass.5.7 Shape, size, and internal construction of the end-productcan have appreciable effect on product performance. It is notpossible, therefore, to evaluate the performance of end productin terms of the reinforcing material alone.5.8 If there are differences of practical significance betweenre
20、ported test results for two laboratories (or more), compara-tive tests should be performed to determine if there is astatistical bias between them, using competent statistical assis-tance. As a minimum, test samples should be used that are ashomogeneous as possible, that are drawn from the materialf
21、rom which the disparate test results were obtained, and thatare randomly assigned in equal numbers to each laboratory fortesting. Other materials with established test values may beused for this purpose. The test results from the two laboratoriesshould be compared using a statistical test for unpair
22、ed data, ata probability level chosen prior to the testing series. If a bias isfound, either its cause must be found and corrected, or futuretest results must be adjusted in consideration of the knownbias.6. Apparatus6.1 Tensile Testing MachineA single-strand tensile testingmachine of the constant r
23、ate of extension (CRE) type. Thespecifications and methods of calibration and verification ofthese machines shall conform to Specification D76. The testingmachine shall be equipped with an autographic recorder(rectilinear coordinates preferred). It is permissible to usetensile testing machines that
24、have a means for calculating anddisplaying the required results without the use of an auto-graphic recorder.6.1.1 ClampsSide action grips with flat jaw faces. Thetest specimen shall be held in such a way that slippage relativeto the grips is prevented insofar as possible. Flat faced gripswere found
25、to fulfill this requirement. The width of the jawfaces should be equal or larger than the sample width. The useof paper has been found to reduce slippage. Air-actuated orhydraulic grips have been found advantageous. In cases wheresamples frequently fail at the edge of the grips, it may beadvantageou
26、s to increase slightly the radius of curvature ofthese edges where the grips come in contact with the test areaof the specimen.6.1.2 The compliance of the total testing system (tensiletester, loadcell and clamping system) shall be less than 0.2 m10-6in. per Newton.6.1.3 Gauge LengthThe gauge length
27、shall be the totallength between the jaw faces.6.1.4 Use a crosshead travel rate in mm/min in./min ofpreferably 50 or 100 % of the nominal gauge length inmillimeters inches of the specimen. The rate used must bereported.7. Sampling7.1 Tape:7.1.1 For acceptance testing, sample each lot as directed in
28、Practice D2258. Take the number of specimens for testingspecified for the specific property measurement to be made.8. Conditioning8.1 Bring all specimens to equilibrium in the atmosphereprior to testing for at least3hasdirected in Practice D1776(UHMW Polyethylene).9. Sample Preparation9.1 The width
29、and the thickness of the samples are deter-mined in accordance with Practice D5947, Option C. Thethickness must be equal or less than 250 m 10-3in. Thewidth of the samples must be in the range of 2 to 150 mm 0.1to 6 in. Due to constraints of the tensile equipment, the testcannot be used for tapes wi
30、der than that limit. If the widthexceeds 150 mm 6 in., the sample must be cut to width so thatit fulfills this requirement.10. Linear Density10.1 ScopeThis test method issued to determine the lineardensity of tape for use in the calculation of tensile propertiessuch as modulus and tenacity.10.2 Numb
31、er of SpecimensFive specimens of 1 m 40 in.length of tape.10.3 ProcedureDetermine linear density form weighingthe five individual tapes as directed in Option 1 of Test MethodD1907 except condition the tape as specified in Section 8.11. Breaking Strength (Force) of Conditioned Tapes11.1 ScopeThis tes
32、t method is used to determine thebreaking strength (force) of tapes after conditioning in theatmosphere for testing (UHMW Polyethylene).11.2 Number of SpecimensTest five specimens.11.3 ProcedureSelect a loading cell and the settings of thetensile tester such that the estimated breaking force of thes
33、pecimen will fall in the range from 10 to 90 % of the full-scaleforce effective at the time of the specimen break. This selectionof the full scale force may be done manually by the operatorbefore the start of the test or by electronic means or computercontrol during the test by automatically adjusti
34、ng the amplifi-cation of the loading cell amplifier.Adjust the distance betweenD7744/D7744M 112the clamps on the testing machine so that the nominal gaugelength of the specimen, measured between the jaws faces of theclamps, is preferably 300 6 2mm126 0.10 in. Make alltests on the conditioned tapes i
35、n the atmosphere for UHMWPolyethylene. Remove the specimen from the sample andhandle it to prevent any change in configuration prior to closingthe jaws of the clamps on the specimen. Avoid any damage tothe tape. Depending on the equipment being used and theavailability of on-line computer control an
36、d data processing,either can be used:Pretension-start procedure (see 11.3.1)orSlack start procedure (see 11.3.2).11.3.1 Slack Start ProcedureThread one end of the speci-men between the jaws of one of the clamps and close it. Placethe other end of the specimen through the jaws of the secondclamp and
37、keep the specimen just slack (zero tension) andclose the clamp, taking care that the tape is positioned in thecenterline of the jaws of the clamp. Operate the testingmachine at the rate as specified in 6.1.3 and stretch thespecimen until it ruptures. When the specimen breaks, read thebreaking force
38、(maximum force) in Newtons pounds-forcefrom the force-elongation curve, from the dial, from thedisplay, or by electronic means. Discard specimens that breakin the jaws or within 10 mm 18 in. of the edge of the jaws. Ifthe clamps are of the air-actuated type, adjust the air pressureto prevent specime
39、ns slipping in the jaws, but keep the airpressure below the level that will cause specimens to break atthe edge of the jaws. This slack start procedure has the effectthat the nominal gauge length of the specimen is not exactly300 mm 12 in. as specified in 10.3, but always will besomewhat more due to
40、 slack in the specimen after closing theclamps.11.3.2 Pretension-Start ProcedureUse a tensioning de-vice that applies a pretension corresponding to 20 6 1 mN/tex0.20 6 0.01 gf/den for high performance PE tapes. Thisdevice may be a weight, a spring, or an air-actuated mecha-nism. Place one end of the
41、 specimen between the jaws of theclamp connected to the loading cell and close it. Place the otherend through the jaw of the second clamp and fix a pretensionweight to the unclamped end or pull the thread such that thespecified pretension in the test specimen is applied. Close thesecond clamp and op
42、erate the testing machine at the ratespecified in 6.1.4. When the specimen breaks (ruptures), readthe breaking force (maximum force) in Newtons pounds-force from the force-extension curve on the chart, from thedial, from the display, or by electronic means. Discard speci-mens that break in the jaws
43、or within 10 mm 38 in. of the nipof the jaws. If the clamps are of the air-actuated type, adjust theair pressure so that specimens will not slip in the jaws, but keepair pressure below the level that will cause specimens to breakat the edge of the jaws.11.4 The velocity of conditioned air flowing ac
44、ross aspecimen while determining tensile properties can have ameasurable effect on the breaking force and elongation at breakbecause of the Gough-Joule effect. The magnitude of this effectdepends on the type of tape, air velocity, and sample history.Interlaboratory testing of nylon, polyester, and r
45、ayon cordsindicates that air velocities of less than 250 mm/s 50 ft/minacross the specimen will not significantly bias the comparisonof cord properties between laboratories.311.5 CalculationCalculate the average breaking forcefrom the observed breaking forces of specimens.11.6 Report:11.6.1 State th
46、at the specimens were tested as directed inSection 10 of Test Methods D7744. Describe the material orproduct sampled and the method of sampling used.11.6.2 Report the option or procedure used; then number ofspecimens tested; and the breaking force for the sample as thebreaking strength.11.7 Precisio
47、n and Bias:11.7.1 See Section 19.12. Breaking Tenacity of Conditioned Tapes12.1 ScopeThis test method is used to determine thebreaking tenacity of polyethylene tapes after conditioning inthe atmosphere for testing UHMW Polyethylene.12.2 CalculationCalculate the breaking tenacity of thesample in term
48、s of milliNewtons per tex (mN/tex) (grams-forceper denier (gf/den) from the breaking strength and the lineardensity using Eq 1 or Eq 2.BTn5BFn 1000LDt(1)BTg5BFl 454LDd(2)where:BTn= breaking tenacity, mN/tex,BTg= breaking tenacity, gf/den,BFn= average breaking force, N,BFl= average breaking force, lb
49、f,LDt= measured linear density, tex, andLDd= measured linear density, denier.12.3 Report:12.3.1 State that the specimens were tested as directed inSection 12 of Test Methods D7744. Describe the material orproduct sampled and the method of sampling used.12.3.2 Report the option or procedure used, the number ofspecimens tested, and the breaking tenacity for the sample.12.4 Precision and Bias:12.4.1 See Section 19.13. Elongation at Break of Conditioned Tapes13.1 ScopeThis test method is used to determine theelongation at break o
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1