1、Designation: D7812 16Standard Test Method forTensile Testing of Aramid Paper1This standard is issued under the fixed designation D7812; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthe
2、ses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the tensile testing of aramidpaper with thickness less than 1 mm. This test method includestesting procedures only and includes n
3、o specifications ortolerances.1.2 The procedures given in this test method are for use withcomputer-controlled constant-rate-of-elongation tensile testingequipment.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This sta
4、ndard 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 Documents2.1
5、ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD202 Test Methods for Sampling and Testing UntreatedPaper Used for Electrical InsulationD374M Test Methods for Thickness of Solid ElectricalInsulation (Metric)D1776 Practice for Conditioni
6、ng and Testing TextilesD6477 Terminology Relating to Tire Cord, Bead Wire, HoseReinforcing Wire, and FabricsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3. Terminology3.1 For d
7、efinitions of other terms related to textiles, refer toTerminology D123.3.2 For definitions of terms related to force and deformationin textiles, refer to Terminology D6477.3.3 Definitions:3.3.1 aramid paper, nplanar structures deposited from anaqueous suspension that has a thickness less than 1 mmc
8、ontaining at least 50 mass percent aramid.3.4 The following terms are relevant to this standard:breaking force, elongation, initial modulus, tensile strength,and Tensile Energy Absorption.4. Summary of Test Method4.1 A conditioned sample of aramid paper is clamped in atensile testing machine and the
9、n stretched or loaded untilbroken.4.2 The output of a constant-rate-of-extension (CRE) tensiletesting machine can be connected with electronic recording andcomputing equipment, which may be programmed to calculateand print the test results of tensile properties of interest.4.3 Breaking force and elo
10、ngation are determined directly.Modulus and Tensile Energy Absorption are calculated fromthe force-elongation curve.5. Significance and Use5.1 The levels of tensile properties obtained when testingaramid paper are dependent on the age and history of thespecimen and on the specific conditions used du
11、ring the test.Among these conditions are rate of stretching, type of clamps,gauge length of specimen, temperature and humidity of theatmosphere, rate of airflow across the specimen, and tempera-ture and moisture content of the specimen. Testing conditionsaccordingly are specified precisely to obtain
12、 reproducible testresults on a specific sample.5.2 Tensile strength is used in engineering calculationswhen designing various types of products.5.3 Elongation of the paper is taken into consideration in thedesign and engineering of reinforced products because of itseffect on uniformity of the finish
13、ed product and its dimensionalstability during service.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 Jan. 1, 2016. Published February 2016.
14、DOI: 10.1520/D781216.2For referenced ASTM standards, 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.Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.4 Stiffness is a measure of the resistance of the paper toextension as a force is applied.5.5 Tensile Energy Absorption is dependent on the relation-ship of force to elongation. It is a measure of the ability of atextile str
16、ucture to absorb mechanical energy. Tensile EnergyAbsorption is work-to-break per area.5.6 It should be emphasized that, although the precedingparameters are related to the performance of the product, theactual configuration of the product is significant. Shape, size,and internal construction also c
17、an have appreciable effects onproduct performance. It is not possible, therefore, to evaluatethe performance of the end product in terms of the reinforcingmaterial alone.5.7 If there are differences of practical significance betweenreported test results for two laboratories (or more), compara-tive t
18、ests 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 materialfrom which the disparate test results were obtained, and thatare ra
19、ndomly 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 unpaired data, ata probability level chosen prior to the testing series.
20、 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 ThicknessMicrometer, conforming to the specifica-tions as given in Test Method D374M.6.2 GrammageWeighing device, readable and accurate towithin
21、0.25 % of the applied load. When in use, the weighingdevice shall be shielded from air currents.6.3 Tensile Testing MachineA single-strand tensile testingmachine of the constant rate of extension (CRE) type. Thespecifications and methods of calibration and verification ofthese machines shall conform
22、 to Specification D76. The testingmachine shall be equipped with a data-acquisition system.6.4 ClampsSide action clamps with rubber-coated flat jawfaces. The test specimen shall be held in such a way thatslippage relative to the grips is prevented as much as possible.The width of the jaw faces shoul
23、d be equal to or larger than thesample width. If the clamps are of the air-actuated type, adjustthe air pressure to prevent specimens slipping in the jaws, butkeep the air pressure below the level that will cause specimensto break at the edge of the jaws. If the break is within 5 mm ofthe edge, the
24、result must be discarded.6.5 Specimen Cuttera device capable of cutting specimensfor testing that are uniform in width to within 60.2 mm of thespecified specimen width and with edges parallel to within60.1 mm. A double-blade strip cutter or a laser cutter issatisfactory for this requirement. Other c
25、utting dies may alsobe used, provided they are found to comply with or exceed thetolerances within this standard. Single-blade paper cutters donot comply with the requirements for a specimen cutter forpurposes of this test method.7. Sampling, Test Specimens7.1 For acceptance testing, sample each lot
26、 as directed inTest Methods D202. Take the number of samples for testingspecified for the specific property measurement to be made.7.2 ConditioningBring all specimens to equilibrium in theatmosphere prior to sample cutting as directed in Prac-tice D1776 for Aramids.7.3 PreparationCut the test specim
27、ens from each condi-tioned test unit of the sample. The two options for specimensize are:Type 1: Length 205 6 3 mm; width 15.0 6 0.2 mmType 2: Length 205 6 3 mm; width 25.4 6 0.3 mm7.4 Number of SpecimensAt least five or preferably tenspecimens per sample in machine, and at least five or prefer-ably
28、 ten specimens per sample in the cross-machine direction.8. Conditioning8.1 Bring all specimens to equilibrium in the atmosphereprior to testing as directed in Practice D1776 for Aramids.9. Procedure9.1 Sample PreparationCut the specimens according toSection 7.9.2 ConditioningCondition the samples a
29、s directed in 8.1.9.3 Measurement of ThicknessMeasure the thickness ofthe specimen according to Test Method D374M.9.4 Measurement of Mass Per Unit AreaMeasure thegrams per square meter by weighing the individual specimensas listed in 9.1.9.5 Gauge LengthThe gauge length shall have a totallength for
30、type 1 specimen size of 100 6 1 mm and for type2of1276 1 mm between the jaw faces.9.6 Crosshead Travel RateThe crosshead travel rate is10 % of the nominal gauge length of the specimen. This rate ofcrosshead travel generally results in specimen rupture between10 and 30 s. In cases where rupture consi
31、stently requiresgreater than 30 s, a more rapid rate of crosshead travel must beused, so that specimen rupture occurs between 10 and 30 s.Where a crosshead travel rate other than that stated above isused, the actual crosshead travel rate must be reported.9.7 Slack Start ProcedureClamp one end of the
32、 specimenbetween the jaws of one of the clamps and close it. Place theother end of the specimen through the jaws of the second clampand keep the specimen just slack (zero tension) and close theclamp, taking care that the paper is positioned in the centerlineof the jaws of the clamp. This slack start
33、 procedure has theeffect that the nominal gauge length of the specimen will beslightly greater as specified in 9.5.9.8 Tensile TestingOperate the testing machine at the rateas specified in 9.7 and stretch the specimen until it ruptures.Discard specimens that break in the jaws or within 5 mm of theni
34、p of the jaws. Report the discarded specimen.D7812 16210. Calculation or Interpretation of Results10.1 ThicknessT in mm. Measure the thickness of theindividual specimen conforming to Test Methods D374M.Report results as stated in Section 11.10.2 Mass Per Unit AreaQM in g/m2. Calculate the arealweigh
35、t of the individual specimen by:QM 5ML W106(1)where:QM = mass per unit area, g/m2,M = mass of the specimen, g,L = specimen length, mm, andW = specimen width, mm.Report results as stated in Section 11.10.2.1 Breaking ForceBF in N. When the specimenbreaks, read the breaking force (maximum force) in ne
36、wtons.Report results as stated in Section 11.10.3 Tensile StrengthBT in N/m. Compute the tensilestrength by dividing the breaking force by the specimen widthW:BT 5BFW1000 (2)where:BT = tensile strength, N/m,BF = breaking force, N, andW = specimen width, mm.Report results as stated in Section 11.10.4
37、 Tensile Stress at BreakSB in MPa. Compute thetensile stress by dividing the breaking force by the samplecross-section area:SB 5BFW T(3)where:SB = stress at break, MPa,BF = breaking force, N,W = specimen width, mm, andT = specimen thickness, mm.Report results as stated in Section 11.10.4.1 Tensile I
38、ndexTI in Nm/g. Tensile Index (TI)isthetensile strength scaled on mass per unit area:TI 5BTQM(4)where:BT = tensile strength, N/m, andQM = specimen mass per unit area, g/m2.Report results as stated in Section 11.10.5 Breaking LengthBL in m. Breaking length is thatlength in metres under which the samp
39、le will fail under its ownweight.BL 5BTQMg1000 (5)where:BL = breaking length, m,BT = tensile strength, N/m,QM = specimen mass per unit area, g/m2, andg = constant of gravity, m/s2( 9.8 m/s2).Report results as stated in Section 11.10.5.1 Elongation at BreakEAB in %. Determine theelongation at break o
40、f each conditioned specimen when deter-mined at its breaking force point. With the use of slack start, acorrection of gauge length is required. The procedure fordetermining the slack is as shown in Fig. 1. Take force levelsF1=5%BF and F2=10%BF. Determine the extensions e1and e2 from the extension-fo
41、rce graph at the force levels F1and F2 respectively. Compute the intercept at the extensionaxis using:FIG. 1 Determination of SlackD7812 163L 5e1F2 2 e2F1F2 2 F1(6)where:L = slack, mm,F1 = force 5 % of the breaking force, N,F2 = force 10 % of the breaking force, N,e1 = extension, mm at force F1, and
42、e2 = extension, mm at force F2.10.5.1.1 The equation for elongation at break for the slackstart procedure is given by:EB 5eBF2LL01L 100% (7)where:EB = elongation at break, %,EBF= extension of specimen at the breaking force, mm,L0= gauge length after clamping specimen (absolute dis-tance nip-to-nip b
43、efore movement of crosshead), mm,andL = displacement of crosshead to remove slack (see Fig.1), mm.Report results as stated in Section 11.10.6 StiffnessSTIF in N/m. STIF is the modulus between5 % and 10 % of the breaking force (see Fig. 1).10.6.1 From the displacement point e1 and e2, calculate thest
44、rain s1 and s2 using:s1 5e1 2 LL01Land s2 5e2 2 LL01LSTIF 51000WF2 2 F1s2 2 s1(8)where:STIF = initial stiffness, N/m,L0= gauge length after clamping specimen (absolutedistance nip-to-nip before movement of crosshead),mm,L = displacement of crosshead to remove slack (see Fig.1), mm,F1 = force 5 % of
45、the breaking force, N,F2 = force 10 % of the breaking force, N,e1 = extension, mm at force F1,e2 = extension, mm at force F2,s1 = strain at force F1,s2 = strain at force F2, andW = width of the sample, mm.Report results as stated in Section 11.10.7 Stiffness IndexSTIFI in Nm/g. Stiffness index is th
46、estiffness scaled on mass per unit area:STIFI 5STIFQM(9)where:STIF = stiffness, N/m, andQM = mass per unit area, g/m2.Report results as stated in Section 11.10.8 Tensile Energy AbsorptionTEA in J/m2. The equationused to calculate the Tensile Energy Absorption is:TEA 5106W L01 L!i50n21Fi111Fi2 ei112
47、ei! (10)where:TEA = Tensile Energy Absorption in J/m2,W = sample width, mm,L0= gauge length after clamping specimen (absolute dis-tance nip-to-nip before movement of crosshead), mm,L = displacement of crosshead to remove slack (see Fig.1), mm,FI= force at ith data pair, N,eI= extension at ith data p
48、air, mm,Report results as stated in Section 11.11. Report11.1 State that all specimens were tensile tested as directedin Test Methods D7812. Describe the material or productsampled and the methods of sampling used.11.2 Report the following information:11.2.1 Sample code,11.2.2 Machine or cross-machi
49、ne direction,11.2.3 Test conditions: temperature, humidity, gauge lengthand cross-head speed,11.2.4 Number of specimens tested per sample,11.2.5 Number of specimen failed within 5 mm of the grips,and11.2.6 For the determined parameters: average and standarddeviation of machine and cross-machine result.12. Precision and Bias12.1 PrecisionThe precision of this test method is basedon an interlaboratory study of Test Method D7812, conductedin 2015. Two laboratories tested two different types of aramidpaper (see 12.3), at two sizes
