1、Designation: D1708 13D1708 18Standard Test Method forTensile Properties of Plastics by Use of MicrotensileSpecimens1This standard is issued under the fixed designation D1708; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This test method covers cer
3、tain material specifications for which a history of data has been obtained using the standardmicrotensile specimen. In general, this test method is superseded for general use by either Test MethodsMethod D882 or TestMethod D638. The very small Type V specimen in Test Method D638 is the recommended s
4、pecimen when limited amounts ofmaterial are available.1.2 This test method covers the determination of the comparative tensile strength and elongation properties of plastics in theform of standard microtensile test specimens when tested under defined conditions of pretreatment, temperature, humidity
5、, andtesting machine speed. This method is applicable when using specimens of any thickness up to 3.2 mm (18 in.), including thinfilms.1.3 This test method cannot be used for the determination of modulus of elasticity. For the determination of modulus, see TestMethod D638 or Test Methods D882.1.4 Te
6、st data Data obtained by this test method are relevant and appropriate for use in engineering design.NOTE 1Tensile properties provide useful data for plastics engineering design purposes. However, because of the high degree of sensitivity exhibitedby many plastics to rate of straining and environmen
7、tal conditions, data obtained by this test method cannot be considered valid for applications involvingload-time scales or environments widely different from those of this test method. In cases of such dissimilarity, no reliable estimation of the limit ofusefulness can be made for most plastics. Thi
8、s sensitivity to rate of straining and environment necessitates testing over a broad load-time scale (includingimpact and creep) and range of environmental conditions if tensile properties are to suffice for engineering design purposes.1.5 The values stated in SI units are to be regarded as standard
9、. The values given in parentheses are for information only.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices
10、 and determine theapplicability of regulatory limitations prior to use.NOTE 2There is no known ISO equivalent to this standard.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the De
11、velopment of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD882 Tes
12、t Method for Tensile Properties of Thin Plastic SheetingD883 Terminology Relating to PlasticsD4000 Classification System for Specifying Plastic MaterialsD5947 Test Methods for Physical Dimensions of Solid Plastics Specimens1 This test method is under the jurisdiction of ASTM Committee D20 on Plastic
13、s and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved Sept. 1, 2013Oct. 1, 2018. Published September 2013October 2018. Originally approved in 1959. Last previous edition approved in 20102013as D1708 - 10.D1708 - 13. DOI: 10.1520/D1708-13.10.1520/
14、D1708-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intende
15、d 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 as appropriate. In all cases only the current
16、versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D6988 Guide for Determination of Th
17、ickness of Plastic Film Test SpecimensE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE2935 Practice for Conducting Equivalence Testing in Laboratory Applications3. Terminology3.1 DefinitionsDefinitions of terms applying to this test method appear in
18、Terminology D883 and Test Method D638, AnnexA2.4. Significance and Use4.1 This test method provides data for quality control and acceptance or rejection under specifications.4.2 Before proceeding with this test method, reference should be made to the ASTM specification of the material being tested.A
19、ny test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof, covered in the materialsspecification shall take takes precedence over those mentioned in this test method. If there are no material specifications, then thedefault conditions herein apply. Table 1
20、Table 1 of Classification System D4000 lists the ASTM materials standards that currentlyexist.5. Apparatus5.1 The apparatus shall be as specified in Test Method D638, with the following exceptions:5.1.1 GripsUse serrated grips faces with care, since yielding or tearing at the grips may interfere wit
21、h measurement ofelongation even when the specimen breaks in the reduced section. Grips with rubber coated faces are recommended for thinspecimens. Self-tightening grips that move as they tighten and result in a change in the grip separation between upper and lowergrips are not satisfactory for this
22、test method. If the specimen tab is not long enough to prevent the grip faces from cocking, useshims to provide more uniform clamping.5.1.2 Drive MechanismThe Regulate the velocity of the drive mechanism shall be regulated as specified in Section 8.5.1.3 The Construct the fixed and movable members,
23、drive mechanism, and grips shall be constructed of such materials and insuch proportions that, after grip slack is taken up, the total elastic longitudinal deformation of the system constituted by these partsdoes not exceed 1 % of the total longitudinal deformation between the grips at any time duri
24、ng the test. If this is not possible,appropriate corrections shall be made in the calculation of strain values.5.1.4 Extension IndicatorThe Use an extension indicator shall be capable of determining the distance between grips at anytime during the test.The instrument shall be test, essentially free
25、of inertia lag at the specified speed of testing, and shall be accurateto 61 % of extension or better.NOTE 3It is desirable that the load indicator and the extension indicator be combined into one instrument, which automatically records the load asa function of the extension or as a function of time
26、. In the latter case, the conversion to a load-extension record can readily be made because extensionis proportional to time after the take-up of the initial grip slack.5.1.5 MicrometersApparatus Use apparatus for measuring the width and thickness of the test specimen shall complythatcomplies with t
27、he requirements of Test Method D5947 and shall read to 0.0025 mm (0.0001 in.) or less. Measure film thicknessin accordance with Guide D6988.6. Test Specimens6.1 Microtensile Use microtensile test specimens shallthat conform to the dimensions shown in Fig. 1. This specimen shall beprepared Prepare sp
28、ecimens by injection molding, compression molding, die-cutting or machining from sheet, plate, slab, orfinished article. Dimensions of a die suitable for preparing die-cut specimens are also shown in Fig. 1. Specimens may also beprepared by injection molding or compression molding.TABLE 1 Tensile St
29、rengthStress at Break for Seven Laboratoriesand Two Materials, MPaMaterialTestSpeed,mm/minAverage SrA SRB rC RDPolyamide(imide) 1.3 193.6 1.60 5.48 4.48 15.3Polybutylene 12.7 31.3 0.80 2.75 9.12 9.12ASr is the within-laboratory standard deviation for the indicated material. It isobtained by pooling
30、the within-laboratory standard deviations of the test resultsfrom all of the participating laboratories:Sr5ffsS1d21sS2d211sSnd2g/ng1/2. (1)BSR is the between-laboratories reproducibility, expressed as a standard deviation,for the indicated material.Cr is the within-laboratory repeatability limit, r
31、= 2.8 Sr.DR is the between-laboratory reproducibility limit, R = 2.8 SR.D1708 1826.2 All surfaces of the specimen shall are to be free of visible flaws, scratches, or imperfections. Marks Carefully remove marksleft by coarse machining operations shall be carefully removed with a fine file or abrasiv
32、e, andabrasive. Smooth the filed surfacesshall then be smoothed with abrasive paper (No. 00 or finer). The Make the finishing sanding strokes shall be made in the directionparallel to the long axis of the test specimen.NOTE 4Tabs shown in Fig. 1 are minimum size for adequate gripping. Shims may be r
33、equired with thicker specimens to keep grips from cocking.Handling is facilitated and gripping improved by the use of larger tabs wherever possible.NOTE 1All dimensions are in millimetres.FIG. 1 Microtensile Die and Test SpecimenD1708 1837. Number of Test Specimens7.1 At least five test specimens sh
34、all be tested for each sample in the case of isotropic materials.For isotropic materials, test atleast five specimens for each sample.7.2 Ten test When testing anisotropic materials, test ten specimens, five normal to and five parallel to the principal axis ofanisotropy, shall be tested for each sam
35、ple in the case of anisotropic materials.anisotropy.7.3 Results Disregard results obtained on test specimens that break at some obvious fortuitous flaw or at the edge of the gripsshall be discarded and retests made, unless grips. Unless such flaws constitute a variable, the effect of which it is des
36、ired to study.bestudied, retest using fresh specimens.8. Speed of Testing8.1 Speed of testing is the velocity of separation of the two members (or grips) of the testing machine when running idle (underno load).8.2 The speed of testing shall be chosen such that the rate of straining shall be approxim
37、ately the same as the rate of strainingobtained when the material is tested at the designated speed according to Test Method D638. Speeds giving rates of strainingapproximating those given in Test Method D638 are as follows:Speed A 0.25 mm (0.01 in.)/minSpeed B 1 to 1.3 mm (0.04 to 0.05 in.)/minSpee
38、d C 10 to 13 mm (0.4 to 0.5 in.)/minSpeed D 100 to 130 mm (4 to 5 in.)/minThese speeds are 0.20 to 0.25 times the speeds designated inTest Method D638, since the effective gauge length of bars specifiedin the latter test method is four to five times that of the microtensile test specimens. When the
39、speed of testing is not specified,Speed B shall be used.use Speed B.9. Conditioning9.1 ConditioningCondition the test specimens in accordance with Procedure A of Practice D618, unless otherwise specifiedby contract or the relevantASTM material specification. Temperature and humidity tolerances shall
40、 be in accordance with Section7 of Practice D618 unless specified differently by contract or material specification.9.2 Test ConditionsConduct the tests at the same temperature and humidity used for conditioning with tolerances inaccordance with Section 7 of Practice D618 unless otherwise specified
41、by contract or the relevant ASTM material specification.10. Procedure10.1 Test specimens shall be tested Perform the tests at the standard laboratory atmosphere as defined in Practice D618, unlessotherwise specified.10.2 Measure and record the minimum value of the cross-sectional area of each specim
42、en. Measure the width to the nearest0.025 mm (0.001 in.) and the thickness to the nearest 0.0025 mm (0.0001 in.) for specimens less than 2.5 mm (0.1 in.) thick, orto the nearest 0.025 mm (0.001 in.) for specimens 2.5 mm (0.1 in.) or greater in thickness.10.3 Set the testing machine so that the dista
43、nce between the upper and lower (or opposing) grips is 22.00 6 0.05 mm (0.86660.002 in.), unless otherwise directed by the pertinentASTM material specification. This distance shall be measured Measure thisdistance with the grips in the closed position.NOTE 5This is easily checked by the use of a 22.
44、00-mm (0.866-in.) gauge block or a pair of inside calipers.10.4 Place the specimen in the grips of the testing machine with the inside edge of each tab visible at the edge of the grip. Toensure uniform axial tensile stress within the gauge length, align the axis of the test specimen shall coincide s
45、o that it coincideswith the center line of the grips of the test machine. Tighten the grips evenly and firmly to the degree necessary to prevent slippageof the specimen during the test, but not to the point where the specimen would be crushed.10.5 Set the speed control at the speed desired (8.2) and
46、 start the machine.10.6 Record the load (or stress) at the yield point (if one exists), the maximum load (or stress) carried by the specimen duringthe test, the load (or stress) at rupture, and the elongation (extension between grips) at the moment of rupture.11. Calculation11.1 Yield Strength,Stres
47、s, Tensile Strength, and Tensile StrengthStress at BreakCalculate the yield strength,stress, tensilestrength, and tensile strengthstress at break in accordance with Test Method D638.11.2 Percentage Elongation at BreakCalculate the percentage elongation at break by dividing the elongation (extension)
48、 atthe moment of rupture of the specimen by the original distance between the grips, and multiplying by one hundred. Report thepercentage elongation to two significant figures.D1708 18411.3 Percentage Elongation at the Yield PointCalculate the percentage elongation at the yield point, if desired, by
49、 dividingthe elongation (extension) at the yield point by the original distance between the grips, and multiplying by one hundred. Reportthe percentage elongation to two significant figures.11.4 Calculate the “average value” and standard deviation for each property in accordance with Test Method D638.12. Report12.1 Results Do not report results of this test method shall not be reported as having been obtained in accordance with TestMethods D882 or Test Method D638 regardless of any modifications that might be made to simulate those testing parameters.12.2 R
