1、Designation: D1708 10Standard 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 of last
2、 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 Department of Defense.1. Scope*1.1 This test method covers certain material
3、 specificationsfor which a history of data has been obtained using the standardmicrotensile specimen. The specimen geometry has beenchanged to be equivalent to that of ISO 12086-2:1995.Ingeneral, this test method is superseded for general use by eitherTest Methods D882 or Test Method D638. The very
4、small TypeV specimen in Test Method D638 is the recommended speci-men when limited amounts of material are available.1.2 This test method covers the determination of the com-parative tensile strength and elongation properties of plastics inthe form of standard microtensile test specimens when tested
5、under defined conditions of pretreatment, temperature, humid-ity, and testing machine speed. It can be used for specimens ofany thickness up to 3.2 mm (18 in.), including thin films.1.3 This test method cannot be used for the determination ofmodulus of elasticity. For the determination of modulus, s
6、eeTest Method D638 or Test Methods D882.1.4 Test data obtained by this test method are relevant andappropriate for use in engineering design.1.5 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to
7、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.NOTE 1There is no known ISO equivalent to this standa
8、rd.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD882 Test Method for Tensile Properties of Thin PlasticSheetingD883 Terminology Relating to PlasticsD4000 Classification System for Specifying Plastic M
9、ateri-alsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 12086-2:1995 PlasticsFluoropolymer Dispersion,Moulding, and Extrusion MaterialsPart 2 Preparation ofTest Specimens and Determination of Properties33. Terminology3.1 Definitio
10、ns: Definitions of terms applying to this testmethod appear in Terminology D883 and Test Method D638,Annex A2.4. Significance and Use4.1 This test method provides data for quality control andacceptance or rejection under specifications.4.2 Before proceeding with this test method, referenceshould be
11、made to the ASTM specification of the materialbeing tested. Any test specimen preparation, conditioning,dimensions, or testing parameters, or combination thereof,covered in the materials specification shall take precedenceover those mentioned in this test method. If there are nomaterial specificatio
12、ns, then the default conditions hereinapply. Table 1 of Classification System D4000 lists the ASTMmaterials standards that currently exist.5. Apparatus5.1 The apparatus shall be as specified in Test MethodD638, with the following exceptions:5.1.1 GripsSerrated grips faces should be used with care,si
13、nce yielding or tearing at the grips may interfere withmeasurement of elongation even when the specimen breaks inthe reduced section. Grips with rubber coated faces arerecommended for thin specimens. Care should be taken when1This test method is under the jurisdiction of ASTM Committee D20 on Plasti
14、csand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved April 1, 2010. Published April 2010. Originallyapproved in 1959. Last previous edition approved in 2006 as D1708 - 06a. DOI:10.1520/D1708-10.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http
16、:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.selecting and using self tightening grips. Those which move asthey tighten and result in a change in the
17、 grip separationbetween upper and lower grips are not satisfactory for this testmethod. If the specimen tab is not long enough to prevent thegrip faces from cocking, shims should be inserted to providemore uniform clamping.5.1.2 Drive MechanismThe velocity of the drive mecha-nism shall be regulated
18、as specified in Section 8.5.1.3 The fixed and movable members, drive mechanism,and grips should be constructed of such materials and in suchproportions that, after grip slack is taken up, the total elasticlongitudinal deformation of the system constituted by theseparts does not exceed 1 % of the tot
19、al longitudinal deformationbetween the grips at any time during the test. If this is notpossible, appropriate corrections shall be made in the calcula-tion of strain values.5.1.4 Extension IndicatorThe extension indicator shall becapable of determining the distance between grips at any timeduring th
20、e test. The instrument shall be essentially free ofinertia lag at the specified speed of testing, and shall beaccurate to 61 % of extension or better.NOTE 2It is desirable that the load indicator and the extensionindicator be combined into one instrument, which automatically recordsthe load as a fun
21、ction of the extension or as a function of time. In the lattercase, the conversion to a load-extension record can readily be madebecause extension is proportional to time after the take-up of the initialgrip slack.5.1.5 MicrometersMicrometers shall read to 0.0025 mm(0.0001 in.) or less.6. Test Speci
22、mens6.1 Microtensile test specimens shall conform to the dimen-sions shown in Fig. 1. This specimen shall be prepared bydie-cutting or machining from sheet, plate, slab, or finishedarticle. Dimensions of a die suitable for preparing die-cutspecimens are also shown in Fig. 1. Specimens may also bepre
23、pared by injection molding or compression molding.6.2 All surfaces of the specimen shall be free of visibleflaws, scratches, or imperfections. Marks left by coarse ma-chining operations shall be carefully removed with a fine file orabrasive, and the filed surfaces shall then be smoothed withabrasive
24、 paper (No. 00 or finer). The finishing sanding strokesshall be made in the direction parallel to the long axis of thetest specimen.NOTE 3Tabs shown in Fig. 1 are minimum size for adequate gripping.Shims may be required with thicker specimens to keep grips fromcocking. Handling is facilitated and gr
25、ipping improved by the use of largertabs wherever possible.7. Number of Test Specimens7.1 At least five test specimens shall be tested for eachsample in the case of isotropic materials.7.2 Ten test specimens, five normal to and five parallel tothe principal axis of anisotropy, shall be tested for ea
26、ch samplein the case of anisotropic materials.7.3 Results obtained on test specimens that break at someobvious fortuitous flaw or at the edge of the grips shall bediscarded and retests made, unless such flaws constitute avariable, the effect of which it is desired to study.8. Speed of Testing8.1 Spe
27、ed of testing is the velocity of separation of the twomembers (or grips) of the testing machine when running idle(under no load).8.2 The speed of testing shall be chosen such that the rate ofstraining shall be approximately the same as the rate ofstraining obtained when the material is tested at the
28、 designatedspeed according to Test Method D638. Speeds giving rates ofstraining approximating those given in Test Method D638 areas follows:Speed A 0.25 mm (0.01 in.)/minSpeed B 1 to 1.3 mm (0.04 to 0.05 in.)/minSpeed C 10 to 13 mm (0.4 to 0.5 in.)/minSpeed D 100 to 130 mm (4 to 5 in.)/minThese spee
29、ds are 0.20 to 0.25 times the speeds designated inTest Method D638, since the effective gauge length of barsspecified in the latter test method is four to five times that of themicrotensile test specimens. When the speed of testing is notspecified, Speed B shall be used.9. Conditioning9.1 Conditioni
30、ngCondition the test specimens in accor-dance with Procedure A of Practice D618, unless otherwisespecified by contract or the relevant ASTM material specifica-tion. Temperature and humidity tolerances shall be in accor-dance with Section 7 of Practice D618 unless specifieddifferently by contract or
31、material specification.9.2 Test ConditionsConduct the tests at the same tempera-ture and humidity used for conditioning with tolerances inaccordance with Section 7 of Practice D618 unless otherwisespecified by contract or the relevant ASTM material specifica-tion.10. Procedure10.1 Test specimens sha
32、ll be tested at the standard labora-tory atmosphere as defined in Practice D618, unless otherwisespecified.10.2 Measure and record the minimum value of the cross-sectional area of each specimen. Measure the width to thenearest 0.025 mm (0.001 in.) and the thickness to the nearest0.0025 mm (0.0001 in
33、.) for specimens less than 2.5 mm (0.1in.) thick, or to the nearest 0.025 mm (0.001 in.) for specimens2.5 mm (0.1 in.) or greater in thickness.10.3 Set the testing machine so that the distance between theupper and lower (or opposing) grips is 22.00 6 0.05 mmTABLE 1 Tensile Strength at Break for Seve
34、n Laboratories andTwo Materials, MPaMaterialTestSpeed,mm/minAverage SrASRBrCRDPolyamide(imide) 1.3 193.6 1.60 5.48 4.48 15.3Polybutylene 12.7 31.3 0.80 2.75 9.12 9.12ASris the within-laboratory standard deviation for the indicated material. It isobtained by pooling the within-laboratory standard dev
35、iations of the test resultsfrom all of the participating laboratories:Sr5 S1!21 S2!21 . 1 Sn!2#/n1/2.(1)BSRis the between-laboratories reproducibility, expressed as a standarddeviation, for the indicated material.Cr is the within-laboratory repeatability limit, r =2.83 Sr.DR is the between-laborator
36、y reproducibility limit, R =2.83 SR.D1708 102(0.866 6 0.002 in.), unless otherwise directed by the pertinentASTM material specification. This distance shall be measuredwith the grips in the closed position.NOTE 4This may easily be checked by the use of a 22.00-mm(0.886-in.) gauge block or a pair of
37、inside calipers.10.4 Place the specimen in the grips of the testing machinewith the inside edge of each tab visible at the edge of the grip.To ensure uniform axial tensile stress within the gauge length,the axis of the test specimen should coincide with the centerline of the grips of the test machin
38、e. Tighten the grips evenlyNOTE 1All dimensions are in millimetres.FIG. 1 Microtensile Die and Test SpecimenD1708 103and firmly to the degree necessary to prevent slippage of thespecimen during the test, but not to the point where thespecimen would be crushed.10.5 Set the speed control at the speed
39、desired (8.2) and startthe machine.10.6 Record the load at the yield point (if one exists), themaximum load carried by the specimen during the test, the loadat rupture, and the elongation (extension between grips) at themoment of rupture.11. Calculation11.1 Yield Strength, Tensile Strength, and Tens
40、ile Strength atBreakCalculate the yield strength, tensile strength, andtensile strength at break in accordance with Test Method D638.11.2 Percentage Elongation at BreakCalculate the per-centage elongation at break by dividing the elongation (exten-sion) at the moment of rupture of the specimen by th
41、e originaldistance between the grips, and multiplying by one hundred.Report the percentage elongation to two significant figures.11.3 Percentage Elongation at the Yield PointCalculatethe percentage elongation at the yield point, if desired, bydividing the elongation (extension) at the yield point by
42、 theoriginal distance between the grips, and multiplying by onehundred. Report the percentage elongation to two significantfigures.11.4 Calculate the “average value” and standard deviationfor each property in accordance with Test Method D638.12. Report12.1 Results of this test method shall not be re
43、ported ashaving been obtained in accordance with Test Methods D882or Test Method D638 regardless of any modifications thatmight be made to simulate those testing parameters.12.2 Report the following information:12.2.1 Complete identification of the material tested, includ-ing type, source, manufactu
44、rers code numbers, form, principaldimensions, previous history, and other pertinent information,12.2.2 Method of preparing test specimens,12.2.3 Specimen thickness,12.2.4 Conditioning procedure used,12.2.5 Atmospheric conditions in test room,12.2.6 Number of specimens tested,12.2.7 Speed of testing,
45、12.2.8 Yield strength (if any), average value, and standarddeviation,12.2.9 Tensile strength, average value, and standard devia-tion,12.2.10 Tensile strength at break, average value, and stan-dard deviation,12.2.11 Percentage elongation at break, average value, andstandard deviation,12.2.12 Percenta
46、ge elongation at the yield point, averagevalue, and standard deviation (if desired),12.2.13 Date of test, and12.2.14 Date of test method.13. Precision and Bias13.1 PrecisionTable 1 and Table 2 are based on a roundrobin conducted in 1995 in accordance with Practice E691,involving two materials tested
47、 by seven laboratories. Polybu-tylene specimens were die cut from tubing. Polyamide(imide)specimens were injection molded. For each material, all of thespecimens were prepared at one source. Each test result is theaverage of five individual determinations, each on a previouslyuntested specimen. Each
48、 laboratory obtained two test resultsfor each material. (WarningThe following explanations of rand R (13.1.1-13.1.1.3) are only intended to present a mean-ingful way of considering the approximate precision of this testmethod. The data in Table 1 and Table 2 should not be appliedrigorously to the ac
49、ceptance or rejection of material, as thosedata are specific to the round robin and may not be represen-tative of other lots, conditions, materials, or laboratories. Usersof this test method should apply the principles outlined inPractice E691 to generate data specific to their laboratory andmaterials, or between specific laboratories. The principles of13.1.1-13.1.1.3 would then be valid for such data.)13.1.1 Concept of r and RIf Srand SRhave beencalculated from a large enough body of data, and for testresults that were averages from testing five specimen
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