1、Designation: D 1708 06aStandard Test Method forTensile Properties of Plastics by Use of MicrotensileSpecimens1This standard is issued under the fixed designation D 1708; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 mate
3、rial 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 12086-2:1955. Ingeneral, this test method is superseded for general use by eitherTest Methods D 882 or Test Method D 638. Th
4、e very smallType V specimen in Test Method D 638 is the recommendedspecimen 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
5、testedunder 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 modulu
6、s, seeTest Method D 638 or Test Methods D 882.1.4 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 brackets are for information only.1.6 This standard does not purport
7、 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.NOTE 1There is no equivalent or similar ISO stand
8、ard.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 638 Test Method for Tensile Properties of PlasticsD 882 Test Method for Tensile Properties of Thin PlasticSheetingD 883 Terminology Relating to PlasticsD 4000 Classification System for Specifying Pla
9、stic Mate-rialsE 691 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 De
10、finitions: Definitions of terms applying to this testmethod appear in Terminology D 883 and Test Method D 638,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, references
11、hould be 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 spe
12、cifications, then the default conditions hereinapply. Table 1 of Classification System D 4000 lists the ASTMmaterials standards that currently exist.5. Apparatus5.1 The apparatus shall be as specified in Test MethodD 638, with the following exceptions:5.1.1 GripsSerrated grips faces should be used w
13、ith care,since 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 D2
14、0 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1959. Last previous edition approved in 2006 as D 1708 - 06.2For referenced ASTM standards, visit the ASTM website, www.
15、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, 25 W. 43rd St., 4thFloor, New York, NY 10036.1*A Summary of Change
16、s 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 grip separationbetween upper and lo
17、wer 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 as specified in Section 8.5.1.3 The
18、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 total longitudinal deformationbetween t
19、he 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 the test. The instrument shall be esse
20、ntially 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 function of the extension or as a funct
21、ion 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 mm0.0001 in. or less.6. Test Specimens6.1 Microtensile test specimens sh
22、all 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 beprepared by injection molding or compress
23、ion 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 paper (No. 00 or finer). The finishin
24、g 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 gripping improved by the use of largerta
25、bs 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 each samplein the case of anisotropic ma
26、terials.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 Speed of testing is the velocity of separ
27、ation 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 designatedspeed according to Test Met
28、hod D 638. Speeds giving rates ofstraining approximating those given in Test Method D 638 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 speeds are 0.20 to 0.25 times the speeds designa
29、ted inTest Method D 638, since the effective gauge length of barsspecified in the latter test method is 4 to 5 times that of themicrotensile test specimens. When the speed of testing is notspecified, Speed B shall be used.9. Conditioning9.1 ConditioningCondition the test specimens at 23 62C 73.4 6 3
30、.6F and 50 6 5 % relative humidity for not lessthan 40 h prior to test in accordance with Procedure A ofPractice D 618, unless otherwise specified by contract or therelevant ASTM material specification. Reference pre-test con-ditioning, to settle disagreements, shall apply tolerances of61C 1.8F and
31、62 % relative humidity.9.2 Test ConditionsConduct the tests at 23 6 2C 73.4 63.6F and 50 6 5 % relative humidity, unless otherwisespecified by contract or the relevant ASTM material specifica-tion. Reference testing conditions, to settle disagreements,shall apply tolerances of 61C 1.8F and 62 % rela
32、tivehumidity.10. Procedure10.1 Test specimens shall be tested at the standard labora-tory atmosphere as defined in Practice D 618, 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
33、the thickness to the nearest0.0025 mm 0.0001 in. 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.TABLE 1 Tensile Strength at Break for Seven Laboratories andTwo Materials, MPaMaterialTestSpeed,mm/minAverage SrASRBr
34、CRDPolyamide(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 deviations of the test resultsfrom all of the participating laboratories:Sr5 S
35、1!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-laboratory reproducibility limit, R =2.83 SR.D 1708 06a210.3 Set the testing machine
36、 so that the distance between theupper and lower (or opposing) grips is 22.00 6 0.05 mm0.866 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
37、-mm0.886-in. gauge block or a pair of 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 cent
38、erline of the grips of the test machine. Tighten the grips evenlyNOTE 1All dimensions are in millimetres.FIG. 1 Microtensile Die and Test SpecimenD 1708 06a3and firmly to the degree necessary to prevent slippage of thespecimen during the test, but not to the point where thespecimen would be crushed.
39、10.5 Set the speed control at the speed 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 Yi
40、eld Strength, Tensile Strength, and Tensile Strength atBreakCalculate the yield strength, tensile strength, andtensile strength at break in accordance with Test MethodD 638.11.2 Percentage Elongation at BreakCalculate the per-centage elongation at break by dividing the elongation (exten-sion) at the
41、 moment of rupture of the specimen by the 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 elon
42、gation (extension) at the yield point by 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 D 638.12. Report12.1 Re
43、sults of this test method shall not be reported ashaving been obtained in accordance with Test Methods D 882or Test Method D 638 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
44、 tested, includ-ing type, source, manufacturers 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 o
45、f specimens tested,12.2.7 Speed of testing,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 va
46、lue, andstandard deviation,12.2.12 Percentage 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 P
47、ractice E 691,involving two materials tested 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,
48、 each on a previouslyuntested specimen. Each 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
49、 2 should not be appliedrigorously to the acceptance 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 E 691 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 e
