Designation: D 1708 – 02a

Standard Test Method for

Tensile Properties of Plastics By Use of Microtensile
Specimens1
This standard is issued under the fixed designation D 1708; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript 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 D 882 Test Methods for Tensile Properties of Thin Plastic

1.1 This test method covers certain material specifications Sheeting2
for which a history of data has been obtained using the standard D 883 Terminology Relating to Plastics2
microtensile specimen. The specimen geometry has been D 4000 Classification System for Specifying Plastic Mate-
changed to be equivalent to that of ISO 12086-2:1955. In rials3
general, this test method is superseded for general use by either D 4066 Specification for Nylon Injection and Extrusion
Test Methods D 882 or Test Method D 638. The very small Materials3
Type V specimen in Test Method D 638 is the recommended D 4968 Guide for Annual Review of Test Methods and
specimen when limited amounts of material are available. Specifications for Plastics4
1.2 This test method covers the determination of the com- D 5947 Test Methods for Physical Dimensions of Solid
parative tensile strength and elongation properties of plastics in Plastics Specimens4
the form of standard microtensile test specimens when tested E 691 Practice for Conducting an Interlaboratory Study to
under defined conditions of pretreatment, temperature, humid- Determine the Precision of a Test Method5
ity, and testing machine speed. It can be used for specimens of 2.2 ISO Standard:
any thickness up to 3.2 mm (1⁄8 in.), including thin films. ISO 12086-2:1995 Plastics—Fluoropolymer Dispersion,
1.3 This test method cannot be used for the determination of Moulding, and Extrusion Materials—Part 2 Preparation of
modulus of elasticity. For the determination of modulus, see Test Specimens and Determination of Properties6
Test Method D 638 or Test Methods D 882. 3. Terminology
1.4 Test data obtained by this test method are relevant and
appropriate for use in engineering design. 3.1 Definitions: Definitions of terms applying to this test
1.5 The values stated in SI units are to be regarded as the method appear in Terminology D 883 and Test Method D 638,
standard. The values given in parentheses are for information Annex A2.
only. 4. Significance and Use
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 4.1 This test method provides data for quality control and
responsibility of the user of this standard to establish appro- acceptance or rejection under specifications.
priate safety and health practices and determine the applica- 4.2 Before proceeding with this test method, reference
bility of regulatory limitations prior to use. should be made to the ASTM specification of the material
being tested. Any test specimen preparation, conditioning,
NOTE 1—There is no equivalent or similar ISO standard. dimensions, or testing parameters, or combination thereof,
2. Referenced Documents covered in the materials specification shall take precedence
over those mentioned in this test method. If there are no
2.1 ASTM Standards: material specifications, then the default conditions herein
D 618 Practice for Conditioning Plastics for Testing2 apply. Table 1 of Classification System D 4000 lists the ASTM
D 638 Test Method for Tensile Properties of Plastics2 materials standards that currently exist.

1 3
This test method is under the jurisdiction of ASTM Committee D20 on Plastics Annual Book of ASTM Standards, Vol 08.02.
4
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties. Annual Book of ASTM Standards, Vol 08.03.
5
Current edition approved August 10, 2002. Published October 2002. Originally Annual Book of ASTM Standards, Vol 14.02.
6
published as D 1708 – 59 T. Last previous edition D 1708 – 02. Available from American National Standards Institute, 25 W. 43rd St., 4th
2
Annual Book of ASTM Standards, Vol 08.01. Floor, New York, NY 10036.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

1
 D 1708 – 02a
TABLE 1 Tensile Strength at Break for Seven Laboratories and 6.2 All surfaces of the specimen shall be free of visible
Two Materials, MPa flaws, scratches, or imperfections. Marks left by coarse ma-
Test chining operations shall be carefully removed with a fine file or
Material Speed, Average SrA SRB rC RD
mm/min
abrasive, and the filed surfaces shall then be smoothed with
Polyamide(imide) 1.3 193.6 1.60 5.48 4.48 15.3 abrasive paper (No. 00 or finer). The finishing sanding strokes
Polybutylene 12.7 31.3 0.80 2.75 9.12 9.12 shall be made in the direction parallel to the long axis of the
A
Sr is the within-laboratory standard deviation for the indicated material. It is test specimen.
obtained by pooling the within-laboratory standard deviations of the test results
from all of the participating laboratories: NOTE 3—Tabs shown in Fig. 1 are minimum size for adequate gripping.
Sr 5 @@~S1!2 1 ~S2!2 1 ... 1 ~Sn!2#/n#1 / 2. (1) Shims may be required with thicker specimens to keep grips from
B
SR is the between-laboratories reproducibility, expressed as a standard
cocking. Handling is facilitated and gripping improved by the use of larger
deviation, for the indicated material.
C
r is the within-laboratory repeatability limit, r = 2.8 3 Sr. tabs wherever possible.
D
R is the between-laboratory reproducibility limit, R = 2.8 3 SR.
7. Number of Test Specimens
5. Apparatus 7.1 At least five test specimens shall be tested for each
5.1 The apparatus shall be as specified in Test Method sample in the case of isotropic materials.
D 638, with the following exceptions: 7.2 Ten test specimens, five normal to and five parallel to
5.1.1 Grips—Serrated grips faces should be used with care, the principal axis of anisotropy, shall be tested for each sample
since yielding or tearing at the grips may interfere with in the case of anisotropic materials.
measurement of elongation even when the specimen breaks in 7.3 Results obtained on test specimens that break at some
the reduced section. Grips with rubber coated faces are obvious fortuitous flaw or at the edge of the grips shall be
recommended for thin specimens. Care should be taken when discarded and retests made, unless such flaws constitute a
selecting and using self tightening grips. Those which move as variable, the effect of which it is desired to study.
they tighten and result in a change in the grip separation
between upper and lower grips are not satisfactory for this test 8. Speed of Testing
method. If the specimen tab is not long enough to prevent the
8.1 Speed of testing is the velocity of separation of the two
grip faces from cocking, shims should be inserted to provide
members (or grips) of the testing machine when running idle
more uniform clamping.
(under no load).
5.1.2 Drive Mechanism—The velocity of the drive mecha-
nism shall be regulated as specified in Section 8. 8.2 The speed of testing shall be chosen such that the rate of
5.1.3 The fixed and movable members, drive mechanism, straining shall be approximately the same as the rate of
and grips should be constructed of such materials and in such straining obtained when the material is tested at the designated
proportions that, after grip slack is taken up, the total elastic speed according to Test Method D 638. Speeds giving rates of
longitudinal deformation of the system constituted by these straining approximating those given in Test Method D 638 are
parts does not exceed 1 % of the total longitudinal deformation as follows:
Speed A 0.25 mm (0.01 in.)/min
between the grips at any time during the test. If this is not
Speed B 1 to 1.3 mm (0.04 to 0.05 in.)/min
possible, appropriate corrections shall be made in the calcula- Speed C 10 to 13 mm (0.4 to 0.5 in.)/min
tion of strain values. Speed D 100 to 130 mm (4 to 5 in.)/min
5.1.4 Extension Indicator—The extension indicator shall be
These speeds are 0.20 to 0.25 times the speeds designated in
capable of determining the distance between grips at any time
Test Method D 638, since the effective gage length of bars
during the test. The instrument shall be essentially free of
specified in the latter test method is 4 to 5 times that of the
inertia lag at the specified speed of testing, and shall be
microtensile test specimens. When the speed of testing is not
accurate to 61 % of extension or better.
specified, Speed B shall be used.
NOTE 2—It is desirable that the load indicator and the extension
indicator be combined into one instrument, which automatically records 9. Conditioning
the load as a function of the extension or as a function of time. In the latter
case, the conversion to a load-extension record can readily be made 9.1 Conditioning—Condition the test specimens at 23 6
because extension is proportional to time after the take-up of the initial 2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity for not less
grip slack. than 40 h prior to test in accordance with Procedure A of
5.1.5 Micrometers—Micrometers shall read to 0.0025 mm Practice D 618, unless otherwise specified by contract or the
(0.0001 in.) or less. relevant ASTM material specification. Reference pre-test con-
ditioning, to settle disagreements, shall apply tolerances of
6. Test Specimens 61°C (1.8°F) and 62 % relative humidity.
6.1 Microtensile test specimens shall conform to the dimen- 9.2 Test Conditions—Conduct the tests at 23 6 2°C (73.4 6
sions shown in Fig. 1. This specimen shall be prepared by 3.6°F) and 50 6 5 % relative humidity, unless otherwise
die-cutting or machining from sheet, plate, slab, or finished specified by contract or the relevant ASTM material specifica-
article. Dimensions of a die suitable for preparing die-cut tion. Reference testing conditions, to settle disagreements,
specimens are also shown in Fig. 1. Specimens may also be shall apply tolerances of 61°C (1.8°F) and 62 % relative
prepared by injection molding or compression molding. humidity.

2
 D 1708 – 02a

NOTE 1—All dimensions are in millimetres.

FIG. 1 Microtensile Die and Test Specimen

10. Procedure 0.0025 mm (0.0001 in.) for specimens less than 2.5 mm (0.1
10.1 Test specimens shall be tested at the standard labora- in.) thick, or to the nearest 0.025 mm (0.001 in.) for specimens
tory atmosphere as defined in Practice D 618, unless otherwise 2.5 mm (0.1 in.) or greater in thickness.
specified. 10.3 Set the testing machine so that the distance between the
10.2 Measure and record the minimum value of the cross- upper and lower (or opposing) grips is 22.00 6 0.05 mm
sectional area of each specimen. Measure the width to the (0.866 6 0.002 in.). This shall be measured with the grips in
nearest 0.025 mm (0.001 in.) and the thickness to the nearest the closed position.

3
 D 1708 – 02a
NOTE 4—This may easily be checked by the use of a 22.00-mm 12.2.12 Percentage elongation at the yield point, average
(0.886-in.) gage block or a pair of inside calipers. value, and standard deviation (if desired),
10.4 Place the specimen in the grips of the testing machine 12.2.13 Date of test, and
with the inside edge of each tab visible at the edge of the grip. 12.2.14 Date of test method.
To ensure uniform axial tensile stress within the gage length,
the axis of the test specimen should coincide with the center 13. Precision and Bias
line of the grips of the test machine. Tighten the grips evenly 13.1 Precision—Table 1 and Table 2 are based on a round
and firmly to the degree necessary to prevent slippage of the robin conducted in 1995 in accordance with Practice E 691,
specimen during the test, but not to the point where the involving two materials tested by seven laboratories. Polybu-
specimen would be crushed. tylene specimens were die cut from tubing. Polyamide(imide)
10.5 Set the speed control at the speed desired (8.2) and start specimens were injection molded. For each material, all of the
the machine. specimens were prepared at one source. Each test result is the
10.6 Record the load at the yield point (if one exists), the average of five individual determinations, each on a previously
maximum load carried by the specimen during the test, the load untested specimen. Each laboratory obtained two test results
at rupture, and the elongation (extension between grips) at the for each material.
moment of rupture. NOTE 5—Caution: The following explanations of r and R (13.1.1-
13.1.1.3 ) are only intended to present a meaningful way of considering
11. Calculation the approximate precision of this test method. The data in Table 1 and
11.1 Yield Strength, Tensile Strength, and Tensile Strength at Table 2 should not be applied rigorously to the acceptance or rejection of
Break—Calculate the yield strength, tensile strength, and material, as those data are specific to the round robin and may not be
tensile strength at break in accordance with Test Method representative of other lots, conditions, materials, or laboratories. Users of
D 638. this test method should apply the principles outlined in Practice E 691 to
generate data specific to their laboratory and materials, or between specific
11.2 Percentage Elongation at Break—Calculate the per- laboratories. The principles of 13.1.1-13.1.1.3 would then be valid for
centage elongation at break by dividing the elongation (exten- such data.
sion) at the moment of rupture of the specimen by the original
13.1.1 Concept of r and R—If Sr and SR have been calcu-
distance between tabs 22.00 6 0.05 mm (0.866 6 0.002 in.),
lated from a large enough body of data, and for test results that
and multiplying by one hundred. Report the percentage elon-
were averages from testing five specimens:
gation to two significant figures.
13.1.1.1 Repeatability Limit, r (Comparing two test results
11.3 Percentage Elongation at the Yield Point—Calculate
for the same material, obtained by the same operator using the
the percentage elongation at the yield point, if desired, by
same equipment on the same day)—The two test results should
dividing the elongation (extension) at the yield point by the
be judged not equivalent if they differ by more than the r value
original distance between tabs 22.250 6 0.051 mm (0.876 6
for that material.
0.002 in.), and multiplying by one hundred.
13.1.1.2 Reproducibility Limit, R (Comparing two test re-
11.4 Calculate the “average value” and standard deviation
sults for the same material, obtained by different operators
for each property in accordance with Test Method D 638.
using different equipment in different laboratories)—The two
12. Report test results should be judged not equivalent if they differ by
12.1 Results of this test method shall not be reported as more than the R value for that material.
having been obtained in accordance with Test Methods D 882 13.1.1.3 Any judgment in accordance with 13.1.1.1 or
or Test Method D 638 regardless of any modifications that 13.1.1.2 would have an approximate 95 % (0.95) probability of
might be made to simulate those testing parameters. being correct.
12.2 Report the following information: 13.2 Bias—There are no recognized standards by which to
12.2.1 Complete identification of the material tested, includ- estimate the bias of this test method.
ing type, source, manufacturer’s code numbers, form, principal 14. Keywords
dimensions, previous history, and other pertinent information,
12.2.2 Method of preparing test specimens, 14.1 microtensile; plastics test method; tensile properties
12.2.3 Specimen thickness,
TABLE 2 Elongation at Break for Seven Laboratories and Two
12.2.4 Conditioning procedure used,
Materials, %
12.2.5 Atmospheric conditions in test room,
Test
12.2.6 Number of specimens tested, Material Speed, Average SrA SRB rC RD
12.2.7 Speed of testing, mm/min
12.2.8 Yield strength (if any), average value, and standard Polyamide(imide) 1.3 15.7 0.96 2.40 2.70 6.73
Polybutylene 12.7 196 8.94 16.1 25.0 45.2
deviation,
A
Sr is the within-laboratory standard deviation for the indicated material. It is
12.2.9 Tensile strength, average value, and standard devia- obtained by pooling the within-laboratory standard deviations of the test results
tion, from all of the participating laboratories:
12.2.10 Tensile strength at break, average value, and stan- Sr 5 @@~S1!2 1 ~S2!2 1 ... 1 ~Sn!2#/n#1 / 2. (2)
B
dard deviation, SR is the between-laboratories reproducibility, expressed as a standard
deviation, for the indicated material.
12.2.11 Percentage elongation at break, average value, and C
r is the within-laboratory repeatability limit, r = 2.8 3 Sr.
standard deviation, D
R is the between-laboratory reproducibility limit, R = 2.8 3 SR.

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 D 1708 – 02a
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