ASTM D7812-22

Standard Test Method for Tensile Testing of Aramid Paper

SIGNIFICANCE AND USE
5.1 The levels of tensile properties obtained when testing aramid paper are dependent on the age and history of the specimen and on the specific conditions used during the test. Among these conditions are rate of stretching, type of clamps, gauge length of specimen, temperature and humidity of the atmosphere, rate of airflow across the specimen, and temperature and moisture content of the specimen. Testing conditions accordingly are specified precisely to obtain reproducible test results on a specific sample.  
5.2 Tensile strength is used in engineering calculations when designing various types of products.  
5.3 Elongation of the paper is taken into consideration in the design and engineering of reinforced products because of its effect on uniformity of the finished product and its dimensional stability during service.  
5.4 Stiffness is a measure of the resistance of the paper to extension as a force is applied.  
5.5 Tensile Energy Absorption is dependent on the relationship of force to elongation. It is a measure of the ability of a textile structure to absorb mechanical energy. Tensile Energy Absorption is work-to-break per area.  
5.6 It should be emphasized that, although the preceding parameters are related to the performance of the product, the actual configuration of the product is significant. Shape, size, and internal construction also can have appreciable effects on product performance. It is not possible, therefore, to evaluate the performance of the end product in terms of the reinforcing material alone.  
5.7 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate test results were obtained, and that are randomly assign...
SCOPE
1.1 This test method covers the tensile testing of aramid paper with thickness less than 1 mm. This test method includes testing procedures only and includes no specifications or tolerances.  
1.2 The procedures given in this test method are for use with computer-controlled constant-rate-of-elongation tensile testing equipment.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2022
• ICS: 59.100.30 - Aramide materials
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.19 - Industrial Fibers and Metallic Reinforcements

Relations

• Refers: ASTM D4848-98(2018) - Standard Terminology Related to Force, Deformation and Related Properties of Textiles
• Effective Date: 01-Sep-2018
• Refers: ASTM D123-17 - Standard Terminology Relating to Textiles
• Effective Date: 01-Mar-2017
• Refers: ASTM D123-15b - Standard Terminology Relating to Textiles
• Effective Date: 15-Sep-2015
• Refers: ASTM D123-15a - Standard Terminology Relating to Textiles
• Effective Date: 01-Sep-2015
• Refers: ASTM D123-15 - Standard Terminology Relating to Textiles
• Effective Date: 01-Apr-2015
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM D374M-13 - Standard Test Methods for Thickness of Solid Electrical Insulation (Metric) (Withdrawn 2016)
• Effective Date: 01-Nov-2013
• Refers: ASTM D123-13a - Standard Terminology Relating to Textiles
• Effective Date: 15-Jun-2013
• Refers: ASTM D123-13ae1 - Standard Terminology Relating to Textiles
• Effective Date: 15-Jun-2013
• Refers: ASTM D123-13 - Standard Terminology Relating to Textiles
• Effective Date: 15-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM D6477-13 - Standard Terminology Relating to Tire Cord, Bead Wire, Hose Reinforcing Wire, and Fabrics
• Effective Date: 01-Jan-2013
• Refers: ASTM D4848-98(2012) - Standard Terminology Related to Force, Deformation and Related Properties of Textiles
• Effective Date: 01-Jun-2012
• Refers: ASTM D123-12e1 - Standard Terminology Relating to Textiles
• Effective Date: 01-Feb-2012

Overview

ASTM D7812-22: Standard Test Method for Tensile Testing of Aramid Paper is an internationally recognized standard from ASTM International. It provides specific procedures for determining the tensile properties of aramid paper with a thickness less than 1 mm, using computer-controlled, constant-rate-of-elongation tensile testing machines. The standard ensures reproducibility and comparability of test results by prescribing detailed conditions for all aspects of sample preparation, conditioning, and testing. Given the importance of aramid paper in high-performance and safety-critical applications, such as electrical insulation and reinforcement, accurate measurement of its tensile properties is essential.

Key Topics

• Tensile Strength: Defines the maximum force the aramid paper can withstand before breaking, a vital parameter in engineering design.
• Elongation at Break: Measures the ability of the paper to stretch under load, affecting product uniformity and dimensional stability.
• Stiffness & Stiffness Index: Indicates the resistance of aramid paper to extension and its stiffness relative to mass per unit area.
• Tensile Energy Absorption: Quantifies the mechanical energy the aramid paper can absorb before failure.
• Sample Preparation & Conditioning: Precise sample cutting, environmental conditioning (temperature, humidity), and construction details are critical for valid results.
• Reporting & Repeatability: Requirements for reporting conditions, sample details, and statistical measures to ensure comparability.

Applications

The tensile properties measured by ASTM D7812-22 are critical for a variety of industrial and engineering uses, including:

• Electrical Insulation: Tensile strength and elongation are used in the design and quality assurance of aramid papers for transformers, motors, and electronic insulation products.
• Reinforced Composites: Elongation and stiffness are important for ensuring the mechanical stability of composites used in aerospace, automotive, and civil engineering.
• Quality Control: Manufacturers and end-users rely on standardized tensile test results for material qualification, regulatory compliance, and performance verification.
• Research and Development: Consistent and reproducible data on tensile properties support innovation in new aramid-based products.

Related Standards

Several ASTM standards are referenced in ASTM D7812-22, providing broader context and technical definitions relevant to aramid paper testing:

• ASTM D76 – Specification for Tensile Testing Machines for Textiles
• ASTM D123 – Terminology Relating to Textiles
• ASTM D202 – Test Methods for Sampling and Testing Untreated Paper Used for Electrical Insulation
• ASTM D374M – Test Methods for Thickness of Solid Electrical Insulation (Metric)
• ASTM D1776 – Practice for Conditioning and Testing Textiles
• ASTM D4848 – Terminology Related to Force, Deformation and Related Properties of Textiles
• ASTM E691 – Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Adhering to ASTM D7812-22 promotes reliable, reproducible results in the evaluation of aramid papers, ensuring compatibility and consistency across laboratories and industries worldwide.

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Keywords: ASTM D7812-22, tensile testing, aramid paper, tensile strength, elongation, stiffness, tensile energy absorption, quality control, electrical insulation, reinforced composites, standard test method.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7812 − 22
Standard Test Method for
Tensile Testing of Aramid Paper
This standard is issued under the fixed designation D7812; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope D4848 Terminology Related to Force, Deformation and
Related Properties of Textiles
1.1 This test method covers the tensile testing of aramid
D6477 Terminology Relating to Tire Cord, Bead Wire, Hose
paper with thickness less than 1 mm.This test method includes
Reinforcing Wire, and Fabrics
testing procedures only and includes no specifications or
E691 Practice for Conducting an Interlaboratory Study to
tolerances.
Determine the Precision of a Test Method
1.2 Theproceduresgiveninthistestmethodareforusewith
E177 Practice for Use of the Terms Precision and Bias in
computer-controlled constant-rate-of-elongation tensile testing
ASTM Test Methods
equipment.
1.3 The values stated in SI units are to be regarded as 3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions—The following terms are relevant to this
standard.
standard: aramid paper, breaking force, elongation, initial
1.4 This standard does not purport to address all of the
modulus, tensile strength, and Tensile Energy Absorption.
safety concerns, if any, associated with its use. It is the
3.1.1 For definitions of terms related to industrial fibers and
responsibility of the user of this standard to establish appro-
metallic reinforcements, refer to Terminology D6477.
priate safety, health, and environmental practices and deter-
3.1.2 For definitions of terms related to force and deforma-
mine the applicability of regulatory limitations prior to use.
tion in textiles, refer to Terminology D4848.
1.5 This international standard was developed in accor-
3.1.3 For definitions of other terms related to textiles, refer
dance with internationally recognized principles on standard-
to Terminology D123.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Summary of Test Method
mendations issued by the World Trade Organization Technical
4.1 A conditioned sample of aramid paper is clamped in a
Barriers to Trade (TBT) Committee.
tensile testing machine and then stretched or loaded until
2. Referenced Documents
broken.
2.1 ASTM Standards:
4.2 The output of a constant-rate-of-extension (CRE) tensile
D76 Specification for Tensile Testing Machines for Textiles
testingmachinecanbeconnectedwithelectronicrecordingand
D123 Terminology Relating to Textiles
computing equipment, which may be programmed to calculate
D202 Test Methods for Sampling and Testing Untreated
and print the test results of tensile properties of interest.
Paper Used for Electrical Insulation
4.3 Breaking force and elongation are determined directly.
D374M Test Methods for Thickness of Solid Electrical
Modulus and Tensile Energy Absorption are calculated from
Insulation (Metric) (Withdrawn 2016)
the force-elongation curve.
D1776 Practice for Conditioning and Testing Textiles
5. Significance and Use
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
5.1 The levels of tensile properties obtained when testing
and is the direct responsibility of Subcommittee D13.19 on Industrial Fibers and
Metallic Reinforcements.
aramid paper are dependent on the age and history of the
Current edition approved Nov. 1, 2022. Published December 2022. Originally
specimen and on the specific conditions used during the test.
approved in 2016. Last previous edition approved in 2016 as D3512 – 16. DOI:
Among these conditions are rate of stretching, type of clamps,
10.1520/D7812-22.
gauge length of specimen, temperature and humidity of the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
atmosphere, rate of airflow across the specimen, and tempera-
Standards volume information, refer to the standard’s Document Summary page on
ture and moisture content of the specimen. Testing conditions
the ASTM website.
accordingly are specified precisely to obtain reproducible test
The last approved version of this historical standard is referenced on
www.astm.org. results on a specific sample.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7812 − 22
5.2 Tensile strength is used in engineering calculations 6.5 SpecimenCutter—adevicecapableofcuttingspecimens
when designing various types of products. for testing that are uniform in width to within 60.2 mm of the
specified specimen width and with edges parallel to within
5.3 Elongationofthepaperistakenintoconsiderationinthe
60.1 mm. A double-blade strip cutter or a laser cutter is
design and engineering of reinforced products because of its
satisfactory for this requirement. Other cutting dies may also
effect on uniformity of the finished product and its dimensional
be used, provided they are found to comply with or exceed the
stability during service.
tolerances within this standard. Single-blade paper cutters do
5.4 Stiffness is a measure of the resistance of the paper to
not comply with the requirements for a specimen cutter for
extension as a force is applied.
purposes of this test method.
5.5 Tensile EnergyAbsorption is dependent on the relation-
7. Sampling, Test Specimens
ship of force to elongation. It is a measure of the ability of a
textile structure to absorb mechanical energy. Tensile Energy 7.1 For acceptance testing, sample each lot as directed in
Absorption is work-to-break per area. Test Methods D202. Take the number of samples for testing
specified for the specific property measurement to be made.
5.6 It should be emphasized that, although the preceding
7.2 Conditioning—Bring all specimens to equilibrium in the
parameters are related to the performance of the product, the
atmosphere prior to sample cutting as directed in Prac-
actual configuration of the product is significant. Shape, size,
tice D1776 for Aramids.
and internal construction also can have appreciable effects on
product performance. It is not possible, therefore, to evaluate
7.3 Preparation—Cut the test specimens from each condi-
the performance of the end product in terms of the reinforcing
tioned test unit of the sample. The two options for specimen
material alone.
size are:
Type 1: Length 205 mm 6 3 mm; width 15.0 mm 6 0.2 mm
5.7 If there are differences of practical significance between
Type 2: Length 205 mm 6 3 mm; width 25.4 mm 6 0.3 mm
reported test results for two laboratories (or more), compara-
tive tests should be performed to determine if there is a
7.4 Number of Specimens—At least five or preferably ten
statistical bias between them, using competent statistical assis-
specimens per sample in machine, and at least five or prefer-
tance. As a minimum, test samples should be used that are as
ably ten specimens per sample in the cross-machine direction.
homogeneous as possible, that are drawn from the material
from which the disparate test results were obtained, and that
8. Conditioning
are randomly assigned in equal numbers to each laboratory for
8.1 Bring all specimens to equilibrium in the atmosphere
testing. Other materials with established test values may be
prior to testing as directed in Practice D1776 for Aramids.
used for this purpose.The test results from the two laboratories
should be compared using a statistical test for unpaired data, at
9. Procedure
a probability level chosen prior to the testing series. If a bias is
9.1 Sample Preparation—Cut the specimens according to
found, either its cause must be found and corrected, or future
Section 7.
test results must be adjusted in consideration of the known
bias. 9.2 Conditioning—Condition the samples as directed in 8.1.
9.3 Measurement of Thickness—Measure the thickness of
6. Apparatus
the specimen according to Test Method D374M.
6.1 Thickness—Micrometer, conforming to the specifica-
9.4 Measurement of Mass Per Unit Area—Measure the
tions as given in Test Method D374M.
grams per square meter by weighing the individual specimens
as listed in 9.1.
6.2 Grammage—Weighing device, readable and accurate to
within 0.25 % of the applied load. When in use, the weighing
9.5 Gauge Length—The gauge length shall have a total
device shall be shielded from air currents.
length for type 1 specimen size of 100 mm 6 1 mm and for
type 2 of 127 mm 6 1 mm between the jaw faces.
6.3 Tensile Testing Machine—Asingle-strand tensile testing
machine of the constant rate of extension (CRE) type. The 9.6 Crosshead Travel Rate—The crosshead travel rate is
specifications and methods of calibration and verification of
10 % of the nominal gauge length of the specimen. This rate of
these machines shall conform to Specification D76.The testing
crosshead travel generally results in specimen rupture between
machine shall be equipped with a data-acquisition system.
10 s and 30 s. In cases where rupture consistently requires
greater than 30 s, a more rapid rate of crosshead travel must be
6.4 Clamps—Side action clamps with rubber-coated flat jaw
used, so that specimen rupture occurs between 10 s and 30 s.
faces. The test specimen shall be held in such a way that
Where a crosshead travel rate other than that stated above is
slippage relative to the grips is prevented as much as possible.
used, the actual crosshead travel rate must be reported.
The width of the jaw faces should be equal to or larger than the
sample width. If the clamps are of the air-actuated type, adjust 9.7 Slack Start Procedure—Clamp one end of the specimen
the air pressure to prevent specimens slipping in the jaws, but between the jaws of one of the clamps and close it. Place the
keep the air pressure below the level that will cause specimens otherendofthespecimenthroughthejawsofthesecondclamp
to break at the edge of the jaws. If the break is within 5 mm of and keep the specimen just slack (zero tension) and close the
the edge, the result must be discarded. clamp, taking care that the paper is positioned in the centerline
D7812 − 22
of the jaws of the clamp. This slack start procedure has the BT
TI 5 (4)
effect that the nominal gauge length of the specimen will be QM
slightly greater as specified in 9.5.
where:
9.8 Tensile Testing—Operate the testing machine at the rate
BT = tensile strength, N/m, and
as specified in 9.6 and stretch the specimen until it ruptures.
QM = specimen mass per unit area, g/m .
Discard specimens that break in the jaws or within 5 mm of the
Report results as stated in Section 11.
nip of the jaws. Report the discarded specimen.
10.5 Breaking Length—BL in m. Breaking length is that
10. Calculation or Interpretation of Results
length in metres under which the sample will fail under its own
10.1 Thickness—T in mm. Measure the thickness of the
weight.
individual specimen conforming to Test Methods D374M.
BT
Report results as stated in Section 11.
BL 5 ·1000 (5)
QM·g
where:
10.2 Mass Per Unit Area—QM in g/m . Calculate the areal
BL = breaking length, m,
weight of the individual specimen by:
BT = tensile strength, N/m,
M
QM = specimen mass per unit area, g/m , and
QM 5 ·10 (1)
L ·W 2 2
g = constant of gravity, m/s (≈ 9.8 m/s ).
where:
Report results as stated in Section 11.
QM = mass per unit area, g/m ,
M = mass of the specimen, g,
10.5.1 Elongation at Break—EAB in %. Determine the
L = specimen length, mm, and
elongation at break of each conditioned specimen when deter-
W = specimen width, mm.
mined at its breaking force point. With the use of slack start, a
correction of gauge length is required. The procedure for
Report results as stated in Section 11.
determining the slack is as shown in Fig. 1. Take force levels
F1=5% BF and F2=10% BF. Determine the extensions e1
10.2.1 Breaking Force—BF in N. When the specimen
and e2 from the extension-force graph at the force levels F1
breaks, read the breaking force (maximum force) in newtons.
and F2 respectively. Compute the intercept at the extension
Report results as stated in Section 11.
axis using:
e1F2 2 e2F1
10.3 Tensile Strength—BT in N/m. Compute the tensile
∆L 5 (6)
F2 2 F1
strength by dividing the breaking force by the specimen width
W:
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D7812 − 16 D7812 − 22
Standard Test Method for
Tensile Testing of Aramid Paper
This standard is issued under the fixed designation D7812; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the tensile testing of aramid paper with thickness less than 1 mm. This test method includes testing
procedures only and includes no specifications or tolerances.
1.2 The procedures given in this test method are for use with computer-controlled constant-rate-of-elongation tensile testing
equipment.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D76 Specification for Tensile Testing Machines for Textiles
D123 Terminology Relating to Textiles
D202 Test Methods for Sampling and Testing Untreated Paper Used for Electrical Insulation
D374M Test Methods for Thickness of Solid Electrical Insulation (Metric) (Withdrawn 2016)
D1776 Practice for Conditioning and Testing Textiles
D4848 Terminology Related to Force, Deformation and Related Properties of Textiles
D6477 Terminology Relating to Tire Cord, Bead Wire, Hose Reinforcing Wire, and Fabrics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.19 on Industrial Fibers and Metallic
Reinforcements.
Current edition approved Jan. 1, 2016Nov. 1, 2022. Published February 2016December 2022. Originally approved in 2016. Last previous edition approved in 2016 as
D3512 – 16. DOI: 10.1520/D7812–16.10.1520/D7812-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7812 − 22
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
3. Terminology
3.1 For definitions of other terms related to textiles, refer to Terminology D123.
3.1 Definitions—For definitions of terms related to force and deformation in textiles, refer to Terminology The following terms
are relevant to this standard: aramid paper, breaking force, elongation, initial modulus, tensile strength, and Tensile Energy
Absorption.D6477.
3.1.1 For definitions of terms related to industrial fibers and metallic reinforcements, refer to Terminology D6477.
3.1.2 For definitions of terms related to force and deformation in textiles, refer to Terminology D4848.
3.1.3 For definitions of other terms related to textiles, refer to Terminology D123.
3.3 Definitions:
3.3.1 aramid paper, n—planar structures deposited from an aqueous suspension that has a thickness less than 1 mm containing 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 Method
4.1 A conditioned sample of aramid paper is clamped in a tensile testing machine and then stretched or loaded until broken.
4.2 The output of a constant-rate-of-extension (CRE) tensile testing machine can be connected with electronic recording and
computing equipment, which may be programmed to calculate and print the test results of tensile properties of interest.
4.3 Breaking force and elongation are determined directly. Modulus and Tensile Energy Absorption are calculated from the
force-elongation curve.
5. Significance and Use
5.1 The levels of tensile properties obtained when testing aramid paper are dependent on the age and history of the specimen and
on the specific conditions used during the test. Among these conditions are rate of stretching, type of clamps, gauge length of
specimen, temperature and humidity of the atmosphere, rate of airflow across the specimen, and temperature and moisture content
of the specimen. Testing conditions accordingly are specified precisely to obtain reproducible test results on a specific sample.
5.2 Tensile strength is used in engineering calculations when designing various types of products.
5.3 Elongation of the paper is taken into consideration in the design and engineering of reinforced products because of its effect
on uniformity of the finished product and its dimensional stability during service.
5.4 Stiffness is a measure of the resistance of the paper to extension as a force is applied.
5.5 Tensile Energy Absorption is dependent on the relationship of force to elongation. It is a measure of the ability of a textile
structure to absorb mechanical energy. Tensile Energy Absorption is work-to-break per area.
5.6 It should be emphasized that, although the preceding parameters are related to the performance of the product, the actual
configuration of the product is significant. Shape, size, and internal construction also can have appreciable effects on product
performance. It is not possible, therefore, to evaluate the performance of the end product in terms of the reinforcing material alone.
5.7 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests
D7812 − 22
should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum,
test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate test
results were obtained, and that are randomly assigned in equal numbers to each laboratory for testing. Other materials with
established test values may be used for this purpose. The test results from the two laboratories should be compared using a
statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be
found and corrected, or future test results must be adjusted in consideration of the known bias.
6. Apparatus
6.1 Thickness—Micrometer, conforming to the specifications as given in Test Method D374M.
6.2 Grammage—Weighing device, readable and accurate to within 0.25 % of the applied load. When in use, the weighing device
shall be shielded from air currents.
6.3 Tensile Testing Machine—A single-strand tensile testing machine of the constant rate of extension (CRE) type. The
specifications and methods of calibration and verification of these machines shall conform to Specification D76. The testing
machine shall be equipped with a data-acquisition system.
6.4 Clamps—Side action clamps with rubber-coated flat jaw faces. The test specimen shall be held in such a way that slippage
relative to the grips is prevented as much as possible. The width of the jaw faces should be equal to or larger than the sample width.
If the clamps are of the air-actuated type, adjust the air pressure to prevent specimens slipping in the jaws, but keep the air pressure
below the level that will cause specimens to break at the edge of the jaws. If the break is within 5 mm of the edge, the result must
be discarded.
6.5 Specimen Cutter—a device capable of cutting specimens for testing that are uniform in width to within 60.2 mm of the
specified specimen width and with edges parallel to within 60.1 mm. A double-blade strip cutter or a laser cutter is satisfactory
for this requirement. Other cutting dies may also be used, provided they are found to comply with or exceed the tolerances within
this standard. Single-blade paper cutters do not comply with the requirements for a specimen cutter for purposes of this test
method.
7. Sampling, Test Specimens
7.1 For acceptance testing, sample each lot as directed in Test Methods D202. Take the number of samples for testing specified
for the specific property measurement to be made.
7.2 Conditioning—Bring all specimens to equilibrium in the atmosphere prior to sample cutting as directed in Practice D1776 for
Aramids.
7.3 Preparation—Cut the test specimens from each conditioned test unit of the sample. The two options for specimen size are:
Type 1: Length 205 6 3 mm; width 15.0 6 0.2 mmType 1: Length 205 mm 6 3 mm; width 15.0 mm 6 0.2 mm
Type 2: Length 205 6 3 mm; width 25.4 6 0.3 mmType 2: Length 205 mm 6 3 mm; width 25.4 mm 6 0.3 mm
7.4 Number of Specimens—At least five or preferably ten specimens per sample in machine, and at least five or preferably ten
specimens per sample in the cross-machine direction.
8. Conditioning
8.1 Bring all specimens to equilibrium in the atmosphere prior to testing as directed in Practice D1776 for Aramids.
9. Procedure
9.1 Sample Preparation—Cut the specimens according to Section 7.
9.2 Conditioning—Condition the samples as directed in 8.1.
9.3 Measurement of Thickness—Measure the thickness of the specimen according to Test Method D374M.
D7812 − 22
9.4 Measurement of Mass Per Unit Area—Measure the grams per square meter by weighing the individual specimens as listed in
9.1.
9.5 Gauge Length—The gauge length shall have a total length for type 1 specimen size of 100 100 mm 6 1 mm and for type 2
of 127 6127 mm 6 1 mm between the jaw faces.
9.6 Crosshead Travel Rate—The crosshead travel rate is 10 % of the nominal gauge length of the specimen. This rate of crosshead
travel generally results in specimen rupture between 1010 s and 30 s. In cases where rupture consistently requires greater than 30 s,
a more rapid rate of crosshead travel must be used, so that specimen rupture occurs between 10 and 10 s and 30 s. Where a
crosshead travel rate other than that stated above is used, the actual crosshead travel rate must be reported.
9.7 Slack Start Procedure—Clamp one end of the specimen between the jaws of one of the clamps and close it. Place the other
end of the specimen through the jaws of the second clamp and keep the specimen just slack (zero tension) and close the clamp,
taking care that the paper is positioned in the centerline of the jaws of the clamp. This slack start procedure has the effect that the
nominal gauge length of the specimen will be slightly greater as specified in 9.5.
9.8 Tensile Testing—Operate the testing machine at the rate as specified in 9.79.6 and stretch the specimen until it ruptures. Discard
specimens that break in the jaws or within 5 mm of the nip of the jaws. Report the discarded specimen.
10. Calculation or Interpretation of Results
10.1 Thickness—T in mm. Measure the thickness of the individual specimen conforming to Test Methods D374M.
Report results as stated in Section 11.
10.2 Mass Per Unit Area—QM in g/m . Calculate the areal weight of the individual specimen by:
M
QM 5 ·10 (1)
L ·W
where:
QM = mass per unit area, g/m ,
M = mass of the specimen, g,
L = specimen length, mm, and
W = specimen width, mm.
Report results as stated in Section 11.
10.2.1 Breaking Force—BF in N. When the specimen breaks, read the breaking force (maximum force) in newtons.
Report results as stated in Section 11.
10.3 Tensile Strength—BT in N/m. Compute the tensile strength by dividing the breaking force by the specimen width W:
BF
BT 5 ·1000 (2)
W
where:
BT = tensile strength, N/m,
BF = breaking force, N, and
W = specimen width, mm.
Report results as stated in Section 11.
D7812 − 22
10.4 Tensile Stress at Break—SB in MPa. Compute the tensile stress by dividing the breaking force by the sample cross-section
area:
BF
SB 5 (3)
W · T
where:
SB = stress at break, MPa,
BF = breaking force, N,
W = specimen width, mm, and
T = specimen thickness, mm.
Report results as stated in Section 11.
10.4.1
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