ASTM D4018-99(2008)
(Test Method)Standard Test Methods for Properties of Continuous Filament Carbon and Graphite Fiber Tows
Standard Test Methods for Properties of Continuous Filament Carbon and Graphite Fiber Tows
SIGNIFICANCE AND USE
The properties determined by these test methods are of value in material specifications, qualifications, data base generation, certification, research, and development.
These test methods are intended for the testing of fibers that have been specifically developed for use as reinforcing agents in advanced composite structures. The test results of an impregnated and consolidated fiber should be representative of the strength and modulus that are available in the material when used as intended. The performance of fibers in different resin systems can vary significantly so that correlations between results using these test methods and composite testing may not always be obtained.
The reproducibility of test results is dependent upon precise control over all test conditions. Resin type, content and distribution, curing process, filament alignment, gripping in the testing machine, and alignment in the testing machine are of special importance.
The measured strengths of fibers are not unique quantities and test results are strongly dependent on the test methods used. Therefore the test method described here will not necessarily give the same mean strengths or standard deviations as those obtained from single filaments, dry fibers, composite laminas, or composite laminates.
SCOPE
1.1 These test methods cover the preparation and tensile testing of resin-impregnated and consolidated test specimens made from continuous filament carbon and graphite yarns, rovings, and tows to determine their tensile properties.
1.2 These test methods also cover the determination of the density and mass per unit length of the yarn, roving, or tow to provide supplementary data for tensile property calculation.
1.3 These test methods include a procedure for sizing removal to provide the preferred desized fiber samples for density measurement. This procedure may also be used to determine the weight percent sizing.
1.4 These test methods include a procedure for determining the weight percent moisture adsorption of carbon or graphite fiber.
1.5 The values stated in SI units are to be regarded as the standard. The values 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 responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:D4018–99 (Reapproved 2008)
Standard Test Methods for
Properties of Continuous Filament Carbon and Graphite
Fiber Tows
This standard is issued under the fixed designation D4018; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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 E4 Practices for Force Verification of Testing Machines
E83 Practice for Verification and Classification of Exten-
1.1 These test methods cover the preparation and tensile
someter Systems
testing of resin-impregnated and consolidated test specimens
2.2 Other Document:
made from continuous filament carbon and graphite yarns,
CRC Handbook of Chemistry and Physics
rovings, and tows to determine their tensile properties.
1.2 These test methods also cover the determination of the
3. Terminology
density and mass per unit length of the yarn, roving, or tow to
3.1 Definition:
provide supplementary data for tensile property calculation.
3.1.1 sizing, n—agenerictermforcompoundswhich,when
1.3 These test methods include a procedure for sizing
applied to yarn or fabric, form a more or less continuous solid
removal to provide the preferred desized fiber samples for
film around the yarn and individual fibers.
density measurement. This procedure may also be used to
3.2 Definitions of Terms Specific to This Standard:
determine the weight percent sizing.
3.2.1 desized fiber, n—fiberwhichhashadasizingremoved
1.4 These test methods include a procedure for determining
from it.
the weight percent moisture adsorption of carbon or graphite
3.2.2 fiber, n—continuous filament carbon or graphite yarn,
fiber.
roving, or tow.
1.5 The values stated in SI units are to be regarded as the
3.2.3 sized fiber, n—a fiber with a sizing applied to it.
standard. The values in parentheses are for information only.
3.2.4 unsized fiber, n—fiber which has never had a sizing
1.6 This standard does not purport to address all of the
applied to it.
safety concerns, if any, associated with its use. It is the
3.3 Symbols
responsibility of the user of this standard to establish appro-
3.3.1 A—Unit conversion factor for tensile strength
priate safety and health practices and determine the applica-
3.3.2 B—Unit conversion factor for tensile modulus
bility of regulatory limitations prior to use.
3.3.3 E—fiber chord modulus
2. Referenced Documents 3.3.4 ´—Lower strain limit
l
3.3.5 ´ —Upper strain limit
u
2.1 ASTM Standards:
3.3.6 k —correction factor for density of size
D70 Test Method for Density of Semi-Solid Bituminous c
3.3.7 L—specimen length
Materials (Pycnometer Method)
3.3.8 MUL—the mass per unit length of the sized fiber
D1193 Specification for Reagent Water
3.3.9 MUL—the mass per unit length of the impregnated
I
D3800 Test Method for Density of High-Modulus Fibers
and consolidated fiber
D5550 Test Method for Specific Gravity of Soil Solids by
3.3.10 P—maximum load
Gas Pycnometer
3.3.11 P—tensile load at lower strain limit
l
3.3.12 P —tensile load at upper strain limit
u
These test methods are under the jurisdiction of ASTM Committee D30 on
3.3.13 r—density of the fiber
f
Composite Materials and are the direct responsibility of Subcommittee D30.03 on
3.3.14 r —density of the fiber with sizing
Constituent/Precursor Properties.
sf
Current edition approved Nov. 1, 2008. Published December 2008. Originally
3.3.15 RC—weight percent of resin (resin content)
approved in 1981. Last previous edition approved in 2004 as D4018–99(2004).
3.3.16 W —specimen mass
DOI: 10.1520/D4018-99R08.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on CRC Press Inc., Boca Raton, Ann Arbor, London, Tokyo, 73rd Edition,
the ASTM website. 1992–1993.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4018–99 (2008)
4. Summary of Test Methods resin-impregnated specimens. A third set is for tensile testing
the resin-impregnated and consolidated specimens. Optional
4.1 These test methods include procedures for determining
apparatus may be used for applying end tabs to the specimens
the tensile strength and modulus of a resin-impregnated and
and removing sizing.
consolidated carbon fiber tow.Also included are procedures to
measure the mass per unit length and density of the carbon
6.1.1 Resin Impregnation—The goal of the resin-
fiber and the resin content of the resin-impregnated and
impregnation apparatus is to apply and uniformly impregnate
consolidated specimens.
resin into the fiber. This is normally achieved by dipping the
4.2 MUL—The MUL of the fiber is determined by dividing
fiber into the resin and then working the wet fiber over rolls or
the mass of a sample of sized fiber by its length.
through a die, or both. While automated apparatuses are
4.3 Density—The density of the fiber is determined using
preferred for consistency, any apparatus which achieves uni-
Archimedes’ method or a pycnometer method. The recom-
form impregnation of 35 to 60% resin by weight and does not
mended specimen is desized or unsized fiber. The ideal
damage the fiber is acceptable.
immersion fluid is one that completely wets the specimen and
6.1.2 Consolidation—Anapparatustoholdtheimpregnated
provides minimum toxicity or environmental hazard.
specimens under tension during consolidation is required.
4.4 Resin Content—The resin content (weight percent) of
6.1.3 Optional End Tabs—An apparatus to cast resin end
the resin-impregnated and consolidated fiber is determined by
tabsonspecimensmaybeused.Apparatusestoapplyandalign
comparing the mass per unit length of the impregnated and
other forms of end tabs such as bonded on cardboard or metal
consolidated specimen to the fiber mass per unit length.
tabs may also be used.
4.5 Tensile Properties—The tensile strength and tensile
chord modulus of the fiber are determined by the tensile
6.1.4 Testing—Atensiletestingmachineandrecordermeet-
loading to failure of the resin-impregnated and consolidated
ing the requirements of Practices E4 at the maximum expected
fiber. The chord modulus is determined between defined strain
test load are required. The load recording device shall be
limits. The purpose of the impregnating resin is to provide the
coordinatedwiththeextensometerandstrainrecordertoassure
fiber,whenconsolidated,withsufficientmechanicalstrengthto
thatthecorrespondingloadandelongationofthespecimenare
produce an easily handled test specimen capable of sustaining
recorded at essentially the same time. The testing machine
uniform loading of the individual filaments in the specimen.
shall also have the following features:
The resin shall be compatible with the fiber and any size
6.1.4.1 Grips—Grips suitable for loading the tabbed or
applied to it. The strain capability of the consolidated resin
untabbedspecimenwithoutdamagingitarerequired.Forresin
shall be at least twice the strain capability of the fiber.
tabbed specimens a custom grip is generally required. For
untabbedorcardboardtabbedspecimenspneumaticorhydrau-
5. Significance and Use
licallypoweredgripsaretypicallyused.Differentgrippressure
5.1 The properties determined by these test methods are of
settings may be required for different fibers.
value in material specifications, qualifications, data base gen-
6.1.4.2 Jaws—Jaws compatible with the grips and capable
eration, certification, research, and development.
of holding a specimen without damaging it are required. For
5.2 These test methods are intended for the testing of fibers
untabbed specimens, flat jaws with rubber or other compliant
that have been specifically developed for use as reinforcing
materials bonded to the face are generally used. Sandpaper
agents in advanced composite structures. The test results of an
may also be placed on the grips to reduce slippage. For
impregnatedandconsolidatedfibershouldberepresentativeof
cardboard tabbed specimens serrated jaws are generally used.
the strength and modulus that are available in the material
Jaws should be inspected regularly and cleaned or repaired as
when used as intended. The performance of fibers in different
required.
resin systems can vary significantly so that correlations be-
tween results using these test methods and composite testing
6.1.4.3 Extensometer and Recorder—An extensometer and
may not always be obtained.
recording device in accordance with the requirements of
5.3 The reproducibility of test results is dependent upon
Practice E83 Class B-2 are required. The extensometer and
precisecontroloveralltestconditions.Resintype,contentand
recorder shall be coordinated with the tensile testing machine
distribution,curingprocess,filamentalignment,grippinginthe
so that the corresponding load and elongation of the specimen
testing machine, and alignment in the testing machine are of
are recorded at essentially the same time.
special importance.
6.1.4.4 Balance, Analytical—Accuracy of 60.0002 g for
5.4 The measured strengths of fibers are not unique quan-
mass per unit length, density, and resin or size content
titiesandtestresultsarestronglydependentonthetestmethods
determinations.
used. Therefore the test method described here will not
6.1.4.5 Balance, Laboratory—Accuracyof 60.1gformea-
necessarily give the same mean strengths or standard devia-
suring components of resin.
tions as those obtained from single filaments, dry fibers,
composite laminas, or composite laminates. 6.1.4.6 Length Measuring Devices—Devicestomeasurethe
length of impregnated and consolidated specimens and dry
6. Apparatus fiber to 62-mm accuracy are required.
6.1.4.7 Density Measuring Device—SeeTestMethodsD70,
6.1 Three sets of apparatus are required. One set is for resin
impregnation of the fiber. A second set is for curing the D3800,or D5550.
D4018–99 (2008)
6.1.4.8 Forced Air Oven—A forced air oven of sufficient conditions are the variables of interest. Conduct tensile testing
size and temperature capabilities to cure the impregnated fiber at 23 6 7°C and 50 6 20% relative humidity unless other
on the curing device. The temperature shall be controlled to conditions are the variables of interest.
610°C. 9.3 To determine moisture adsorption, dry a minimum of
five mass per unit-type specimens at 120 6 5°C for 24 h in a
7. Reagents and Materials circulating air oven. Cool samples in a desiccator. Remove
samples from desiccator one at a time and immediately weigh
7.1 Reagent Water—Unless otherwise indicated, references
them. Place samples in a humidity chamber and maintain at 23
to water shall be understood to mean reagent water as defined
62°Cand90%orgreaterrelativehumidityfor24h.Remove
by Type III of Specification D1193.
samples from the humidity chamber one at a time and weigh
7.2 Resin.
immediately.
7.3 Commercial Grade Solvent, (optional) for resin dilu-
9.4 If all specimens are conditioned for 24 h and mass per
tion.
unit length and density testing are performed at 23 6 2°C and
7.4 Hardener or Catalyst.
50 6 10% relative humidity, then no testing for moisture
7.5 Surfactant (optional).
adsorption is required.
9.5 Moisture adsorption testing is only required once annu-
8. Test Specimens
ally for a standard product.
8.1 Mass per Unit Length Specimen—The specimen to
measuremassperunitlengthisa1-mminimumlengthoffiber 10. Specimen Preparation
in the form in which it is intended to be used. Test one
10.1 Mass per Unit Length—No preparation is required.
specimen per sample. Coil the specimen into a usable form for
Thesampleistakenfromapackageofmaterialasitisintended
testing.Careisrequiredtonotdamageandlosefilamentsfrom
to be used.
the specimen.
10.2 Density—The preferred density specimen is a desized
8.2 Density Specimen—Density specimens may be sized,
or unsized fiber. This eliminates any need to correct for the
unsized, or desized material. Unsized or desized samples are
densityofthesizing.Thesizingmayberemovedusingsolvent
preferred. Test one specimen per sample. A 1-m minimum
extraction, pyrolysis, or other means. An example method is
length is required forTest Method D3800. For methods inTest
described inAppendix X1.An unsized sample of a sized fiber
Methods D70 and D5550, a suitable volume to fill the
would have to be collected during the production of the fiber
container is recommended. Coil the specimen into a usable
and is therefore not recommended.
form for testing. Care is required to not damage and lose
10.3 Tensile Test—The tensile test specimen must be im-
filaments from the specimen.
pregnated with resin and consolidated before testing.
8.3 Tensile Test Specimen—The tensile specimen shall be a
10.3.1 Resin Preparation—Any resin that meets the re-
tabbed or untabbed resin-impregnated and consolidated fiber.
quirementsof4.5maybeused.Theresinwhencombinedwith
Tabbed specimens shall have a 150-mm gage length between
the fiber shall produce a composite (reinforcement/matrix)
the tabs. Untabbed specimens shall be of sufficient length to
failure.Aresingenerallyfoundsatisfactoryisacombinationof
allow a 150-mm gage length between the grips when they are
bisphenolA(orbisphenolF)epoxyanddiethyltoluenediamine
tested.Sampleswith3000filamentsorlessmaybetestedusing
in the weight ratio of 3.9:1.Asolvent that lowers the viscosity
specimens of more than one fiber bundle to facilitate handling.
of a resin mixture or softens the sizing, or both, may be
Combine the bundles before resin impregnation and count the
selectedforusewiththeresin.Theamountandtypeofsolvent
test results as one specimen. Test a minimum of four test
used will vary with the product and apparatus used for
specimens per sample. Separate test specimens for modulus
impregnation. Prepare and store the resin in accordance with
and strength determination are permitted; however, four speci-
the manufacturer’s instructions.
mens for each test are required. Specimens that are fuzzy,
10.3.2 Fiber Impregnation—The resin shall be maintained
curved, not uniform in cross section, have broken filaments,
withinasuitableviscosityortemperaturerangethroughoutthe
resin lumps, or other observable defects should be rejected
impregnation process that assures reproducible specimen con-
unless they are representative of the material being tested.
stituency and quality. An automated impregnation device is
recommended but not required. The objective of impregnation
9. Conditioning
is a uniform, well-collimated strand with adequate resin,
9.1 Fibersthatadsorblessthan0.5%mois
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