ASTM D4018-99
(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
SCOPE
1.1 These test methods cover the preparation and tensile testing of resin-impregnated and cured 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 problems, 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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Designation: D 4018 – 99
Standard Test Methods for
Properties of Continuous Filament Carbon and Graphite
Fiber Tows
This standard is issued under the fixed designation D 4018; 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 3800 Test Method for Density of High-Modulus Fibers
D 3878 Terminology of High-Modulus Reinforcing Fibers
1.1 These test methods cover the preparation and tensile
and Their Composites
testing of resin-impregnated and consolidated test specimens
D 5550 Test Methods for Soil Solids—Specific Gravity by
made from continuous filament carbon and graphite yarns,
Gas Pycnometer Test
rovings, and tows to determine their tensile properties.
E 4 Practices for Force Verification of Testing Machines
1.2 These test methods also cover the determination of the
E 6 Terminology Relating to Methods of Mechanical Test-
density and mass per unit length of the yarn, roving, or tow to
ing
provide supplementary data for tensile property calculation.
E 83 Practice for Verification and Classification of Exten-
1.3 These test methods include a procedure for sizing
someters
removal to provide the preferred desized fiber samples for
E 100 Specification for ASTM Hydrometers
density measurement. This procedure may also be used to
2.2 Other Document:
determine the weight percent sizing.
CRC Handbook of Chemistry and Physics
1.4 These test methods include a procedure for determining
the weight percent moisture adsorption of carbon or graphite
3. Terminology
fiber.
3.1 Definition:
1.5 The values stated in SI units are to be regarded as the
3.1.1 sizing, n—a generic term for compounds which, when
standard. The values in parentheses are for information only.
applied to yarn or fabric, form a more or less continuous solid
1.6 This standard does not purport to address all of the
film around the yarn and individual fibers.
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 desized fiber, n—fiber which has had a sizing removed
priate safety and health practices and determine the applica-
from it.
bility of regulatory limitations prior to use.
3.2.2 fiber, n—continuous filament carbon or graphite yarn,
2. Referenced Documents roving, or tow.
3.2.3 sized fiber, n—a fiber with a sizing applied to it.
2.1 ASTM Standards:
3.2.4 unsized fiber, n—fiber which has never had a sizing
D 70 Test Method for Specific Gravity/Density of Semi-
applied to it.
solid Bituminous Materials/Asphalt Cement/Soft Tar
2 3.3 Symbols
Pitches by Pycnometer Test
3.3.1 A—Unit conversion factor for tensile strength
D 123 Terminology Relating to Textiles
3.3.2 B—Unit conversion factor for tensile modulus
D 891 Test Methods for Specific Gravity, Apparent, of
3.3.3 E—fiber chord modulus
Liquid Industrial Chemicals
3.3.4 e —Lower strain limit
l
D 1193 Specification for Reagent Water
3.3.5 e —Upper strain limit
u
3.3.6 k —correction factor for density of size
c
These test methods are under the jurisdiction of ASTM Committee D-30 on
Composite Materials and are the direct responsibility of Subcommittee D30.03 on
Constitutuent/Precursor Properties.
Current edition approved Oct. 10, 1999. Published February 2000. Originally Annual Book of ASTM Standards, Vol 15.03.
published as D 4018 – 81. Last previous edition D 4018 – 93. Annual Book of ASTM Standards, Vol 04.09.
2 8
Annual Book of ASTM Standards, Vol 04.03 Annual Book of ASTM Standards, Vol 03.01.
3 9
Annual Book of ASTM Standards, Vol 07.01. Annual Book of ASTM Standards, Vol 14.03.
4 10
Annual Book of ASTM Standards, Vol 15.05. CRC Press Inc., Boca Raton, Ann Arbor, London, Tokyo, 73rd Edition,
Annual Book of ASTM Standards, Vol 11.01. 1992–1993.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4018
3.3.7 L—specimen length distribution, curing process, filament alignment, gripping in the
testing machine, and alignment in the testing machine are of
3.3.8 MUL—the mass per unit length of the sized fiber
special importance.
3.3.9 MUL —the mass per unit length of the impregnated
I
5.4 The measured strengths of fibers are not unique quan-
and consolidated fiber
tities and test results are strongly dependent on the test methods
3.3.10 P—maximum load
used. Therefore the test method described here will not
3.3.11 P —tensile load at lower strain limit
l
necessarily give the same mean strengths or standard devia-
3.3.12 P —tensile load at upper strain limit
u
tions as those obtained from single filaments, dry fibers,
3.3.13 r —density of the fiber
f
composite laminas, or composite laminates.
3.3.14 r —density of the fiber with sizing
sf
3.3.15 RC—weight percent of resin (resin content)
6. Apparatus
3.3.16 W —specimen mass
6.1 Three sets of apparatus are required. One set is for resin
impregnation of the fiber. A second set is for curing the
4. Summary of Test Methods
resin-impregnated specimens. A third set is for tensile testing
4.1 These test methods include procedures for determining
the resin-impregnated and consolidated specimens. Optional
the tensile strength and modulus of a resin-impregnated and
apparatus may be used for applying end tabs to the specimens
consolidated carbon fiber tow. Also included are procedures to
and removing sizing.
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—An apparatus to hold the impregnated
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
tabs on specimens may be used. Apparatuses to apply and align
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
6.1.4 Testing—A tensile testing machine and recorder meet-
chord modulus of the fiber are determined by the tensile
ing the requirements of Practices E 4 at the maximum expected
loading to failure of the resin-impregnated and consolidated
test load are required. The load recording device shall be
fiber. The chord modulus is determined between defined strain
coordinated with the extensometer and strain recorder to assure
limits. The purpose of the impregnating resin is to provide the
that the corresponding load and elongation of the specimen are
fiber, when consolidated, with sufficient mechanical strength to
recorded at essentially the same time. The testing machine
produce an easily handled test specimen capable of sustaining
shall also have the following features:
uniform loading of the individual filaments in the specimen.
6.1.4.1 Grips—Grips suitable for loading the tabbed or
The resin shall be compatible with the fiber and any size
untabbed specimen without damaging it are required. For resin
applied to it. The strain capability of the consolidated resin
tabbed specimens a custom grip is generally required. For
shall be at least twice the strain capability of the fiber.
untabbed or cardboard tabbed specimens pneumatic or hydrau-
lically powered grips are typically used. Different grip pressure
5. Significance and Use
settings may be required for different fibers.
5.1 The properties determined by these test methods are of
6.1.4.2 Jaws—Jaws compatible with the grips and capable
value in material specifications, qualifications, data base gen-
of holding a specimen without damaging it are required. For
eration, certification, research, and development.
untabbed specimens, flat jaws with rubber or other compliant
5.2 These test methods are intended for the testing of fibers
materials bonded to the face are generally used. Sandpaper
that have been specifically developed for use as reinforcing may also be placed on the grips to reduce slippage. For
agents in advanced composite structures. The test results of an
cardboard tabbed specimens serrated jaws are generally used.
impregnated and consolidated fiber should be representative of Jaws should be inspected regularly and cleaned or repaired as
the strength and modulus that are available in the material
required.
when used as intended. The performance of fibers in different
6.1.4.3 Extensometer and Recorder—An extensometer and
resin systems can vary significantly so that correlations be-
recording device in accordance with the requirements of
tween results using these test methods and composite testing
Practice E 83 Class B-2 are required. The extensometer and
may not always be obtained.
recorder shall be coordinated with the tensile testing machine
5.3 The reproducibility of test results is dependent upon so that the corresponding load and elongation of the specimen
precise control over all test conditions. Resin type, content and are recorded at essentially the same time.
D 4018
6.1.4.4 Balance, Analytical—Accuracy of 60.0002 g for conditioning before testing. Conduct mass per unit length,
mass per unit length, density, and resin or size content density, and tensile testing for these materials at 23 6 7°C and
determinations. 50 6 20 % relative humidity unless other conditions are the
6.1.4.5 Balance, Laboratory—Accuracy of 60.1 g for mea- variables of interest.
suring components of resin.
9.2 Condition fibers that adsorb more than 0.5 % moisture
6.1.4.6 Length Measuring Devices—Devices to measure the by weight (at 23 6 2°C and 90 % or greater relative humidity)
length of impregnated and consolidated specimens and dry
for a minimum of 24 h at 23 6 2°C and 50 6 10 % relative
fiber to 62-mm accuracy are required. humidity. Conduct mass per unit length and density testing at
6.1.4.7 Density Measuring Device—See Test Methods
23 6 2°C and 50 6 10 % relative humidity unless other
D 70, D 3800, or D 5550. conditions are the variables of interest. Conduct tensile testing
6.1.4.8 Forced Air Oven—A forced air oven of sufficient
at 23 6 7°C and 50 6 20 % relative humidity unless other
size and temperature capabilities to cure the impregnated fiber conditions are the variables of interest.
on the curing device. The temperature shall be controlled to
9.3 To determine moisture adsorption, dry a minimum of
610°C.
five mass per unit-type specimens at 120 6 5°C for 24 h in a
circulating air oven. Cool samples in a desiccator. Remove
7. Reagents and Materials
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
6 2°C and 90 % or greater relative humidity for 24 h. Remove
by Type III of Specification D 1193.
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
measure mass per unit length is a 1-m minimum length of fiber
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
The sample is taken from a package of material as it is intended
testing. Care is required to not damage and lose filaments from
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
density of the sizing. The sizing may be removed using solvent
preferred. Test one specimen per sample. A 1–m minimum
extraction, pyrolysis, or other means. An example method is
length is required for Test Method D 3800. For methods in Test
described in Appendix X1. An unsized sample of a sized fiber
Methods D 70 and D 5550, 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.
quirements of 4.5 may be used. The resin when combined with
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. A resin generally found satisfactory is a combination of
allow a 150-mm gage length between the grips when they are
bisphenol A (or bisphenol F) epoxy and diethyltoluene diamine
tested. Samples with 3000 filaments or less may be tested using
in the weight ratio of 3.9:1. A solvent that lowers the viscosity
specimens of more than one fiber bundle to facilitate handli
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