ASTM D3171-99(2004)
(Test Method)Standard Test Methods for Constituent Content of Composite Materials
Standard Test Methods for Constituent Content of Composite Materials
SCOPE
1.1 These test methods determine the constituent content of composite materials by one of two approaches. Method I physically removes the matrix by digestion or ignition by one of seven procedures, leaving the reinforcement essentially unaffected and thus allowing calculation of reinforcement or matrix content (by weight or volume) as well as percent void volume. Method II, applicable only to laminate materials of known fiber areal weight, calculates reinforcement or matrix content (by weight or volume) based on the measured thickness of the laminate. Method II is not applicable to the measurement of void volume.
1.1.1 These test methods are primarily intended for two-part composite material systems. However, special provisions can be made to extend these test methods to filled material systems with more than two constituents, though not all test results can be determined in every case.
1.1.2 The procedures contained within have been designed to be particularly effective for certain classes of polymer or metal matrices. The suggested applications are discussed in Section , as well as at the start of each procedure.
1.1.3 Method I assumes that the reinforcement is essentially unaffected by the digestion or ignition medium. A procedure for correction of the results for minor changes in the reinforcement is included. Procedures A through F are based on chemical removal of the matrix while Procedure G removes the matrix by igniting the matrix in a furnace.
1.1.4 Method II assumes that the fiber areal weight of the reinforcement material form is known or controlled to an acceptable tolerance. The presence of voids is not measured. Eqn. 1 assume zero void content to perform the calculation.
1.2 The SI units shown are considered standard.
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. See Section 9 for additional information.
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Designation:D3171–99 (Reapproved 2004)
Standard Test Methods for
Constituent Content of Composite Materials
This standard is issued under the fixed designation D 3171; 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 bility of regulatory limitations prior to use. See Section 9 for
additional information.
1.1 These test methods determine the constituent content of
composite materials by one of two approaches. Method I
2. Referenced Documents
physically removes the matrix by digestion or ignition by one
2.1 ASTM Standards:
of seven procedures, leaving the reinforcement essentially
D 792 TestMethodsforDensityandSpecificGravity(Rela-
unaffected and thus allowing calculation of reinforcement or
tive Density) of Plastics by Displacement
matrix content (by weight or volume) as well as percent void
D 883 Terminology Relating to Plastics
volume. Method II, applicable only to laminate materials of
D 1505 Test Method for Density of Plastics by the Density
known fiber areal weight, calculates reinforcement or matrix
Gradient Technique
content(byweightorvolume)basedonthemeasuredthickness
D 3878 Terminology of High-Modulus Reinforcing Fibers
ofthelaminate.MethodIIisnotapplicabletothemeasurement
and Their Composites
of void volume.
D 5229/D 5229M Test Method for Moisture Absorption
1.1.1 Thesetestmethodsareprimarilyintendedfortwo-part
Properties and Equilibrium Conditioning of Polymer Ma-
composite material systems. However, special provisions can
trix Composite Materials
be made to extend these test methods to filled material systems
E 12 Terminology Relating to Density and Specific Gravity
with more than two constituents, though not all test results can
of Solids, Liquids, and Gases
be determined in every case.
E 171 Specification for Standard Atmospheres for Condi-
1.1.2 The procedures contained within have been designed
tioning and Testing Flexible Barrier Materials
to be particularly effective for certain classes of polymer or
E 177 Practice for Use of Terms Precision and Bias in
metal matrices. The suggested applications are discussed in
ASTM Test Methods
Section 4, as well as at the start of each procedure.
E 1309 Guide for the Identification of Fiber-Reinforced
1.1.3 Method I assumes that the reinforcement is essentially
Polymer-Matrix Composite Materials in Computerized
unaffected by the digestion or ignition medium. A procedure
Material Property Databases
for correction of the results for minor changes in the reinforce-
ment is included. Procedures A through F are based on
3. Terminology
chemicalremovalofthematrixwhileProcedureGremovesthe
3.1 Definitions—TerminologyD 3878definestermsrelating
matrix by igniting the matrix in a furnace.
to composite materials. Terminology D 883 defines terms
1.1.4 Method II assumes that the fiber areal weight of the
relating to plastics. Terminology E 12 defines terms relating to
reinforcement material form is known or controlled to an
specific gravity. Practice E 177 defines terms relating to
acceptable tolerance. The presence of voids is not measured.
statistics.Intheeventofaconflictbetweenterms,Terminology
Eq 9 and 10 assume zero void content to perform the
D 3878 shall have precedence over other documents.
calculation.
3.1.1 fiber content, n—the amount of fiber present in a
1.2 The SI units shown are considered standard.
composite or prepreg expressed either as percent by weight or
1.3 This standard does not purport to address all of the
percent by volume.This is sometimes stated as a fraction. If no
safety concerns, if any, associated with its use. It is the
fillers exist, this is equivalent to reinforcement content.
responsibility of the user of this standard to establish appro-
D3878
priate safety and health practices and determine the applica-
1 2
These test methods are under the jurisdiction of ASTM Committee D30 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Composite Materials and are the direct responsibility of Subcommittee D30.04 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Lamina and Laminate Test Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2004. Published November 2004. Originally the ASTM website.
approved in 1973. Last previous edition approved in 1999 as D 3171 – 99. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3171–99 (2004)
3.1.2 matrix content, n—the amount of matrix present in a change is sufficiently reproducible under the conditions of the
composite or prepreg expressed either as percent by weight or test and has the same value for the reinforcement or matrix
percentbyvolume.Forpolymermatrixcompositesthisisresin alone as for the constituents in the composite.
content. D3878 4.1.1.1 Procedure A, for matrices such as epoxy resin, steel,
3.1.3 reinforcement content, n—the amount of nonmatrix copper, or others digestible by concentrated nitric acid.
material (fiber and filler) in a composite or prepreg expressed
NOTE 1—Many reinforcements are attacked by nitric acid. If reinforce-
either as percent by weight or percent by volume. D3878
mentisattacked,analternativemethodisrecommended,dependingonthe
3.1.4 resin content, n—See matrix content. D3878
matrix. See Annex A1.
3.1.5 void volume, n—the volume in the specimen without
4.1.1.2 Procedure B, for matrices such as epoxy, phenolic,
mass, that is identified as neither matrix nor reinforcement.
polyamide, or thermoplastic resin, or others digestible by an
D3878
aqueous mixture of sulfuric acid and hydrogen peroxide. See
3.2 Definitions of Terms Specific to This Standard:
Annex A2.
23°C
3.2.1 density, r —the weight per unit volume measured
4.1.1.3 Procedure C, for matrices such as epoxy resin and
in air, of the impermeable portion of a material at 23°C.
othersdigestiblebyamixtureofethyleneglycolandpotassium
3.2.1.1 Discussion—The definition of specific gravity and
hydroxide. See Annex A3.
density are essentially equivalent to the definitions of apparent
NOTE 2—Procedure C is especially applicable to anhydride-cured
specific gravity and apparent density in Terminology E 12,
epoxy systems containing aramid or carbon reinforcement.
because no correction is made for buoyancy of the material in
air. However, this difference is insignificant for most engineer-
4.1.1.4 Procedure D, for matrices such as aluminum, brass,
ing purposes.
or others digestible by sodium hydroxide solution. See Annex
23°C
3.2.2 specific gravity, SG —the ratio of the weight in air
A4.
of a unit volume of the impermeable portion of a material at
4.1.1.5 Procedure E, for matrices such as steel, titanium,
23°C referenced to the standard unit volume weight of water at
copper, aluminum, or others digestible by hydrochloric acid.
23°C.
See Annex A5.
3.3 Symbols:
4.1.1.6 Procedure F, a version of Procedure A for
microwave-aided heating. See Annex A6.
4.1.1.7 Procedure G, for reinforcements such as glass, or
A = area of the specimen.
ceramic that are not affected by high-temperature environ-
A = calculated mass of one layer of reinforcement/unit
r
ments, or reinforcements such as carbon where temperature is
area.
adequately controlled so that reinforcement does not char. See
r = density of the composite specimen.
c
Annex A7.
r = density of the cured matrix.
m
4.2 Test Method II—The thickness of a relatively flat panel
r = density of the reinforcement or fiber.
r
made with reinforcement of known and consistent areal weight
h = thickness of the specimen.
is measured. By the thickness of the panel, the reinforcement
M = mass of the dry crucible or sintered glass filter.
c
and matrix content is calculated.
M = mass of the dry crucible or sintered glass filter with
cr
reinforcement residue.
5. Significance and Use
M = initial mass of specimen before digestion or com-
i
5.1 A constituent content of a composite material must be
bustion.
known in order to analytically model the material properties
M = final mass of specimen after digestion or combus-
f
tion. (mechanical, physical, thermal, or electrical) of the composite
V = volume percent of matrix in specimen. which are affected by the reinforcement or matrix. Also,
m
V = volume percent of reinforcement in the specimen.
knowledge of the constituent content is required for evaluation
r
V = void volume percent in the specimen.
of the quality of a fabricated material and the processes used
v
W = weight percent of matrix in the specimen.
m during fabrication.
W = weight percent of reinforcement in the specimen.
r
5.2 The void volume of a composite material may signifi-
cantly affect some of its mechanical properties. Higher void
4. Summary of Test Method
volumes usually mean lower fatigue resistance, greater suscep-
4.1 Test Method I—The matrix portion of a material speci-
tibility to moisture penetration and weathering, and increased
men of known mass is removed in a hot liquid medium (for
variation or scatter in strength properties. Knowledge of the
dissolution) or furnace (for combustion). When dissolving in a
void volume of a composite material is desirable as an
hot liquid medium,the remaining residue, containing the rein-
indication of the quality of a composite.
forcement,isthenfiltered,washed,dried,cooled,andweighed.
5.3 Reinforcement content may be used to normalize me-
The weight percent of the reinforcement is calculated, and
chanical properties affected by amount of reinforcement in the
from this value, and if densities of both the composite and the
coupon.
reinforcement are known, the volume percent is calculated.An
6. Interferences
additional calculation for void volume may be made if the
density of the matrix is known or determined. 6.1 Density of Constituents—Calculation of the void vol-
4.1.1 Acorrectionforweightchangeofthereinforcementor ume assumes that reinforcement density and matrix density
retention of the matrix may be made (13.3 and 13.4), if this obtained on a lot or material basis are held in the laminate
D3171–99 (2004)
sample. There is a normal variation in reinforcement and thickness of the material at a point. The micrometer thickness
matrix densities that is dependent on the constituent material. measure is dependent on (1) variation in thickness of the panel,
This assumption used by the void calculation equations is (2)typeanddiameterofthicknessmeasuringdevice,(3)ability
typically minor, changing the void calculation by less than to hold panel perpendicular to the measurement device, and (4)
0.2 %. One indication of this variation is the possibility of sensitivity of the measurement device.
obtaining a negative void volume in low-void volume compos- 6.6.1 Ball micrometer geometry tends to give a thickness
ites. If procedural errors can be ruled out, then it is reasonable measure for Test Method II that more closely approximates
to believe that constituent density variation is responsible. fiber volume if there is a rough surface texture than a flat-faced
Negative void content is a physical impossibility, but a micrometer that tends to overstate laminate thickness. For
possibility in these calculations. It is useful to report negative some material forms, such as open weaves, the ball geometry
void contents to assess if constituent density values are is not practical, so that a flat face micrometer is recommended.
incorrect or within a typical range of material variation. The
7. Apparatus
negative void value then sets an upper bound on error of this
test method for any material. 7.1 General Requirements:
6.2 Coupon Size—Ability to estimate void content is also
7.1.1 Thermal Shock—Laboratory equipment, which is sub-
determined by coupon size and limitations of measuring
jected to nonambient temperatures (hot or cold), shall be of
apparatus. For example, with just limitations of the analytical
tempered glass or polytetrafluoroethylene (PTFE) materials.
balance (accurate to 0.2 mg), a coupon of 0.2 g with a void
7.1.2 Post-Test Elemental Analysis—If a post-test elemental
volume of 1.0 % would have an uncertainty of 10 % (reported
analysis of the reinforcement residue is to be performed,
void volume in the range of 0.9 to 1.1 %) on the void volume
laboratory equipment contacting the specimen shall be con-
calculation as a result of possible balance error. A 1-g sample
structed of PTFE, and specimen cutting performed only by
would have an uncertainty of 2 % in the void volume calcula-
diamond-tipped tools.
tion (reported void volume in the range of 0.98 to 1.02 %) 7.2 General Usage:
because of possible balance error for the same 1.0 % void
7.2.1 Analytical Balance—The analytical balance shall be
volume. capable of reading to within 60.1 mg.
4,5
6.3 Error in Previous Measures —Ability to estimate void
7.2.2 Laboratory Desiccator.
content is also determined by the accuracy of previous mea- 7.3 Test Method I:
sures. Density measures of constituents and laminate have
7.3.1 Heating Equipment:
some limitations. Good measures of these properties should 7.3.1.1 Constant Heat Source—Heating mantle, hot plate,
have an uncertainty of less than 0.0005 g/mL. For a typical
or controlled temperature bath, capable of heating material to
carbon/epoxylaminate,uncertaintyinthevoidvolumebecause the required temperature for the particular digestion medium
of the limitation of the constituent density measurement would
and shall be capable of maintaining the temperature to 610°C.
be approximately 1 %. 7.3.1.2 Microwave,capableofmaintainingaconstantpower
6.4 Mass Change of Reinforcement—Fibers may lose mass
output. The microwave setup shall include an overpressure
by any of the techniques in Test Method I. This may be
fail-safe device. Used exclusively for Procedure F (see Annex
investigated by subjecting the reinforcement without matrix to
A6).
the test conditions of the composite. Once the technique is
7.3.1.3 Drying Oven, air circulating, capable of maintaining
established for a material, no significant changes are expected
a temperature of 100 6 3°C or other target temperature within
between samples unless the product or test conditions vary
63°C.
significantly.
7.3.1.4 Muffle Furnace, capable of maintaining a tempera-
6.5 Residual Matrix Retained—Matrix may be retained by
ture where the polymer matrix is removed, but the reinforce-
any of the techniques of Test Method I. This may be investi- ment is unaffected.
...
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