ASTM C613/C613M-97(2003)e1
(Test Method)Standard Test Method for Constituent Content of Composite Prepreg by Soxhlet Extraction
Standard Test Method for Constituent Content of Composite Prepreg by Soxhlet Extraction
SIGNIFICANCE AND USE
The prepreg volatiles content, matrix content, reinforcement content, and filler content of composite prepreg materials are used to control material manufacture and subsequent fabrication processes, and are key parameters in the specification and production of such materials, as well as in the fabrication of products made with such materials.
The extraction products resulting from this test method (the extract, the residue, or both) can be analyzed to assess chemical composition and degree of purity.
SCOPE
1.1 This test method covers a Soxhlet extraction procedure to determine the matrix content, reinforcement content, and filler content of composite material prepreg. Volatiles content, if appropriate, and required, is determined by means of Test Method D 3530/D 3530M.
1.1.1 The reinforcement and filler must be substantially insoluble in the selected extraction reagent and any filler must be capable of being separated from the reinforcement by filtering the extraction residue.
1.1.2 Reinforcement and filler content test results are total reinforcement content and total filler content; hybrid material systems with more than one type of either reinforcement or filler cannot be distinguished.
1.2 This test method focuses on thermosetting matrix material systems for which the matrix may be extracted by an organic solvent. However, other, unspecified, reagents may be used with this test method to extract other matrix material types for the same purposes.
1.3 Alternate techniques for determining matrix and reinforcement content include Test Methods D 3171 (matrix digestion), D 2584 (matrix burn-off/ignition), and D 3529/D 3529M (matrix dissolution). Test Method D 2584 is preferred for reinforcement materials, such as glass, quartz, or silica, that are unaffected by high-temperature environments.
1.4 The values stated in SI units are to be regarded as standard.
1.5 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. Specific precautionary statements are given in Section 9 and 7.2.3 and 8.2.1.
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Designation:C613/C613M–97 (Reapproved 2003)
Standard Test Method for
Constituent Content of Composite Prepreg by Soxhlet
Extraction
ThisstandardisissuedunderthefixeddesignationC613/C613M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 (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.
e NOTE—Warning/precaution notes were moved into the text editorially in October 2003.
1. Scope 2. Referenced Documents
1.1 This test method covers a Soxhlet extraction procedure 2.1 ASTM Standards:
to determine the matrix content, reinforcement content, and D883 Terminology Relating to Plastics
filler content of composite material prepreg. Volatiles content, D2584 Test Method for Ignition Loss of Cured Reinforced
if appropriate, and required, is determined by means of Test Resins
Method D3530/D3530M. D3171 Test Method for Constituent Content of Composite
1.1.1 The reinforcement and filler must be substantially Materials
insoluble in the selected extraction reagent and any filler must D3529/D3529M Test Method for Matrix Solids Content
be capable of being separated from the reinforcement by and Matrix Content of Composite Prepreg
filtering the extraction residue. D3530/D3530M Test Method for Volatiles Content of
1.1.2 Reinforcement and filler content test results are total Composite Material Prepreg
reinforcement content and total filler content; hybrid material D3878 Terminology of Composite Materials
systems with more than one type of either reinforcement or E122 Practice for Calculating Sample Size to Estimate,
filler cannot be distinguished. With Specified Tolerable Error, theAverage for Character-
1.2 This test method focuses on thermosetting matrix ma- istic of a Lot or Process
terial systems for which the matrix may be extracted by an E177 Practice for Use of Terms Precision and Bias in
organic solvent. However, other, unspecified, reagents may be ASTM Test Methods
usedwiththistestmethodtoextractothermatrixmaterialtypes E456 Terminology Relating to Quality and Statistics
for the same purposes. E1309 Guide for Identification of Composite Materials in
1.3 Alternate techniques for determining matrix and rein- Computerized Material Property Databases
forcementcontentincludeTestMethodsD3171(matrixdiges- E 1471 Guide for Identification of Fiber-Reinforced
tion), D2584 (matrix burn-off/ignition), and D3529/D3529M Polymer-Matrix Composite Materials in Databases
(matrix dissolution). Test Method D2584 is preferred for 2.2 NFPA Standard:
reinforcementmaterials,suchasglass,quartz,orsilica,thatare NFPA 86 Standard for Ovens and Furnaces
unaffected by high-temperature environments.
3. Terminology
1.4 The values stated in SI units are to be regarded as
standard. 3.1 Definitions—TerminologyD3878definestermsrelating
to composite materials. Terminology D883 defines terms
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the relating to plastics. Terminology E456 and Practice E177
define terms relating to statistics. In the event of a conflict
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- between terms, Terminology D3878 shall have precedence
over the other documents.
bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in Section 9 and 7.2.3 and 8.2.1.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D30 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Composite Materials and is the direct responsibility of Subcommittee D30.03 on Standards volume information, refer to the standard’s Document Summary page on
Constituent/Precursor Properties. the ASTM website.
Current edition approved Oct. 1, 2003. Published October 2003. Originally Available from National Fire Protection Association (NFPA), 1 Batterymarch
approved in 1967. Last previous edition approved in 1997 as C613–97. Park, Quincy, MA 02269-9101.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C613/C613M–97 (2003)
3.1.1 matrix content, n—the amount of matrix present in a 3.3.4 CV—coefficient of variation statistic of a sample
composite or prepreg expressed either as percent by weight or population for a given property.
percentbyvolume.Forpolymermatrixcompositesthisisresin 3.3.5 M —additional mass of filler in the test specimen.
a
content. D 3878 3.3.6 M —mass of the test specimen extraction residue.
e
3.1.2 prepreg, n—the admixture of fibrous reinforcement 3.3.7 M—initial mass of the test specimen.
i
andpolymericmatrixusedtofabricatecompositematerials.Its 3.3.8 M —mass of reinforcement in the test specimen.
r
form may be sheet, tape, or tow. For thermosetting matrices it 3.3.9 n—number of replicates in the sample population.
has been partially cured to a controlled viscosity called “B 3.3.10 s —standard deviation statistic of a sample popu-
n−1
stage”. D 3878 lation for a given property.
3.1.3 resin content, n—see matrix content. D 3878 3.3.11 W—weight percent of filler in prepreg.
f
3.1.4 sample, n—a small part or portion of a material or 3.3.12 W —weight percent of matrix in prepreg.
m
product intended to be representative of the whole. D 883 3.3.13 W —weight percent of reinforcement in prepreg.
r
3.1.5 test result, n—the value obtained for a given property 3.3.14 x—test result for an individual test specimen from
i
from one test unit. the sample population for a given property.
3.1.5.1 Discussion—A test result may be a single observa- 3.3.15 x¯—averagevalueofasamplepopulationforagiven
tionoracombinationofanumberofobservationswhentwoor property.
more test specimens are measured for each test.
4. Summary of Test Method
3.1.6 test specimen, n—a test unit or portion of a test unit
upon which a single or multiple observation is to be made.
4.1 The exposed surface area of the prepreg material test
3.1.7 test unit, n—a unit or portion of a material that is
specimenisincreasedbycuttingthetestspecimenintosmaller
sufficienttoobtainatestresult(s)forthepropertyorproperties
pieces. The test specimen is weighed and the matrix material
to be measured.
removedbymeansofSoxhletextraction.Theextractedresidue
3.1.7.1 Discussion—A test unit may be a subunit of a
is dried and weighed. If a filler is present in the residue, in
primary (first stage) sampling unit or it may be a subunit of a
addition to reinforcement, the two components are separated
composite of primary sampling units or of increments from
by filtering the residue. From mass measurements of the initial
these primary sampling units.
test specimen, and of the residue taken at various stages in the
3.2 Definitions of Terms Specific to This Standard:
process, the matrix content, reinforcement content, and filler
3.2.1 dry resin content, n—prepreg resin content calculated
content are calculated and reported in weight percent.
by subtracting the average mass loss due to volatiles from the
4.1.1 Soxhlet Process—While described in detail in com-
initial test specimen mass.
mon quantitative chemical analysis textbooks, the Soxhlet
3.2.2 filler content, n—the amount of filler present in a
process is summarized as follows. The test specimen is loaded
prepreg or composite expressed either as percent by weight or
into a filtering extraction thimble, which is placed into the
percent by volume.
extraction chamber of a Soxhlet extraction assembly (see Fig.
3.2.2.1 Discussion—Inthistestmethodthereinforcementis
1) containing an appropriate extraction reagent. The porous
separated from the remainder of the material, which includes
thimble allows the liquid extraction reagent to pass while
the matrix and the filler. If the filler is not then separated from
retaining the test specimen. Freshly distilled liquid reagent
the matrix to determine the proportion of each, then the filler
entersfromthetopoftheextractionchamber,fillingituntilthe
content is included in the matrix content.
liquid reaches the highest level of the reagent-return tube. At
3.2.3 reinforcement content, n—the amount of reinforce-
this moment the tube operates as a siphon, draining the
ment present in a composite or prepreg expressed either as
extraction chamber completely as it returns the liquid reagent
percent by weight or percent by volume. This is sometimes
andanyextractedmaterialtoareservoirbeneaththeextraction
stated as a fraction, that is, reinforcement volume fraction.
chamber. The heated reservoir boils the reagent, the vapor of
3.2.4 replicate, n—a test specimen tested under nominally
identical conditions as other test specimens from the same
sample.
3.2.5 volatilescontent,n—theamountofvolatilespresentin
a prepreg expressed as percent by weight.
3.2.6 wet resin content, n—prepreg resin content deter-
mined by considering volatiles as part of the resin mass.
3.3 Symbols:
3.3.1 A—initial mass of dry reinforcement during a reagent
exposure evaluation.
3.3.2 B—final mass of dry reinforcement during a reagent
exposure evaluation.
3.3.3 c—percent reinforcement mass change due to reagent
exposure.
See Form and Style for ASTM Standards. FIG. 1 Schematic of Soxhlet Extraction Apparatus
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C613/C613M–97 (2003)
which is led to a condenser placed above the extraction 7. Apparatus
chamber. The distilled condensate then drips down into the
7.1 General Requirements:
thimble,startingonceagaintheprocessoffillingtheextraction
7.1.1 Container Volume—Asuggested volume is shown for
chamber. The Soxhlet operation is not a continuous operation,
each container. However, other sizes may be required depend-
but rather a sequence of fillings and siphonings, each cycle of
ing upon the test specimen size, the amount of reagent needed
which is called a reflux change. The heat input and reagent
to complete the extraction process, and the relative sizes of
volumeareadjustedtocausetheboilingreagenttoreturntothe
related equipment.
extraction flask from the condenser at 3 to 10 reflux changes
7.1.2 Thermal Shock—Laboratory equipment that is sub-
per hour, with the extraction continuing for a minimum of 4 h
jected to non-ambient temperatures (hot or cold) shall be of
or 20 reflux changes, whichever comes first.
tempered-glass or PTFE materials.
4.1.2 Volatiles Content—Volatiles content is primarily ap-
7.1.3 Post-TestElementalAnalysis—Ifapost-testelemental
plicable to thermosetting materials, and, if required, is deter-
analysisoftheextractorresidueistobeperformed,laboratory
mined by Test Method D3530/D3530M. Volatiles content
equipment contacting the test specimen shall be constructed of
determination requires different test specimens than those used
PTFEandtestspecimencuttingshallbelimitedtotoolsthatdo
in the extraction process, since the process of determining
not leave an elemental trace.
volatiles content renders thermosetting material specimens
7.2 General Equipment:
unsuitable for subsequent organic solvent extraction.
7.2.1 Analytical Balance—The analytical balance shall be
capable of reading to within 60.1 mg.
5. Significance and Use
7.2.2 MuffleFurnace—Themufflefurnaceusedtocondition
5.1 Theprepregvolatilescontent,matrixcontent,reinforce-
glass extraction thimbles shall be capable of maintaining a
mentcontent,andfillercontentofcompositeprepregmaterials
temperature of 510 6 15°C.
are used to control material manufacture and subsequent
7.2.3 Air-Circulating Drying Oven—The drying oven shall
fabrication processes, and are key parameters in the specifica-
be capable of maintaining a temperature of 163 6 3°C.
tion and production of such materials, as well as in the
(Warning—ForsafetypurposeslistedinNFPA86,takecareto
fabrication of products made with such materials.
limit volatile concentration in the oven by controlling sample
5.2 The extraction products resulting from this test method
quantity, temperature, and ventilation.)
(the extract, the residue, or both) can be analyzed to assess
7.2.4 Desiccator—The desiccator shall be capable of con-
chemical composition and degree of purity.
taining the required test specimens.
7.3 Extraction Assembly:
6. Interferences
7.3.1 Extraction Thimbles—The extraction thimbles shall
bedeep,narrowfilteringcups,ofeitherborosilicateglassinan
6.1 Extent of Cure in Thermosetting Systems—The effi-
appropriate pore size, or fat-extracted cellulose paper, suitable
ciency of extraction for thermosetting matrix materials is
for use in the extraction chamber.
directlyrelatedtotheextentofcureoftheresinsystem.Resins
7.3.2 Hot Plate—The hot plate shall have adjustable con-
that have started to cross-link (such as B-staged resins) will be
trols suitable for heating the reagent within the reservoir flask
increasinglymoredifficulttoextractasthecureadvances.This
to 260°C and shall be capable of controlling the required
test method may not be appropriate for such materials; Test
reagent temperature within 615°C.
MethodsD3171orD2584maybebettertestmethodchoices.
7.3.3 Reservoir Flask—The reservoir flask shall be of
6.2 Reagent Selection—The proper reagent, in a suitable
borosilicateglass,ofsuitablevolume(125mLissuggested)for
quantity, must be selected for the constituents under test. The
the reagent quantity and extraction chamber volume, and shall
reagents listed in Section 8 are provided for consideration,
have a ground tapered joint capable of connection with the
particularly with regard to thermosetting materials, but cannot
remainder of the assembly.
be assured to perform well on all material systems within the
7.3.4 Soxhlet Extraction Chamber—The extraction cham-
scope of this test method.
ber shall be of borosilicate glass, with an automatic recycling
6.3 Thimble Contamination—If the extract is to undergo
siphon that recycles at a suitable liquid volume (50 mL is
further analysis, the thimble must be clean to avoid a signifi-
suggested),andwithagroundtaperedjointateachendcapable
cant source of contamination.
of connecting with the remainder of the assembly.
6.4 Reinforcement Mass Change As a Result of Reagent—
7.3.5 Condensing Chamber—The condensing chamber
The calculations of this test method assume that the reinforce-
shall be of borosilicate glass, shall be water cooled, and shall
mentmass(orfiller,iffillercontentisbeingdetermined)isnot
have a ground tapered joint capable of connecting with the
significantly affected (whether mass increase or mass loss) by
remainder of the assembly.
exposure to the reagent. Small
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