ASTM D5229/D5229M-92(2004)

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Designation: D5229/D5229M – 92 (Reapproved 2004)
Standard Test Method for
Moisture Absorption Properties and Equilibrium
Conditioning of Polymer Matrix Composite Materials
This standard is issued under the fixed designation D5229/D5229M; 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.
This standard has been approved for use by agencies of the Department of Defense.
INTRODUCTION
Consistent evaluation and comparison of the response of polymer matrix composites to moisture
absorption can only be performed when the material has been brought to a uniform through-the-
thickness moisture profile.The procedures described inTest Method D570 and Practices D618 do not
guarantee moisture equilibrium of the material. A similar, but more rigorous, procedure for
conditioning to equilibrium is described by this test method, which can also be used with fluid
moisture other than water, and which, additionally, can provide the moisture absorption properties
necessary for the analysis of single-phase Fickian moisture diffusion within such materials.
1. Scope multi-phase moisture absorption model. While the test proce-
dures themselves may be used for multi-phase materials, the
1.1 This test method covers a procedure (Procedure A) for
calculationsusedtodeterminethemoisturediffusivityconstant
the determination of moisture absorption or desorption prop-
in Procedure A are applicable only to single-phase materials.
erties in the through-the-thickness direction for single-phase
Other examples of materials and test conditions that may not
Fickian solid materials in flat or curved panel form. Also
meet the requirements are discussed in Section 1.4.
covered are procedures for conditioning test coupons prior to
1.3 The evaluation by ProcedureAof the moisture equilib-
use in other test methods; either to equilibrium in a non-
rium content material property does not assume, and is
laboratory environment (Procedure B), to equilibrium in a
therefore not limited to, single-phase Fickian diffusion behav-
standard laboratory atmosphere environment (Procedure C), or
ior.
to an essentially moisture-free state (Procedure D). While
1.4 The procedures used by this test method may be
intended primarily for laminated polymer matrix composite
performed, and the resulting data reduced, by suitable auto-
materials, these procedures are also applicable to other mate-
matic equipment.
rials that satisfy the assumptions of 1.2.
1.5 Thistestmethodisconsistentwiththerecommendations
1.2 The calculation of the through-the-thickness moisture
of MIL-HDBK-17B (1), which describes the desirable at-
diffusivity constant in Procedure A assumes a single-phase
tributes of a conditioning and moisture property determination
Fickian material with constant moisture absorption properties
procedure.
through the thickness of the specimen. The validity of the
1.6 The values stated in either SI units or inch-pound units
equations used in Procedure A for evaluating the moisture
are to be regarded separately as standard. Within the text the
diffusivity constant in a material of previously unknown
inch-pound units are shown in brackets. The values stated in
moisture absorption behavior is uncertain prior to the test, as
each system are not exact equivalents; therefore, each system
thetestresultsthemselvesdetermineifthematerialfollowsthe
must be used independently of the other. Combining values
single-phase Fickian diffusion model. A reinforced polymer
from the two systems may result in nonconformance with the
matrix composite material tested below its glass-transition
standard.
temperature typically meets this requirement, although two-
1.7 This standard does not purport to address all of the
phase matrices such as toughened epoxies may require a
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
This test method is under the jurisdiction of ASTM Committee D30 on
bility of regulatory limitations prior to use.
Composite Materials and is the direct responsibility of Subcommittee D30.04 on
Lamina and Laminate Test Methods.
Current edition approved Mar. 1, 2004. Published March 2004. Originally
approved in 1992. Last previous edition approved in 1998 as D5229/D5229M–92 Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
´1
(1998) . DOI: 10.1520/D5229_D5229M-92R04. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5229/D5229M – 92 (2004)
2. Referenced Documents 3.2.3 Fickian diffusion, n—a model of material moisture
absorption and desorption that follows Fick’s second law, as
2.1 ASTM Standards:
follows in one-dimension:
D570 Test Method for Water Absorption of Plastics
D618 Practice for Conditioning Plastics for Testing 2
]c ] c
5D
D792 Test Methods for Density and Specific Gravity (Rela-
z 2
]t
]z
tive Density) of Plastics by Displacement
D883 Terminology Relating to Plastics 3.2.4 glass transition temperature, T [Q], n—the approxi-
g
D2584 Test Method for Ignition Loss of Cured Reinforced matemidpointofthetemperaturerangeoverwhichareversible
Resins
changetakesplacebetweenaviscousorrubberyconditionand
D2734 Test Methods for Void Content of Reinforced Plas-
ahard,relativelybrittlecondition,inanamorphouspolymer,or
tics
in amorphous regions of a partially crystalline polymer.
D3171 Test Methods for Constituent Content of Composite
3.2.4.1 Discussion—The glass transition temperature of
Materials
manypolymermatrixcompositesisloweredbythepresenceof
D3878 Terminology for Composite Materials
absorbed moisture.
2.2 Military Standard:
3.2.5 moisture, n—liquid (water, jet fuel, salt water, or any
MIL-B-131 Barrier Materials, Watervaporproof,
other liquid) that is either diffused in relatively small quantity
Greaseproof, Flexible, Heat-Sealable
anddispersedthroughagasasavapor,condensedonasurface
3. Terminology as visible dew, or present in quantity sufficient for immersion
of an object.
3.1 Definitions—TerminologyD3878definestermsrelating
to high-modulus fibers and their composites. Terminology
3.2.5.1 Discussion—The dictionary definition of moisture
D883 defines terms relating to plastics. In the event of a
for this test method is extended to include not only the vapor
conflict between terms, Terminology D3878 shall have prece-
of a liquid and its condensate, but the liquid itself in large
dence over the other terminology standards.
quantities, as for immersion.
3.2 Definitions of Terms Specific to This Standard—If the
−3
3.2.6 moisture concentration, c [ML ], n—the absolute
term represents a physical quantity, its analytical dimensions
amount of absorbed moisture in a material expressed as the
are stated immediately following the term (or letter symbol) in
mass of moisture per unit volume.
fundamental dimension form, using the following ASTM
2 −1
3.2.7 moisture diffusivity constant, D [L T ], n—the prop-
standard symbology for fundamental dimensions, shown z
erty of a material that describes the rate at which the material
within square brackets: [M] for mass, [L] for length, [T] for
absorbs or desorbs moisture.
time, [Q] for thermodynamic temperature, and [nd] for non-
dimensional quantities. Use of these symbols is restricted to
3.2.7.1 Discussion—In Fickian materials this property is
analyticaldimensionswhenusedwithinsquarebrackets,asthe
relativelyindependentofthemoistureexposurelevel(andthus
symbols may have other definitions when used without the
the moisture equilibrium content material property). However,
brackets.
the moisture diffusivity constant is strongly influenced by
3.2.1 accuracy criterion, n—the maximum amount of
temperature. Moisture diffusivity can be anisotropic; the sub-
change in average moisture content for a test coupon, over the
script z indicates the value in the through-the-thickness direc-
span of the reference time period, which is allowable for the
tion for anisotropic diffusion behavior.
establishment of effective moisture equilibrium. (See also
3.2.8 moisture equilibrium, n—the condition reached by a
average moisture content, moisture equilibrium, and reference
material when there is essentially no further change in its
time period.)
average moisture content with the surrounding environment.
3.2.2 average moisture content, M (%), n—the average
Moisture equilibrium can be either absolute or effective.
amountofabsorbedmoistureinamaterial,takenastheratioof
Absolute moisture equilibrium requires no measurable change
the mass of the moisture in the material to the mass of the
in moisture content, while effective moisture equilibrium
oven-dry material and expressed as a percentage, as follows:
allowsaspecifiedsmallchangeintheaveragemoisturecontent
W 2W
i o
M,%5 3100 (1) ofamaterial(theaccuracycriterion)overaspecifiedtimespan
W
o
(the reference time period). (See also accuracy criterion,
where:
average moisture content, and reference time period.)
W = current specimen mass, g, and
i
3.2.8.1 Discussion—Effectivemoistureequilibriumisasat-
W = oven-dry specimen mass, g.
o
isfactory definition for most engineering applications. Unless
(See also oven-dry.)
otherwise specified, references to moisture equilibrium in this
test method mean effective moisture equilibrium, as quantified
3 in 10.2. Moisture equilibrium can also be either static, when
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 there is no moisture transport at all across the surfaces, or
Standards volume information, refer to the standard’s Document Summary page on
dynamic, when moisture transport exists, but the net sum for
the ASTM website.
4 the material is zero. This test method is not capable of
AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. discerning between these two types of moisture equilibrium.
D5229/D5229M – 92 (2004)
3.2.9 moisture equilibrium content, M (%), n—the maxi- 3.3.3 G(T,t)—moisture absorption or desorption function
m
mum amount of absorbed moisture that a material can contain for materials that follow Fickian diffusion.
at moisture equilibrium for a given moisture exposure level, 3.3.4 h—thickness of a material panel or plate in the
expressedasapercentofdrymaterialmass.(Seealsomoisture through-the-thickness direction for double-sided moisture ex-
saturation content.) posure.
3.2.9.1 Discussion—In polymer matrix composites, this 3.3.5 M—average moisture content of a material. The fol-
lowing subscripts denote the average moisture content for
property is relatively independent of temperature (and thus the
moisture diffusivity constant material property), but it is a specific conditions: M , the average moisture content at a
b
baseline time; M, the average moisture content at establish-
function of the moisture exposure level. For the purposes of
f
this test method M is assumed to be equivalent to the average ment of effective moisture equilibrium; M, the average mois-
m i
ture content at a given time; M , the average moisture
moisture content at effective moisture equilibrium, M.
i−1
f
content at the previous time; and M , the moisture equilibrium
3.2.10 moisture exposure level, n—ameasureordescription
m
content that is reached when a uniform through-the-thickness
of the severity of a conditioning environment in terms of the
moisture profile occurs for a given temperature and moisture
amount of liquid or vapor present. (See also moisture and
exposure level.
relative vapor level.)
3.3.5.1 Discussion—For the purposes of this test method
3.2.11 moisturesaturationcontent,n—themoistureequilib-
M and M are assumed to be equivalent.
riumcontentatthemaximumpossiblemoistureexposurelevel, m f
3.3.6 t—time.
wherein the material contains the greatest possible amount of
3.3.7 t —the maximum time required for a material to
absorbed moisture. (See also moisture equilibrium content.) m
reach moisture equilibrium under specified conditions of tem-
3.2.12 oven-dry, n—the condition of a material that has
perature and initial moisture content.
been dried in accordance with Procedure D of this test method
3.3.8 T —glass transition temperature.
until moisture equilibrium is achieved. g
3.3.9 w—the width of a nominally square moisture absorp-
3.2.13 reference time period, n—the time interval for mass
tion test coupon.
measurementusedtodefineeffectivemoistureequilibriumina
3.3.10 W—the mass of a test coupon. The following sub-
material. (See also accuracy criterion, average moisture con-
scriptsareusedtodenotethemassofatestcouponforspecific
tent, and moisture equilibrium.)
conditions: W , the mass at the baseline time; W, the mass at
b i
3.2.13.1 Discussion—A small change in the average mois-
a given time; and W , the mass at the previous time.
i−1
ture content (the accuracy criterion) for a material during the
3.3.11 z—the coordinate axis in the through-the-thickness
reference time period indicates effective moisture equilibrium.
direction for a plate or panel.
3.2.14 relative vapor level (%), n—the ratio of the pressure
of a vapor present to the pressure of the saturated vapor, at the
4. Summary of Test Method
same temperature, expressed as a percent. Applicable only to
4.1 This is a gravimetric test method that monitors the
the gaseous form of a fluid.When the vapor is water vapor the
change over time to the average moisture content of a material
term is called relative humidity. (See also moisture exposure
specimen by measuring the total mass change of a coupon that
level.)
is exposed on two sides to a specified environment. There are
3.2.15 standard laboratory atmosphere, n—an atmosphere
fourtestproceduresdescribedbythistestmethod.ProcedureA
(environment) having a temperature of 23 6 2°C
covers the determination of the two Fickian moisture diffusion
[73.4 63.6°F] and a relative humidity of 50 610%.
material properties, the moisture diffusivity constant and the
3.2.16 standardconditionedspecimen,n—thematerialcon-
moistureequilibriumcontent.Theotherthreeprocedurescover
dition of a test coupon that has reached effective moisture
material conditioning to a specific moisture environment;
equilibrium at a nominal relative humidity of 50% in accor-
Procedure B covers general moisture conditioning of material
dance with Procedure C of this test method.
coupons prior to other types of testing; Procedure C
...