ASTM D570-98(2005)
(Test Method)Standard Test Method for Water Absorption of Plastics
Standard Test Method for Water Absorption of Plastics
SCOPE
1.1 This test method covers the determination of the relative rate of absorption of water by plastics when immersed. This test method is intended to apply to the testing of all types of plastics, including cast, hot-molded, and cold-molded resinous products, and both homogeneous and laminated plastics in rod and tube form and in sheets 0.13 mm [0.005 in.] or greater in thickness.
1.2 The values given in SI units are to be regarded as standard. The values stated in brackets are for information only.
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. Note 1
ISO 62 is technically equivalent to this test method.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D570–98 (Reapproved 2005)
Standard Test Method for
Water Absorption of Plastics
This standard is issued under the fixed designation D570; 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 properties, dimensions, or appearance have been determined,
as a guide to the effects of exposure to water or humid
1.1 Thistestmethodcoversthedeterminationoftherelative
conditions on such properties; and second, as a control test on
rate of absorption of water by plastics when immersed. This
the uniformity of a product. This second function is particu-
test method is intended to apply to the testing of all types of
larly applicable to sheet, rod, and tube arms when the test is
plastics, including cast, hot-molded, and cold-molded resinous
made on the finished product.
products, and both homogeneous and laminated plastics in rod
3.2 Comparison of water absorption values of various plas-
and tube form and in sheets 0.13 mm [0.005 in.] or greater in
tics can be made on the basis of values obtained in accordance
thickness.
with 7.1 and 7.4.
1.2 The values given in SI units are to be regarded as
3.3 Ideal diffusion of liquids into polymers is a function of
standard. The values stated in brackets are for information
the square root of immersion time. Time to saturation is
only.
strongly dependent on specimen thickness. For example,Table
1.3 This standard does not purport to address all of the
1 shows the time to approximate time saturation for various
safety concerns, if any, associated with its use. It is the
thickness of nylon-6.
responsibility of the user of this standard to establish appro-
3.4 The moisture content of a plastic is very intimately
priate safety and health practices and determine the applica-
related to such properties as electrical insulation resistance,
bility of regulatory limitations prior to use.
dielectric losses, mechanical strength, appearance, and dimen-
NOTE 1—ISO62 is technically equivalent to this test method.
sions. The effect upon these properties of change in moisture
content due to water absorption depends largely on the type of
2. Referenced Documents
exposure (by immersion in water or by exposure to high
2.1 ASTM Standards:
humidity), shape of the part, and inherent properties of the
D647 Practice for Design of Molds for Test Specimens of
plastic. With nonhomogeneous materials, such as laminated
Plastic Molding Materials
forms, the rate of water absorption may be widely different
2.2 ISO Standard:
through each edge and surface. Even for otherwise homoge-
ISO62 Plastics—Determination of Water Absorption
neous materials, it may be slightly greater through cut edges
than through molded surfaces. Consequently, attempts to
3. Significance and Use
correlatewaterabsorptionwiththesurfaceareamustgenerally
3.1 This test method for rate of water absorption has two
be limited to closely related materials and to similarly shaped
chief functions: first, as a guide to the proportion of water
specimens: For materials of widely varying density, relation
absorbed by a material and consequently, in those cases where
between water-absorption values on a volume as well as a
therelationshipsbetweenmoistureandelectricalormechanical
weight basis may need to be considered.
4. Apparatus
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
and is the direct responsibility of Subcommittee D20.50 on Durability of Plastics.
4.1 Balance—An analytical balance capable of reading
Current edition approved Nov. 1, 2005. Published January 2006. Originally
0.0001 g.
approved in 1940. Last previous edition approved in 1998 as D570-98. DOI:
10.1520/D0570-98R05.
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 Additional information regarding diffusion of liquids in polymers can be found
the ASTM website. in the following references: (1) Diffusion, Mass Transfer in Fluid Systems, E.L.
Withdrawn. The last approved version of this historical standard is referenced Cussler, Cambridge University Press, 1985, ISBN 0-521-29846-6, (2) Diffusion in
on www.astm.org. Polymers, J. Crank and G.S. Park, Academic Press, 1968, and (3) “Permeation,
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., Diffusion, and Sorption of Gases and Vapors,” R.M. Felder and G.S. Huvard, in
4th Floor, New York, NY 10036. Methods of Experimental Physics, Vol 16C, 1980, Academic Press.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D570–98 (2005)
TABLE 1 Time to Saturation for Various Thickness of Nylon-6
Type of Dimensions to Be Measured to the
Specimen Nearest 0.025 mm [0.001 in.]
Thickness, mm Typical Time to 95 % Saturation, h
Molded disk thickness
1 100
Sheet thickness
2 400
Rod length and diameter
3.2 1 000
Tube inside and outside diameter, and wall thickness
10 10 000
25 62 000
6. Conditioning
6.1 Three specimens shall be conditioned as follows:
6.1.1 Specimens of materials whose water-absorption value
4.2 Oven, capable of maintaining uniform temperatures of
would be appreciably affected by temperatures in the neigh-
50 63°C [122 65.4°F] and of 105 to 110°C [221 to 230°F].
borhood of 110°C [230°F], shall be dried in an oven for 24 h
at 50 63°C [122 65.4°F], cooled in a desiccator, and imme-
5. Test Specimen
diately weighed to the nearest 0.001 g.
5.1 The test specimen for molded plastics shall be in the
form of a disk 50.8 mm [2 in.] in diameter and 3.2 mm [ ⁄8 in.] NOTE 4—If a static charge interferes with the weighing, lightly rub the
surface of the specimens with a grounded conductor.
in thickness (see Note 2). Permissible variations in thickness
are 60.18 mm [60.007 in.] for hot-molded and 60.30 mm
6.1.2 Specimens of materials, such as phenolic laminated
[60.012 in.] for cold-molded or cast materials.
plastics and other products whose water-absorption value has
been shown not to be appreciably affected by temperatures up
NOTE 2—The disk mold prescribed in the Molds for Disk Test
to 110°C [230°F], shall be dried in an oven for1hat105to
Specimens Section of Practice D647 is suitable for molding disk test
specimens of thermosetting materials but not thermoplastic materials. 110°C [221 to 230°F].
6.1.3 When data for comparison with absorption values for
5.2 ISO Standard Specimen—The test specimen for homo-
other plastics are desired, the specimens shall be dried in an
geneous plastics shall be 60 by 60 by 1 mm. Tolerance for the
oven for 24 h at 50 63°C [122 65.4°F], cooled in a desic-
60-mm dimension is 62mmand 60.05 mm for the 1-mm
cator, and immediately weighed to the nearest 0.001 g.
thickness.This test method and ISO62 are technically equiva-
lent when the test specimen described in 5.2 is used.
7. Procedure
5.3 Thetestspecimenforsheetsshallbeintheformofabar
7.1 Twenty-Four Hour Immersion—The conditioned speci-
76.2 mm [3 in.] long by 25.4 mm [1 in.] wide by the thickness
mens shall be placed in a container of distilled water main-
of the material. When comparison of absorption values with
tained at a temperature of 23 61°C [73.4 61.8°F], and shall
molded plastics is desired, specimens 3.2-mm [ ⁄8-in.] thick
rest on edge and be entirely immersed.At the end of 24, + ⁄2 ,
should be used. Permissible variations in thickness shall be
−0 h, the specimens shall be removed from the water one at a
0.20 mm [60.008 in.] except for materials which have greater
time, all surface water wiped off with a dry cloth, and weighed
standard commercial tolerances.
tothenearest0.001gimmediately.Ifthespecimenis ⁄16in.or
5.4 Thetestspecimenforrodsshallbe25.4-mm[1-in.]long
less in thickness, it shall be put in a weighing bottle immedi-
for rods 25.4 mm in diameter or under and 12.7-mm [ ⁄2-in.]
ately after wiping and weighed in the bottle.
long for larger-diameter rods. The diameter of the specimen
7.2 Two-Hour Immersion—For all thicknesses of materials
shall be the diameter of the finished rod.
having a relatively high rate of absorption, and for thin
5.5 The test specimen for tubes less than 76 mm [3 in.] in
spec
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