ASTM D3632-98(2004)
(Test Method)Standard Test Method for Accelerated Aging of Adhesive Joints by the Oxygen-Pressure Method
Standard Test Method for Accelerated Aging of Adhesive Joints by the Oxygen-Pressure Method
SIGNIFICANCE AND USE
This test method is useful to the adhesive manufacturer in research and development or in manufacturing control. The results are also used for specification acceptance or as a guide in adhesive selection.
The provisions for testing bonded specimens as well as free films are made for two purposes. First, it is possible for an interaction to occur between oxygen and chemicals or degradation products that may affect the degradation of the bonded joints strength. Second, some increase in strength due to oxidative crosslinking may not be detrimental in a bonded assembly and in fact may be beneficial. Adhesives of this behavior are not satisfactorily tested by a film flexibility test.
Some users of this test method will be most interested in the performance of the bonded joint; some will be most interested in the performance of the adhesive. In the latter case, it is important to note that the true variance (error mean square) of the strength of the adhesive may be obscured when the tested control specimens or the tested aged specimens show wood failure.
Conflict of Procedure—If the procedures of this test method conflict with those of detailed product specifications or manufacturer’use instructions for a particular material, then use the latter.
SCOPE
1.1 This test method describes how to estimate the relative resistance to deterioration of adhesive films and adhesive-bonded joints placed in a high-pressure oxygen environment. The instructions include both wood-to-wood and wood-to-metal joints as well as free film of adhesive. The effects of chemicals such as fire retardants, preservatives, or wood extractives, can be evaluated by using materials containing these chemicals for adherends.
1.2 This test method is primarily intended for elastomer-based construction adhesives, but is also applicable to other types of adhesives that may be susceptible to oxygen degradation. This accelerated test does not correlate exactly with the natural aging of the adhesive because of the varied conditions of natural aging and the absence of factors such as moisture and stress. The results of this accelerated test are only comparative and must be evaluated against the performance of bonded joints whose natural and accelerated aging characteristics are known.
1.3 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.
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Designation:D3632–98(Reapproved2004)
Standard Test Method for
Accelerated Aging of Adhesive Joints by the Oxygen-
Pressure Method
This standard is issued under the fixed designation D3632; 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.
1. Scope D907 Terminology of Adhesives
D2339 Test Method for Strength Properties ofAdhesives in
1.1 This test method describes how to estimate the relative
Two-Ply Wood Construction in Shear by Tension Loading
resistance to deterioration of adhesive films and adhesive-
bonded joints placed in a high-pressure oxygen environment.
3. Terminology
The instructions include both wood-to-wood and wood-to-
3.1 Definitions—Many definitions in this test method are
metal joints as well as free film of adhesive. The effects of
defined in Terminology D907.
chemicals such as fire retardants, preservatives, or wood
extractives, can be evaluated by using materials containing
4. Summary of Test Method
these chemicals for adherends.
4.1 This test method entails subjecting specimens with
1.2 This test method is primarily intended for elastomer-
known physical properties to a controlled aging environment
based construction adhesives, but is also applicable to other
forspecifictimeperiods,thenobservingthephysicalproperties
types of adhesives that may be susceptible to oxygen degrada-
again and noting any changes. The controlled environment
tion. This accelerated test does not correlate exactly with the
consists of elevated temperature (70°C) (158°F) and oxygen at
natural aging of the adhesive because of the varied conditions
elevated pressure 2.07 MPa (300 psi).
of natural aging and the absence of factors such as moisture
4.2 Three types of test specimens are offered. The party
and stress. The results of this accelerated test are only
requesting the adhesive evaluation will choose the type of
comparative and must be evaluated against the performance of
specimen to be used.
bonded joints whose natural and accelerated aging character-
Physical Property
istics are known.
Specimen Type Configuration
Tested
1.3 This standard does not purport to address all of the
A wood-to-wood lap shear strength
safety concerns, if any, associated with its use. It is the B wood-to-metal lap shear strength
C unsupported film flexibility
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4.3 Three different oxygen-pressure aging exposures are
bility of regulatory limitations prior to use.
offered. Use any exposure with any of the above specimens.
The party requesting the adhesive evaluation will choose the
2. Referenced Documents
exposure to which the specimens are subjected.
2.1 ASTM Standards:
4.3.1 Constant exposure for 500 h with a single test of the
D143 Test Methods for Small Clear Specimens of Timber
physical property at the end of 500 h.
D454 Test Method for Rubber Deterioration by Heat and
4.3.2 Constant exposure for 1000 h with a single test of the
Air Pressure
physical property at the end of 1000 h.
D572 Test Method for Rubber—Deterioration by Heat and
4.3.3 Constant exposure for up to 1000 h with a series of
Oxygen
tests of the physical property after 200, 400, 600, 800, and
D573 Test Method for Rubber—Deterioration in an Air
1000 h.
Oven
5. Significance and Use
5.1 This test method is useful to the adhesive manufacturer
This test method is under the jurisdiction of ASTM Committee D14 on
Adhesives and is the direct responsibility of Subcommittee D14.70 on Construction
in research and development or in manufacturing control. The
Adhesives.
results are also used for specification acceptance or as a guide
Current edition approved April 1, 2004. Published April 2004. Originally
in adhesive selection.
approved in 1977. Last previous edition approved in 1998 as D3632 – 98. DOI:
10.1520/D3632-98R04. 5.2 The provisions for testing bonded specimens as well as
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
free films are made for two purposes. First, it is possible for an
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
interaction to occur between oxygen and chemicals or degra-
Standards volume information, refer to the standard’s Document Summary page on
dation products that may affect the degradation of the bonded
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3632–98 (2004)
joints strength. Second, some increase in strength due to temperatureofthepressurechamber.Placethesensingelement
oxidative crosslinking may not be detrimental in a bonded close to the temperature-measuring device but not touching the
assembly and in fact may be beneficial. Adhesives of this pressure chamber. If the pressure chamber is not completely
behavior are not satisfactorily tested by a film flexibility test. immersed in the heating medium, place the sensing element in
5.3 Some users of this test method will be most interested in a thermometer well that extends into the pressure chamber. Fill
the performance of the bonded joint; some will be most the thermometer well with enough water to cover the element
interested in the performance of the adhesive. In the latter case, so that heat will transfer easily. If a comparison has been made
itisimportanttonotethatthetruevariance(errormeansquare) and it has been confirmed that the temperature of the oxygen
of the strength of the adhesive may be obscured when the within the chamber is the same as the temperature of the
tested control specimens or the tested aged specimens show heating medium, it is permissible to take the temperature in the
wood failure. heating medium instead of in the thermometer well. When
5.4 Conflict of Procedure—If the procedures of this test using air as the heating medium, check the temperature in
method conflict with those of detailed product specifications or various parts of the oven to determine that the oven is heating
manufacturer’s use instructions for a particular material, then evenly. In any case, verify the recorded temperature by
use the latter. checking with a temperature-indicating device whose sensing
element is directly exposed to the oxygen within the pressure
6. Apparatus
chamber.
6.1 Oxygen-Pressure Vessel—The specifications for the
6.1.1.6 Maintain positive, rapid, and complete circulation of
oxygen-pressure vessel described in 6.1.1.1 through 6.1.1.8 are
the heating medium so as to ensure accurate, uniform heating.
the same as those described in Test Method D572. Adequate
6.1.1.7 The pressure chamber should have a reliable safety
safety provisions are important when heating oxidizable or-
valve or rupture diaphragm set for release at 3.448 MPa (500
ganic materials in oxygen, since the rate of reaction may
psi) pressure.
become very rapid and very high pressures may develop.
6.1.1.8 Do not expose any copper or brass parts to the
Heating these materials is especially dangerous when a large
atmosphere nor use them in the pressure chamber or the tubing
surface area is exposed. If the same equipment is used for the
or valves leading to it.
oxygen-pressure test as for the air-pressure heat test (Test
6.2 Testing Machine for Lap Shear Strength Tests—The
Method D454), be careful and check to see that the thermo-
testing machine specifications described in 6.2.1 are the same
static controls are set properly because the specimens may
as those described in Test Method D2339.
react with oxygen very rapidly at the temperature of the
6.2.1 Use a testing machine capable of maintaining a
air-pressure heat test. Fluids acceptable as heating media for
constant rate of loading of 42 to 74 N/s (600 to 1000 lbf/min)
one test may be hazardous when used for the other test.
or a constant rate of crosshead travel of 0.020 mm/s (0.050
6.1.1 Useonoxygen-pressurechamberconsistingofametal
in./min) 6 25 %. Use a testing machine with suitable grips and
vessel designed to retain an internal atmosphere of oxygen gas
jaws so that the specimen can be gripped tightly and held in
under pressure, with provisions for placing specimens within it
alignment as the load is applied. Fig. 1 shows grips and jaws
and for subjecting the entire chamber to controlled uniform
that have been found satisfactory. Place the testing machine in
temperature. Because of the superior temperature control and
heat transfer, a metal vessel completely immersed in a liquid
medium is recommended for referee tests. Ensure that the
apparatus conforms to the following requirements:
6.1.1.1 The chamber can be any size; however, it must be
large enough so that the specimens can be hung within it
vertically, without crowding them, letting them touch each
other, or letting them touch the sides of the chamber.
6.1.1.2 The source of heat is optional, but a location outside
of the aging chamber itself is required.
6.1.1.3 The heating medium is optional. Water, air, or other
fluids that will not ignite when oxygen is present may be used.
Water has an advantage because it transfers heat rapidly and is
noncombustible. When using air for the heating medium,
thoroughlycirculatetheheatedairbymechanicallyagitatingit,
and use baffles as needed to prevent local overheating and dead
spots. Do not use oils or other combustible fluids as heating
media for this test because they are extremely hazardous when
oxygen is present.
6.1.1.4 Use a thermostat to control automatically the tem-
perature of the heating medium.
6.1.1.5 Record the temperature automatically throughout
the test period. If the pressure chamber is completely im-
mersed, use the temperature of the heating medium as the FIG. 1 Grips and Jaws
D3632–98 (2004)
an atmosphere that will not noticeably alter the moisture 8.2 Sample Size—Use at least five test specimens to deter-
content of the specimens developed under the conditions mine the original physical properties of each sample. Also use
prescribed in 10.2. five or more specimens of the same material for each exposure
6.3 Air Curing and Drying Oven—Except for some modi- period of the test. But for purposes of statistical analyses
fication, the oven specifications described (in 6.3.1 through described in a later section, the number of specimens in the
6.3.9) are the same as those described in Test Method D573. control group and in each aged group should be the same. The
6.3.1 Use an oven whose interior size is (minimum) 0.40 m user may increase the number of specimens in each group in
3 3 3
(1 ft ) to (maximum) 1.33 m (36 ft ) or any equivalent response to the size of the property change to be detected, the
volume. degree of confidence desired, and the test result variability.
6.3.2 Suspend the specimens vertically without letting them This subject is further considered in Annex A1.
touch each other or the sides of the oven.
9. Test Specimens
6.3.3 The temperature variation in various parts of the oven
9.1 Lap-shear test specimens must be made from the same
shall not be allowed to exceed 2°C (4°F).
adherends and adhesive materials that are actually used in
6.3.4 For the heating medium, use air circulated within the
service. A tension lap-shear specimen made like the ones in
chamber at atmospheric pressure.
Fig. 2 and Fig. 3 is recommended. Methods for preparing
6.3.5 Anysourceofairmaybeused,ifitislocatedintheair
wood-to-wood specimens are similar to those described in Test
supply outside of the chamber itself.
Method D2339 with modifications to accommodate mastic
6.3.6 Install a thermometer in the upper central portion of
consistency adhesives.
the chamber, near the center of the specimens, to measure the
9.2 Wood-to-Wood Test Panel Preparation:
actual temperature.
9.2.1 Cut the veneer into suitable sizes and assemble it in
6.3.7 Use a thermostat to control the temperature automati-
pairs with the grain direction of the two sheets parallel to each
cally.
other. Fig. 4 shows a size that has been found convenient, and
6.3.8 Circulate the heated air throughout the oven by
in this case the grain is parallel to the shorter dimension. Make
mechanically agitating it. When using a motor-driven fan, the
sure the veneer is within 6 1 % of the moisture content
air must not come in contact with the fan motor brush
recommended by the manufacturer of the adhesive. When the
discharge because there is danger of ozone forming.
manufacturer does not give a recommendation, use a moisture
6.3.9 Use baffles where they are needed to prevent local
content of 10 to 12 % based on ovendry weight in accordance
overheating and dead spots.
with Sections 122 to 125 of Test Methods D143.
9.2.2 If the specimens fail predominantly at the saw kerfs,
7. Materials
prepare and test a new set of specimens with thicker veneers or
7.1 Adhesive, the adhesive to be tested.
smaller distances between the saw kerfs such as 12.7 mm (0.5
7.2 Wood for wood-to-wood and wood-to-metal specimens,
in.), as in Fig. 4.
rotary cut, sliced or sawn and jointed veneers 3.2 to 6.4 mm ( ⁄8
9.2.3 Follow the directions of the adhesive manufacturer
to ⁄4 in.) thick, shall be free of defects such as knots, cracks,
when applying the adhesive, but use a notched trowel to spread
short grain, or any discolorations or soft spots indicative of
adhesives of mastic consistency. Use a trowel with notches
decay. The species to be used will be decided by the adhesive
shaped like equilateral triangles 3.2 mm ( ⁄8 in.) on a side, and
manufacturer or by the party requesting these tests. Generally
spaced 3.2 mm ( ⁄8 in.) apart. During troweling, hold the trowel
a high-density wood such as Douglas-fir, hemlock, southern
at approximately a 45-deg angle.Apply enough adhesive to fill
pine, or yellow birch is desirable.
7.3 Metal for wood-to-metal specimen dimensions be 1.6
1 1
to3.2mm( ⁄16to ⁄8in.)thick.Themetalwillbeselectedbythe
adhesive manufacturer or by the party requesting the test,
except that the metal used shall not be reactive as, for example,
magnesium plate.
7.3.1 The mill finish or chemical treatment of the surface
should be the same as the material expected to be bonded in
service with finish or surface treatment to be selected by the
adhesive manufacturer or by the party requesting the test,
except that lubricants or other combustible materials shall be
removed from the surface by solvent cleaning before exposure
in the oxygen-pressure vessel.
Metric Equivalents
8. Sampling
Dimen- Toler- Dimen- Toler-
sion ance sion ance
8.1 Sampling Method—When several test specimen panels
...
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