ASTM D3632-98
(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
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 1 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 problems, 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: D 3632 – 98
Standard Test Method for
Accelerated Aging of Adhesive Joints by the Oxygen-
Pressure Method
This standard is issued under the fixed designation D 3632; 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.
1. Scope D 907 Terminology of Adhesives
D 2339 Test Method for Strength Properties of Adhesives 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 D 907.
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
for specific time periods, then observing the physical properties
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
D 143 Methods of Testing Small Clear Specimens of Tim-
physical property at the end of 500 h.
ber
4.3.2 Constant exposure for 1000 h with a single test of the
D 454 Test Method for Rubber Deterioration by Heat and
physical property at the end of 1000 h.
Air Pressure
4.3.3 Constant exposure for up to 1000 h with a series of
D 572 Test Method for Rubber—Deterioration by Heat and
tests of the physical property after 200, 400, 600, 800, and
Oxygen
1000 h.
D 573 Test Method for Rubber—Deterioration in an Air
5. Significance and Use
Oven
5.1 This test method is useful to the adhesive manufacturer
1 in research and development or in manufacturing control. The
This test method is under the jurisdiction of ASTM Committee D-14 on
results are also used for specification acceptance or as a guide
Adhesives and is the direct responsibility of Subcommittee D14.70 on Construction
Adhesives.
in adhesive selection.
Current edition approved June 10, 1998. Published March 1999. Originally
{1
published as D 3632 – 77. Last previous edition D 3632–77(1990) .
Annual Book of ASTM Standards, Vol 04.10.
3 4
Annual Book of ASTM Standards, Vol 09.01. Annual Book of ASTM Standards, Vol 15.06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3632
5.2 The provisions for testing bonded specimens as well as 6.1.1.4 Use a thermostat to control automatically the tem-
free films are made for two purposes. First, it is possible for an perature of the heating medium.
interaction to occur between oxygen and chemicals or degra-
6.1.1.5 Record the temperature automatically throughout
dation products that may affect the degradation of the bonded
the test period. If the pressure chamber is completely im-
joints strength. Second, some increase in strength due to
mersed, use the temperature of the heating medium as the
oxidative crosslinking may not be detrimental in a bonded
temperature of the pressure chamber. Place the sensing element
assembly and in fact may be beneficial. Adhesives of this
close to the temperature-measuring device but not touching the
behavior are not satisfactorily tested by a film flexibility test.
pressure chamber. If the pressure chamber is not completely
5.3 Some users of this test method will be most interested in
immersed in the heating medium, place the sensing element in
the performance of the bonded joint; some will be most a thermometer well that extends into the pressure chamber. Fill
interested in the performance of the adhesive. In the latter case,
the thermometer well with enough water to cover the element
it is important to note that the true variance (error mean square)
so that heat will transfer easily. If a comparison has been made
of the strength of the adhesive may be obscured when the
and it has been confirmed that the temperature of the oxygen
tested control specimens or the tested aged specimens show
within the chamber is the same as the temperature of the
wood failure.
heating medium, it is permissible to take the temperature in the
5.4 Conflict of Procedure—If the procedures of this test heating medium instead of in the thermometer well. When
method conflict with those of detailed product specifications or using air as the heating medium, check the temperature in
manufacturer’s use instructions for a particular material, then various parts of the oven to determine that the oven is heating
use the latter. evenly. In any case, verify the recorded temperature by
checking with a temperature-indicating device whose sensing
6. Apparatus element is directly exposed to the oxygen within the pressure
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 D 572. 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.
Heating these materials is especially dangerous when a large
6.1.1.8 Do not expose any copper or brass parts to the
surface area is exposed. If the same equipment is used for the atmosphere nor use them in the pressure chamber or the tubing
oxygen-pressure test as for the air-pressure heat test (Test
or valves leading to it.
Method D 454), be careful and check to see that the thermo-
6.2 Testing Machine for Lap Shear Strength Tests—The
static controls are set properly because the specimens may
testing machine specifications described in 6.2.1 are the same
react with oxygen very rapidly at the temperature of the
as those described in Test Method D 2339.
air-pressure heat test. Fluids acceptable as heating media for
6.2.1 Use a testing machine capable of maintaining a
one test may be hazardous when used for the other test.
constant rate of loading of 42 to 74 N/s (600 to 1000 lbf/min)
6.1.1 Use an oxygen-pressure chamber consisting of a metal
or a constant rate of crosshead travel of 0.020 mm/s (0.050
vessel designed to retain an internal atmosphere of oxygen gas
in./min) 6 25 %. Use a testing machine with suitable grips and
under pressure, with provisions for placing specimens within it
jaws so that the specimen can be gripped tightly and held in
and for subjecting the entire chamber to controlled uniform
alignment as the load is applied. Fig. 1 shows grips and jaws
temperature. Because of the superior temperature control and
that have been found satisfactory. Place the testing machine in
heat transfer, a metal vessel completely immersed in a liquid
an atmosphere that will not noticeably alter the moisture
medium is recommended for referee tests. Ensure that the
content of the specimens developed under the conditions
apparatus conforms to the following requirements:
prescribed in 10.2.
6.1.1.1 The chamber can be any size; however, it must be
6.3 Air Curing and Drying Oven—Except for some modi-
large enough so that the specimens can be hung within it
fication, the oven specifications described (in 6.3.1 through
vertically, without crowding them, letting them touch each
6.3.9) are the same as those described in Test Method D 573.
other, or letting them touch the sides of the chamber.
6.3.1 Use an oven whose interior size is (minimum) 0.40 m
6.1.1.2 The source of heat is optional, but a location outside
3 3 3
(1 ft ) to (maximum) 1.33 m (36 ft ) or any equivalent
of the aging chamber itself is required.
volume.
6.1.1.3 The heating medium is optional. Water, air, or other
6.3.2 Suspend the specimens vertically without letting them
fluids that will not ignite when oxygen is present may be used.
touch each other or the sides of the oven.
Water has an advantage because it transfers heat rapidly and is
6.3.3 The temperature variation in various parts of the oven
noncombustible. When using air for the heating medium,
shall not be allowed to exceed 2°C (4°F).
thoroughly circulate the heated air by mechanically agitating it,
6.3.4 For the heating medium, use air circulated within the
and use baffles as needed to prevent local overheating and dead
chamber at atmospheric pressure.
spots. Do not use oils or other combustible fluids as heating
media for this test because they are extremely hazardous when 6.3.5 Any source of air may be used, if it is located in the air
oxygen is present. supply outside of the chamber itself.
D 3632
8. Sampling
8.1 Sampling Method—When several test specimen panels
are made or films cast and groups of individual specimens are
aged for different time intervals, mix all the specimens in a box
and draw at random from the box for assignment to a given
group.
8.2 Sample Size—Use at least five test specimens to deter-
mine the original physical properties of each sample. Also use
five or more specimens of the same material for each exposure
period of the test. But for purposes of statistical analyses
described in a later section, the number of specimens in the
control group and in each aged group should be the same. The
user may increase the number of specimens in each group in
response to the size of the property change to be detected, the
degree of confidence desired, and the test result variability.
This subject is further considered in Annex A1.
9. Test Specimens
9.1 Lap-shear test specimens must be made from the same
adherends and adhesive materials that are actually used in
service. A tension lap-shear specimen made like the ones in
FIG. 1 Grips and Jaws
Fig. 2 and Fig. 3 is recommended. Methods for preparing
wood-to-wood specimens are similar to those described in
Method D 2339 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 Method D 143.
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
smaller distances between the saw kerfs such as 12.7 mm (0.5
7.1 Adhesive, the adhesive to be tested.
in.), as in Fig. 4.
7.2 Wood for wood-to-wood and wood-to-metal specimens,
rotary cut, sliced or sawn and jointed veneers 3.2 to 6.4 mm ( ⁄8
to ⁄4 in.) thick, shall be free of defects such as knots, cracks,
short grain, or any discolorations or soft spots indicative of
decay. The species to be used will be decided by the adhesive
manufacturer or by the party requesting these tests. Generally
a high-density wood such as Douglas-fir, hemlock, southern
pine, or yellow birch is desirable.
7.3 Metal for wood-to-metal specimen dimesions be 1.6 to
1 1
3.2 mm ( ⁄16to ⁄8 in.) thick. The metal will be selected by the
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
Metric Equivalents
should be the same as the material expected to be bonded in Dimen- Toler- Dimen- Toler-
sion ance sion ance
service with finish or surface treatment to be selected by the
mm in.
adhesive manufacturer or by the party requesting the test,
A 82.6 60.25 3.25 60.010
except that lubricants or other combustible materials shall be B 25.4 60.25 1.00 60.010
C 3.17 60.10 0.125 60.004
removed from the surface by solvent cleaning before exposure
in the oxygen-pressure vessel. FIG. 2 Wood-to-Wood Tension Shear Test Specimen
D 3632
(140°F) for 12 h. These recommendations are not intended to
override any
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