ASTM D4502-92(2019)
(Test Method)Standard Test Method for Heat and Moisture Resistance of Wood-Adhesive Joints
Standard Test Method for Heat and Moisture Resistance of Wood-Adhesive Joints
SIGNIFICANCE AND USE
5.1 This test method can serve as a useful tool for durability assessment and service life forecasting.
5.1.1 This test method can be used to measure the effects of heat and moisture and the effect of their interaction on adhesives and bonded joints. Knowledge of these effects is useful to an adhesive formulator or manufacturer. Moist heat aging is particularly useful for determining the effects of acidic adhesive systems on the hydrolysis of wood adherends.
5.1.2 This test method provides a means of comparing the rate of degradation of an unknown adhesive-adherend combination to the rate of degradation of a known combination in thermal or hydrolytic aging environments. Such a comparison can be useful to adhesive manufacturers for introducing a new product to the market and for helping designers selecting adhesives.
5.1.3 This test method does not duplicate any natural service environment, but it does provide a means of estimating the service life of joints in similar environments. Service-life estimates are useful to designers of bonded structures or structures using bonded products.
5.2 Service-life estimates rely on the assumption that the chemical degradation mechanism is the same at the elevated aging temperatures as at the service temperature. However, this may not be true in every case. This possibility, together with the variability in specimen preparation, in the aging exposures, and in the strength measurements, require that caution be used in accepting the estimate of service life.
SCOPE
1.1 The purpose of this test method is to estimate the resistance of adhesive-bonded joints to thermal and hydrolytic degradation.
1.2 This test method is primarily for wood-to-wood joints but may be applied to joints of wood to other materials.
1.3 The effects of chemicals such as fire retardants, preservatives, and extractives in the wood upon joint degradation resistance can be estimated.
1.4 This test method does not account for the effects of stress, the other principal degrading factor, nor does it account for cyclic or variable temperature or moisture levels.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4502 − 92 (Reapproved 2019)
Standard Test Method for
Heat and Moisture Resistance of Wood-Adhesive Joints
This standard is issued under the fixed designation D4502; 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.
1. Scope D907Terminology of Adhesives
D2304Test Method for Thermal Endurance of Rigid Elec-
1.1 The purpose of this test method is to estimate the
trical Insulating Materials
resistance of adhesive-bonded joints to thermal and hydrolytic
D2307 Test Method for Thermal Endurance of Film-
degradation.
Insulated Round Magnet Wire
1.2 This test method is primarily for wood-to-wood joints
D2339Test Method for Strength Properties ofAdhesives in
but may be applied to joints of wood to other materials.
Two-PlyWood Construction in Shear byTension Loading
1.3 The effects of chemicals such as fire retardants, 2.2 IEEE Standard:
preservatives, and extractives in the wood upon joint degrada-
IEEENo.1GeneralPrinciplesforTemperatureLimitsinthe
tion resistance can be estimated. Rating of Electrical Equipment
1.4 This test method does not account for the effects of
3. Terminology
stress, the other principal degrading factor, nor does it account
3.1 Definitions
for cyclic or variable temperature or moisture levels.
3.1.1 For definitions of terms used in this test method, refer
1.5 The values stated in SI units are to be regarded as
to Terminology D907.
standard. The values given in parentheses after SI units are
3.2 shear strength, n—in an adhesive joint, the maximum
providedforinformationonlyandarenotconsideredstandard.
average stress when a force is applied parallel to the joint.
1.6 This standard does not purport to address all of the
3.2.1 Discussion—In most adhesive test methods, the shear
safety concerns, if any, associated with its use. It is the
strength is actually the maximum average stress at failure of
responsibility of the user of this standard to establish appro-
the specimen, not necessarily the true maximum stress in the
priate safety, health, and environmental practices and deter-
material.
mine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accor-
4. Summary of Test Method
dance with internationally recognized principles on standard-
4.1 The degradation of adhesive joints is a physicochemical
ization established in the Decision on Principles for the
process. The speed of degradation is related to the levels of
Development of International Standards, Guides and Recom-
temperature, moisture (and other chemicals), and physical
mendations issued by the World Trade Organization Technical
stress to which the joint is exposed. This test method is based
Barriers to Trade (TBT) Committee.
on the principles of chemical kinetics and uses theArrehenius
temperature dependence relationship to estimate the long-term
2. Referenced Documents
effects of heat and moisture at the service temperature.
2.1 ASTM Standards:
4.2 Specimens whose unaged properties have been esti-
D897Test Method forTensile Properties ofAdhesive Bonds
mated by control tests are subjected to an accelerated thermal
D905Test Method for Strength Properties of Adhesive
or hydrolytic aging environment in groups. Aging is acceler-
Bonds in Shear by Compression Loading
ated by using elevated temperature. Periodically, a group of
specimens is removed from the aging environment and tested.
The estimated property after aging and the time of aging are
This test method is under the jurisdiction of ASTM Committee D14 on
recorded.Afterseveralgroupshavebeentestedinthismanner,
Adhesives and is the direct responsibility of Subcommittee D14.70 on Construction
Adhesives.
the rate of property loss in the aging environment can be
Current edition approved March 1, 2019. Published March 2019. Originally
estimated. This basic experiment is repeated at several other
approved in 1985. Last previous edition approved in 2011 as D4502–92(2011).
elevated temperatures, and the rates of property loss at those
DOI: 10.1520/D4502-92R19.
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 Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
the ASTM website. 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4502 − 92 (2019)
temperatures estimated. The rate of property loss relationship perature over saturated salt solutions. Wide-neck canning jars
to temperature is estimated. This relationship can be extrapo- with volumes of 3 ⁄2 L (1 gal), rubber gaskets, and clamp lids
lated to lower service temperatures for estimating service life. haveprovensatisfactoryattemperaturesof100°C(212°F)and
below. The jars must have a platform inside (without legs) to
4.3 This test method employs a smaller version of the Test
support specimens above the saturated salt solution. A 6mm
MethodD905blockshearspecimen,butothershearstrengthor
( ⁄4in.) diameter bead of silicone sealant around the inside
tensile strength specimens may also be used.
surface of the jar and about 5 cm (2 in.) above the bottom
providesaledgetosupporttheplatform.Theplatformmustbe
5. Significance and Use
perforated to permit free-flow of water vapor. It may be cut
5.1 Thistestmethodcanserveasausefultoolfordurability
from any material that is resistant to corrosion, heat, and
assessment and service life forecasting.
moisture. Perforated high-density hardboard has proven satis-
5.1.1 This test method can be used to measure the effects of
factory. The platform must be cut in half to pass through the
heat and moisture and the effect of their interaction on
neck of the jar.An aging jar with platform is shown in Fig. 1.
adhesives and bonded joints. Knowledge of these effects is
The jars must be placed in an aging oven, such as described in
useful to an adhesive formulator or manufacturer. Moist heat
5.1, to achieve the required temperature.
agingisparticularlyusefulfordeterminingtheeffectsofacidic
6.4 Water Baths—Constant-level water baths capable of
adhesive systems on the hydrolysis of wood adherends.
controltowithin0.5°Cofthedesiredtemperaturearerequired.
5.1.2 This test method provides a means of comparing the
The baths must be able to contain 100 specimens.
rate of degradation of an unknown adhesive-adherend combi-
nation to the rate of degradation of a known combination in
6.5 Testing Machine—The testing machine shall have a
thermal or hydrolytic aging environments. Such a comparison
capacity of not less than 3000 kg (6210 lbf) in compression.
can be useful to adhesive manufacturers for introducing a new
The machine shall be capable of maintaining a uniform rate of
product to the market and for helping designers selecting
loading such that the load may be applied with a continuous
adhesives.
motion of the movable head to the maximum load at a rate of
5.1.3 This test method does not duplicate any natural
10.0 6 5 mm/min (0.40 in./min) with a permissible variation
serviceenvironment,butitdoesprovideameansofestimating
of+0.5%.
the service life of joints in similar environments. Service-life
6.6 Shearing Tool—A shearing tool similar to the tool
estimates are useful to designers of bonded structures or
pictured in Test Method D905 is satisfactory. The tool must
structures using bonded products.
have a self-aligning seat to ensure uniform lateral distribution
5.2 Service-life estimates rely on the assumption that the
of the load.
chemical degradation mechanism is the same at the elevated
agingtemperaturesasattheservicetemperature.However,this
7. Materials
may not be true in every case. This possibility, together with
7.1 Adhesive to Be Tested:
thevariabilityinspecimenpreparation,intheagingexposures,
7.2 Joints—Wood for wood-to-wood joints or joints of
and in the strength measurements, require that caution be used
wood to metal or plastic shall be free of defects such as knots,
in accepting the estimate of service life.
cracks, short-grain and sharp-grain deviations, or any discol-
6. Apparatus
orations or soft spots indicative of decay. Generally, a high-
density uniform-textured wood is desirable so that the maxi-
6.1 Aging Ovens—Ovens are required that are capable of
mum stress will be placed on the adhesive joint during testing.
control within 62 % of specified exposure temperature
The standard shall be hard maple (Acer saccharum or Acer
throughout the chamber for extended periods of time (60.5°C
nigrum) having a minimum specific gravity of 0.65 (based on
control is desirable). The ovens must be capable of operating
oven-dry weight and volume). Other species may be used
at temperatures from 60 to 175°C. The oven must have an
whereevaluationoftheadhesive’sperformanceincontactwith
internal capacity for up to 100 specimens well-spaced and
that species is a specific requirement.
supported on racks to allow free air flow.
7.3 Saturated Salt Solutions—A constant relative humidity
6.2 Environmental Chambers—Chambers for moist-heat
at a given temperature can be maintained in sealed aging jars
aging must be capable of 60.5°C temperature and 0.5%
byasaturatedaqueoussolutionincontactwithanexcessofthe
relative humidity control uniformly throughout the chamber.
solid phase of a specific salt. Tables are available that show
The chamber must be capable of operating at temperatures
relative humidities at given temperatures for many salts.
from 60 to 90°C and relative humidity from 60 to 80%. The
Sodium chloride is recommended. A saturated solution of
chamber must have the capacity for up to 100 specimens
sodiumchloridewillproducearelativehumidityof73to76%
well-spaced and supported on racks to allow free air flow.
overthetemperaturerangefrom40to100°C.Thistranslatesto
6.3 Moist Aging Jars—Heat-resistant glass jars are required
wood moisture content in the approximate range from 9 to
to expose specimens to constant relative humidity and tem-
13%.
Millett,M.A.,Western,L.J.,andBooth,J.J.,“AcceleratedAgingofCellulosic
Materials: Design andApplication of a Heating Chamber,” TAPPI, Vol 50, No. 11, Dean, J.A., ed., Lange’s Handbook of Chemistry, 12th ed., McGraw-Hill Book
1967, pp. 74A–80A. Co., Inc., 1978.
D4502 − 92 (2019)
FIG. 1 Moist Aging Jar with a Shelf for Aging Specimens Over a Saturated Salt Solution
8. Test Specimens 8.3.1 Cut rough 25.4mm (1in.) lumber into 127 or 63 by
305mm (5 or 2 ⁄2 by 12in.) billets as required by Section 9.
8.1 A modified block shear specimen (Fig. 2) is suggested.
Saw each billet in half through the thickness using a bandsaw.
ThespecimenissimilartothespecimenofTestMethodD905,
Joint the surface of each half that is to be bonded and plane to
but its smaller size allows more specimens to fit in the aging
8mm( ⁄16in.)thickness.(Note1)Bondthebilletsasdescribed
chambers. Other specimens such as used inTest Method D897
in Test Method D905.
orTestMethodD2339arealsosatisfactory.IfatypefromTest
MethodD2339isselected,thenuse6.5mm( ⁄4in.)lumberfor
NOTE 1—If during strength testing specimens fail in compression
each lamina, and increase the specimen length to 130 mm (5.1
paralleltothegrainattheends,thelaminaethicknessshouldbeincreased
5 3
from8mm( ⁄16 in.) to 9.5 mm ( ⁄8 in.) or greater, as necessary.
in.) while maintaining the 25.4mm (1in.) overlap. Other
bonded joints or products may also be tested if a suitable
8.3.2 After bonding, trim one edge and one end of each
specimen can be devised.
panel. Then cut two rows of five specimens each from the 63
by 305mm (2 ⁄2 by 12in.) panels, as shown in Fig. 3, or four
8.2 Condition the wood at 23 6 2°C (73.4+3.6°F) and
rows of five specimens each from the 127 by 305mm (5 by
relative humidity of either 30 or 65%, or other conditions,
12in.) panels.
depending on the adhesive manufacturer’s requirement.
8.3 Prepare modified shear block specimens as described in
NOTE 2—The adhesive should be thoroughly cured by hot pressing,
Test Method D905 with the following exceptions: oven heating, high-frequency heating, or whatever method is appropriate.
D4502 − 92 (2019)
9.2.1 Inagivenexperiment(servicelife,ratecomparison,or
quality control) pair the 6.5 by 127 (or 63) by 305-mm billets
randomly for bonding into panels.
9.2.2 Distributethespecimensfromeachpanelaccordingto
the plan shown in the appropriate table for the experiment.
Service-life estimation Table 1
Rate comparison Table 2
Quality control Table 3
9.2.3 The distribution of specimens for subsequent data
analysis is summarized by the block experimental designs
shown in Table 4 for each of the experiments.
10. Procedure
10.1 Initial Strength:
10.1.1 Condition the control specimens to equilibrium
moisture content (EMC) at 23+2°C and 50 6 2% relative
humidity or other conditions as agreed upon by the parties
involved. One to four weeks may be required to reach EMC,
depending on the beginning moisture content.
10.1.2 Test the specimens (after they reach EMC) in the
shear tool with the universal test machine crosshead moving at
10+0.05 mm/min (0.400 6 0.002 in./min). Store the speci-
mens in a plastic bag, or remove them one at a time from the
conditioned environment during testing. Record the strength
and estimated percentage of wood failure for each specimen.
10.2 Service Life Estimate:
10.2.1 Aging temperatures are given inTable 4. For a given
FIG. 2 Modified Block Shear Specimen
temperature/moisture condition, mount five groups (10 speci-
mens per group) on suitable racks for dry aging, place in jars
Undercured adhesives cause unwanted results in the early stages of
for moist aging, or string each group on stainless steel wire for
elevated temperature aging.
wet aging.
8.4 Mark each specimen using a template before cutting to
10.2.2 Estimate five aging intervals that will produce ap-
indicate the panel and position in the panel.
proximately equal strength decrements to a total strength loss
of25to30%fromtheinitialstrengthforeachofthefiveaging
9. Sampling
temperatures. Previous aging experience may not be available,
9.1 Sample Size:
especially for new adhesives. If this is the case, use the
9.
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.