ASTM D1879-99
(Practice)Standard Practice for Exposure of Adhesive Specimens to High-Energy Radiation
Standard Practice for Exposure of Adhesive Specimens to High-Energy Radiation
SCOPE
1.1 The purpose of this practice is to define conditions for the exposure of polymeric adhesives in bonded specimens to high-energy radiation prior to determination of radiation-induced changes in physical or chemical properties. This recommended practice specifically covers the following kinds of radiation: gamma or X-ray radiation, electron or beta radiation, neutrons, and mixtures of these such as reactor radiation.
1.2 This practice specifies only the conditions of irradiation but does not cover the preparation of test specimens, testing conditions, or the evaluation of test. These are covered in the various ASTM methods or specifications for specific materials.
1.3 This practice covers procedures for the following five types of exposure: Procedure A -Exposure at ambient conditions. Procedure B -Exposure at controlled temperature. Procedure C -Exposure in a medium other than air. Procedure D- Exposure under load. Procedure E- Exposure combining two or more of the variables listed in Procedures A to D. Note 1-The problems of measuring the properties of materials during irradiation involve shielding and remote control facilities and are, therefore, not considered in this practice.
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Designation:D1879 –99
Standard Practice for
Exposure of Adhesive Specimens to High-Energy Radiation
This standard is issued under the fixed designation D1879; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope cannot and will not substitute for a practical knowledge of the
instrument used for a particular procedure.
1.1 The purpose of this practice is to define conditions for
1.5.2 RadioFrequency: Warning—Personswithpacemak-
the exposure of polymeric adhesives in bonded specimens to
ers may be affected by the radio frequency.
high-energy radiation prior to determination of radiation-
induced changes in physical or chemical properties. This
2. Referenced Documents
recommended practice specifically covers the following kinds
2.1 ASTM Standards:
of radiation: gamma or X-ray radiation, electron or beta
D618 Practice for Conditioning Plastics and Electrical
radiation, neutrons, and mixtures of these such as reactor
Insulating Materials for Testing
radiation.
D907 Terminology of Adhesives
1.2 This practice specifies only the conditions of irradiation
D1671 Test Method forAbsorbed Gamma Radiation Dose
but does not cover the preparation of test specimens, testing
in the Fricke Dosimeter
conditions, or the evaluation of test. These are covered in the
D1672 Practice for Exposure of Polymeric Materials to
variousASTMmethodsorspecificationsforspecificmaterials.
High-Energy Radiation
1.3 This practice covers procedures for the following five
D2953 Classification System for Polymeric Materials for
types of exposure:
Service in Ionizing Radiation
Procedure A—Exposure at ambient conditions.
2.2 ANSI Document:
Procedure B—Exposure at controlled temperature.
N1.1 Glossary of Terms in Nuclear Science and Technol-
Procedure C—Exposure in a medium other than air.
ogy
Procedure D—Exposure under load.
2.3 IEEE Documents:
Procedure E—Exposure combining two or more of the
278 Classifying Electrical Insulating Materials Exposed to
variables listed in Procedures A to D.
Neutron and Gamma Radiation
NOTE 1—Theproblemsofmeasuringthepropertiesofmaterialsduring
323 Qualifying Class 1E Equipment for Nuclear Power
irradiation involve shielding and remote control facilities and are, there-
Generating Stations
fore, not considered in this practice.
3. Terminology
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are provided for
3.1 Many terms in this practice are defined in Terminology
information purposes only.
D907.
1.5 This standard does not purport to address all of the
3.2 gray, n—the unit of absorbed dose when the energy per
safety concerns, if any, associated with its use. It is the
unit mass imparted to matter by radiation is one joule per
responsibility of the user of this standard to establish appro-
kilogram.
priate safety and health practices and determine the applica-
3.3 rad, n—the unit of absorbed dose when the energy per
bility of regulatory limitations prior to use.
unitmassimpartedtomatterbyradiationis100ergspergram.
1.5.1 Electrical Hazard: Warning—Theusersofthisprac-
–2
NOTE 2—To convert from rad to gray (Gy), multiply by 1.00 3 10 .
tice must be aware that there are inherent dangers associated
with the use of electrical instrumentation and that this practice
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 15.06.
Discontinued; see 1984 Annual Book of ASTM Standards, Vol 12.02.
1 5
This practice is under the jurisdiction ofASTM Committee D-14 onAdhesives Discontinued; see 1985 Annual Book of ASTM Standards, Vol 12.02.
and is the direct responsibility of Subcommittee D14.80 on Metal Bonding Available from American National Standards Institute, 11 W. 42nd St., 13th
Adhesives. Floor, New York, NY 10036.
Current edition approved Oct. 10, 1999. Published December 1999. Originally Available from Institute of Electrical and Electronics Engineers, 345 E. 47th
published as D1879–61. Last previous edition D1879–70 (1994). St., New York, NY 10017.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1879
4. Significance and Use which the specimen has been exposed be reported as well as
the irradiation dose in energy absorbed units.
4.1 The procedures outlined in this practice are designed to
5.6 Awide variation in the stability of the various chemical
standardizetheexposureofadhesive-bondedspecimensforthe
structures on exposure to radiation makes it difficult to select
purpose of studying the effects of high-energy radiation, but
specific exposure levels for testing. Polystyrene requires the
have been made flexible enough so that a large variety of
absorption of about 50 times as much radiation energy for the
conditions may be met within the scope of this one irradiation
formation of one crosslink as does polyethylene. At the other
method. Because of this flexibility in the procedures it is
end of the scale, poly(methylmethacrylate) and polytetrafluo-
important that the experimenter have some idea of the kind of
roethyleneshowchangesinengineeringpropertiesatabout ⁄20
changes that will occur, and of the conditions that will affect
theexposurerequiredforchangesinpolyethylene.Anaromatic
these changes.
ringattachedtothemainchainatfrequentregularintervalshas
been found to confer marked stability toward radiation, while
5. Effects of Irradiation
a quaternary carbon atom in the polymer chain leads to
5.1 Exposuretoradiationresultsinextensivechangesinthe
cleavage under radiation and a loss of strength at fairly low
nature of high polymers, which owe their unique properties to
exposures. The exposure levels should therefore be those
chemicallinkinginto giant molecules of chain or netstructure.
which will produce significant changes in a stipulated property
These chain or net structures may be cross-linked by radiation
rather than a specified fixed irradiation dose. Furthermore, the
into a rigid, three-dimensional network or in other cases, may
change in property may progress at different rates, with some
be cleaved into smaller molecules to produce a weaker
materials changing rapidly once a change has been initiated,
material. Both may occur at the same time. In all cases some
while others may change quite slowly. It is necessary therefore
low molecular weight fragments are produced and, if expo-
to irradiate to several fixed levels of property change in order
sures are large enough, general decomposition results.
to establish the rate of change (see 13.2).
5.2 The first result of the reaction of high-energy radiation
5.7 Materials that have been exposed to reactor radiation
with polymers is the formation of free radicals or excited
willbecomeradioactive.Forpurehydrocarbons,theamountof
molecular fragments. The rate at which these molecular frag-
induced radioactivity is not large, but metallic and other
ments are formed may be much greater than their annihilation
inorganicadherendsandfillersandsmallamountsofimpurities
rate, and this leads to the accumulation of reactive species
may become highly radioactive and thus create a handling
within the irradiated material and to the possibility of continu-
problem. The other common radiation sources to which poly-
ing reactions for days or weeks after the specimen has been
meric materials will be exposed will not normally produce
removed from the radiation field. Because of these post-
significant amounts of induced radioactivity. The obvious
irradiation reactions it has been necessary to standardize the
solution would be to expose adhesive-bonded metallic speci-
times and conditions of storage between irradiation and testing
mens in non-neutron environments only. Unfortunately it is
of specimens.
very difficult to calculate for a given reactor spectrum the
5.3 The resultant changes in the molecular structure of
equivalent dosage in a gamma source. For exact work, where
polymeric materials by exposure to radiation are dependent on
the reactor spectrum is being studied, exposure in a reactor
therespectiveratesofrecombination,crosslinking,orcleavage
would give the only accurate results.
of the molecular fragments. These rates are affected by the
5.8 Metallic adherends such as cadmium will produce large
mobility of the molecular fragments (which is strongly influ-
sources of secondary radiation, which will significantly add to
enced by temperature) and by the concentration of the reac-
the absorbed dose of the adhesive.
tants.
5.4 The concentration of reactive species will vary with the
6. Test Specimens
rate of absorption of radiation. Either radiation intensity or
6.1 Wherever possible, use the type of specimens in accor-
dose rate is therefore specified in reporting the results of tests,
dance with the ASTM test methods for the specific properties
even though a dose rate effect is not often observed.The effect
to be measured.
of dose rate and specimen thickness is observed when irradia-
6.2 Where it is not possible to utilize standard test speci-
tions are carried out in the presence of oxygen, where oxygen
mens,makeirradiatedandnonirradiatedspecimensofthesame
reacts with radicals produced in the irradiated material. This
size and shape.
oxygen reaction will be diffusion controlled. The reactivity of
6.3 Sinceorganicadherendswouldbesensitivetoradiation,
irradiated specimens toward oxygen makes it necessary to
they should be tested independently of the adhesive assembly
specify whether irradiations are carried out in air. The acces-
under the same conditions, using irradiated and nonirradiated
sibilitytoanairsupplyundepletedinoxygenshouldbeassured
adherend specimens.
if possible.
5.5 The localized concentration of reactive species during
7. Conditioning
irradiation will vary, depending on the type of radiation
employed. The proton and carbon recoils from neutron bom- 7.1 Condition specimens to be exposed in air in accordance
with Procedure A of Practice D618.
bardment produce densely ionized tracks in the specimen
compared to the diffuse ionization in the wake of protons or 7.2 Condition specimens to be exposed in a gas other than
electrons. The effect of different types of radiation may air at the temperature of exposure in an appropriate container
−3
thereforebedifferent.Itisrequiredthatthetypeofradiationto at a pressure of 10 Pa (10 mm Hg) or less for at least 8 h
D1879
followed by three flushes with the gas to be present during 9.3 Condition the specimens as outlined in 8.4.
exposure. After flushing, fill the container with the exposure 9.4 After conditioning in accordance with 7.1,
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