ASTM D1673-94(2004)
(Test Method)Standard Test Methods for Relative Permittivity And Dissipation Factor of Expanded Cellular Polymers Used For Electrical Insulation (Withdrawn 2006)
Standard Test Methods for Relative Permittivity And Dissipation Factor of Expanded Cellular Polymers Used For Electrical Insulation (Withdrawn 2006)
SCOPE
1.1 These test methods cover procedures for determining the relative permittivities and dissipation factor of flat sheets or slabs of expanded cellular polymers of both the rigid and flexible types, at frequencies from 60 Hz to 100 MHz. Provision is made for measurements on specimens up to 50 mm (2 in.) in thickness, but it is recommended that specimens greater than 25 mm (1 in.) in thickness shall be tested at frequencies up to a maximum of only about 1 MHz.
1.2 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 .
WITHDRAWN RATIONALE
These test methods cover procedures for determining the relative permittivities and dissipation factor of flat sheets or slabs of expanded cellular polymers of both the rigid and flexible types, at frequencies from 60 Hz to 100 MHz. Provision is made for measurements on specimens up to 50 mm (2 in.) in thickness, but it is recommended that specimens greater than 25 mm (1 in.) in thickness shall be tested at frequencies up to a maximum of only about 1 MHz.
Formerly under the jurisdiction of Committee D09 on Electrical and Electronic Insulating Materials, these test methods were withdrawn in January 2006. The Executive Committee felt strongly that Committee D09 could not support the practice of maintaining a standard for which the expertise may not lie within the current committee membership, or for which the utilization of the standard is questionable.
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An American National Standard
Designation:D1673–94 (Reapproved 2004)
Standard Test Methods for
Relative Permittivity And Dissipation Factor of Expanded
Cellular Polymers Used For Electrical Insulation
This standard is issued under the fixed designation D1673; 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.
INTRODUCTION
Althoughfundamentallysimilartotestmethodsusedforsolidelectricalinsulatingmaterialsinsheet
or plate form, certain modifications in the procedures and measurement techniques are necessary for
the proper determination of the relative permittivities and dissipation factors of foamed or expanded
cellularpolymers.Thisisoccasionedbythefactthatinmany,ifnotmost,instancesexpandedcellular
materialshavesurfacesthatprecludetheuseofconventionalelectrodessuchasmetalfoilattachedby
petrolatum and similar adhesives, or conducting silver paint applied by brushing or spraying.
Furthermore, it is generally true that slabs or plates of expanded cellular materials are available only
in substantially greater thicknesses than those commonly used for test specimens of solid insulation.
1. Scope D 1056 Specification for Flexible Cellular Materials
Sponge or Expanded Rubber
1.1 These test methods cover procedures for determining
D1711 Terminology Relating to Electrical Insulation
therelativepermittivitiesanddissipationfactorofflatsheetsor
slabs of expanded cellular polymers of both the rigid and
3. Terminology
flexible types, at frequencies from 60 Hz to 100 MHz.
3.1 For definitions of relative permittivity, dissipation fac-
Provision is made for measurements on specimens up to 50
tor, and loss index, refer to Test Methods D150 or Terminol-
mm (2 in.) in thickness, but it is recommended that specimens
ogy D1711.
greater than 25 mm (1 in.) in thickness shall be tested at
frequencies up to a maximum of only about 1 MHz.
4. Significance and Use
1.2 This standard does not purport to address all of the
4.1 Relative Permittivity:
safety concerns, if any, associated with its use. It is the
4.1.1 Because a relatively large proportion of their volumes
responsibility of the user of this standard to establish appro-
arecomposedofmoreorlessuniformlydistributed,isolated,or
priate safety and health practices and determine the applica-
interconnected gas-filled cells, foamed or expanded cellular
bility of regulatory limitations prior to use.
polymers always have lower relative permittivities, at a given
2. Referenced Documents frequency and temperature, than the solid base resins from
2 which they are prepared.
2.1 ASTM Standards:
4.1.2 The relative permittivities of expanded cellular poly-
D150 Test Methods for AC Loss Characteristics and Per-
mers are important because they determine the increase in
mittivity (Dielectric Constant) of Solid Electrical Insula-
capacitance between conductors, or between conductors and
tion
ground, that will result when a circuit or component is
D374 Test Methods for Thickness of Solid Electrical Insu-
encapsulated in such a material, over their corresponding
lation
values before encapsulation (when air is the surrounding
medium). Likewise, the relative permittivities of an expanded
cellular polymer may serve as a measure of the decrease of
These test methods are under the jurisdiction of ASTM Committee D09 on
such capacitances caused by substitution of the expanded
Electrical and Electronic Insulating Materials and are the direct responsibility of
materialforasolidencapsulatingcompoundorresinofknown
Subcommittee D09.12 on Electrical Tests.
relative permittivity.
Current edition approved March 1, 2004. Published March 2004. Originally
approved in 1959. Last previous edition approved in 1998 as D1673–79(1998).
4.1.3 In transmission lines, such as coaxial cable, television
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
lead-in cables, and so forth, the reduction of relative permit-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
tivity of an expanded material from its value in the original
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. solid state has significant usefulness in design, since the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1673–94 (2004)
capacitance per foot of cable, and such cable characteristics as made for the performance of relative permittivity and dissipa-
velocity of propagation and characteristic impedance are all tion factor tests at any desired frequency in the range between
dependent upon the relative permittivity of the insulating 60 Hz and 100 MHz.
material.
6. Electrodes
4.1.4 In wave guides, radomes, dielectric lenses, and so
forth, for use at radio frequencies, if the cellular polymer is
6.1 Expanded cellular polymers, in general, do not have
nonmagnetic, the relative permittivity (usually in combination
surfaces suitable for attachment of conventional metal foil or
with the dissipation factor) determines such transmission
conducting paint electrodes, so that prefabricated rigid metal
characteristics as velocity of propagation, attenuation distance,
plate electrodes must usually be employed for relative permit-
decibel loss per meter, phase factor, complex index of refrac-
tivity and dissipation factor tests. Such electrode systems may
tion, index of absorption, and dielectric conductivity.
be of either the direct contact type or the noncontacting type.
4.1.5 Therelativepermittivitydeterminationmayserveasa
6.2 Direct-Contact Electrode Systems—Direct-contacttype
productioncontroltestforbatch-to-batchuniformityofagiven
electrodes may be one of the following:
expanded cellular polymer. For expanded cellular nonpolar
6.2.1 A calibrated micrometer electrode system of the
polymers(polyethylene,polystyrene,andsoforth),therelative
Hartshorn-Wardtype,showninFig.1(Fig.10ofTestMethods
permittivity measurement may constitute a useful control test
D150), is particularly useful for samples 50 mm (2 in.) in
on the density of the product.
diameteranduptoabout6.35mm(0.25in.)thick.Thissystem
may be used at any frequency up to 100 MHz. Specimens are
NOTE 1—For useful information concerning the relationship of the
lightly clamped and in contact with both electrodes. Care must
relative permittivity of an expanded cellular material to its density and to
the relative permittivity of the solid constituent, see Appendix X1.
be observed to avoid compressing or crushing the material.
6.2.2 Two rigid plate electrodes with a single sheet speci-
4.2 Dissipation Factor and Loss Index:
men between and in contact with them may be used with the
4.2.1 The loss index of an expanded cellular polymer is a
specimen the same size as the electrodes (see Table 1). It may
measure of the ac power loss in the material. When two
bedesirabletoenclosethissysteminametalboxforshielding.
materials have the same relative permittivities, their relative
A wide range of specimen sizes and thicknesses may be
dielectric losses per unit volume at a given frequency and
handled by various modifications of this system. However, the
applied voltage gradient are directly indicated by their respec-
upper frequency limit is relatively low for larger thick speci-
tive dissipation factors.
mens.
4.2.2 Since the dielectric loss in an insulating material
6.2.3 Athree-plateelectrodesystemwithadoublespecimen
results in the generation of heat, with a subsequent rise in
arrangedinasandwichformmaybeusedandisrecommended
temperature of the material, it is desirable in most cases that
for large sheets of thick materials for tests at relatively low
these losses be as low as possible. This is important not only
frequencies. The two specimens should be of nearly the same
from the standpoint of the overall efficiency of an electrical
thickness. The two outer plates are connected together and to
system but also because the increased temperature generally
groundortothelowsideofthemeasuringapparatus.Thethird
causes significant changes in both the relative permittivity and
(middle) electrode serves as the high side. The system has the
loss and thereby may contribute to instability of operation,
advantage of being practically self-shielding.
particularly in radio-frequency circuits.
6.3 NoncontactingElectrodeSystems(“AirGap”Methods):
4.2.3 The dielectric loss, as measured by the dissipation
6.3.1 A calibrated micrometer electrode system of the
factor and loss index, may serve as a quality control criterion
Hartshorn-Ward type, shown in Fig. 1 may be used, with the
and as a means of determining batch-to-batch uniformity of a
specimen the same size as or smaller than the 50-mm (2-in.)
product. It is also an excellent means of measuring the effects
diameter of the electrodes. Disk specimens are most suitable,
of weathering, aging, and absorption of moisture by the
butsquaresmaybeusedifthelengthofthediagonalisslightly
expandedcellularpolymer,theseinfluencesgenerallyresulting
less than the diameter of the electrodes. Specimens 25 to 50
in substantial increases in the dielectric loss index.
4.2.4 The dissipation factor (usually in combination with
therelativepermittivity)isusefulinestimatingthecontribution
of the dielectric loss to the total attenuation in coaxial cables,
and in calculations of the transmission characteristics of
radomes, dielectric lenses, and related devices, as indicated in
4.1.4.
5. Apparatus
5.1 Electrical Measurement Apparatus, consisting of suit-
able bridge and resonant-circuit equipment having character-
istics as prescribed in Test Methods D150. Provision shall be
For details see von Hippel,A. R., Dielectrics and Waves, Part I, John Wiley &
Sons, Inc., New York, NY 1954, Ch. 9, pp. 26–37. FIG. 1 Micrometer Electrode System
D1673–94 (2004)
TABLE 1 Suggested Specimen and Electrode Sizes and Maximum Test Frequencies for Relative Permittivity and Dissipation Factor
Measurements on Expanded Cellular Plastic Sheets of Various Thicknesses up to 50 mm (2 in.).
Thickness of Specimen Approximate Diameter of Round, or Length of Side of Square Specimens and Electrodes Test Frequency, max, Approximate MHz
Recommended Permissible
mm in. Recommended Permissible
mm in. mm in.
A
Up to 6.35 0.25 101.6 4.0 50.8 2.0 10.
...
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