ASTM D4473-95a

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 4473 – 95a An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Measuring the Cure Behavior of Thermosetting Resins
Using Dynamic Mechanical Procedures
This standard is issued under the fixed designation D 4473; 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 appropriate for use in engineering design.
1.8 The values stated in SI units are to be regarded as the
1.1 This practice covers the use of dynamic-mechanical-
standard.
oscillation instrumentation for gathering and reporting the
1.9 This standard does not purport to address all of the
thermal advancement of cure behavior of thermosetting resin.
safety concerns, if any, associated with its use. It is the
It may be used for determining the cure properties of unsup-
responsibility of the user of this standard to establish appro-
ported resins and resins supported on substrates and subjected
priate safety and health practices and determine the applica-
to various oscillatory deformations. These deformations may
bility of regulatory limitations prior to use. Specific precau-
be in shear or the dynamic compression of supported resins
tionary statements are given in Note 5.
using a dynamic mechanical instrument.
1.2 This practice is intended to provide means for determin-
NOTE 1—There is no similar or equivalent ISO standard.
ing the cure behavior of supported and unsupported thermo-
2. Referenced Documents
setting resins over a range of temperatures by free vibration
and resonant and nonresonant forced-vibration techniques, in
2.1 ASTM Standards:
accordance with Practice D 4065. Plots of modulus, cure
D 4000 Classification System for Specifying Plastic Mate-
behavior, tan delta, and damping index as a function of
rials
time/temperature are indicative of the thermal advancement or
D 4065 Practice for Determining and Reporting Dynamic
cure characteristics of a resin.
Mechanical Properties of Plastics
1.3 This practice is valid for a wide range of frequencies,
D 4092 Terminology Relating to Dynamic Mechanical
typically from 0.01 to 100 Hz. However, it is strongly
Measurements of Plastics
recommended that low-frequency test conditions, generally
E 380 Practice for Use of the International System of Units
below 1.5 Hz, will generate more definitive cure-behavior
(SI) (the Modernized Metric System)
information.
3. Terminology
1.4 This practice is intended for resin/substrate composites
that have an uncured effective elastic modulus in shear greater
3.1 Definitions—For definitions applicable to this practice
than 0.5 MPa. refer to Terminology D 4092.
1.5 Apparent discrepancies may arise in results obtained
4. Summary of Practice
under differing experimental conditions. These apparent differ-
ences from results observed in another study can usually be 4.1 A known amount of thermosetting liquid or resin-
reconciled, without changing the observed data, by reporting in impregnated substrate is placed in mechanical oscillation at
full (as described in this practice) the conditions under which fixed or natural resonant frequencies at either isothermal
the data were obtained. conditions, with a linear temperature increase or a time-
1.6 Due to possible instrumentation compliance, especially temperature relation simulating a processing condition. The
in the compressive mode, the data generated may indicate elastic or loss modulus, or both, of the composite specimen are
relative and not necessarily absolute property values. measured in shear as a function of time. The point in time when
1.7 Test data obtained by this practice is relevant and tan delta is maximum, and the elastic modulus levels after an
increase, is calculated as the gel time of the resin under the
conditions of the test.
This practice is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
NOTE 2—The particular method for measuring the elastic and loss
Current edition approved Oct. 10, 1995. Published December 1995. Originally
published as D 4473 – 85. Last previous edition D 4473 – 95.
Dynamic Mechanical Instrumentation is available from Rheometrics, Inc.,
Piscataway, NJ 08854 and The Perkin-Elmer Corp., 761 Main Ave., Norwalk, CT Annual Book of ASTM Standards, Vol 08.02.
06859-0256, (203) 762-1000. Annual Book of ASTM Standards, Vol 14.02.
D 4473
moduli and tan delta depends upon the individual instrument’s operating
following modes for measuring cure behavior in torsional shear
principles.
or dynamic compression:
7.1.1 Forced, constant amplitude, fixed frequency,
5. Significance and Use
7.1.2 Forced, constant amplitude, resonant oscillation,
5.1 This practice provides a simple means of characterizing
7.1.3 Freely decaying oscillation.
the cure behavior of thermosetting resins using very small
7.2 The apparatus shall consist of the following:
amounts of material (fewer than 3 to 5 g). The data obtained
7.2.1 Test Fixtures, a choice of the following:
may be used for quality control, research and development, and
7.2.1.1 Polished Cone and Plate (Having a Known Cone
establishment of optimum processing conditions.
Angle)—Usually a 25 or 50-mm diameter cone and plate or
5.2 Dynamic mechanical testing provides a sensitive
parallel plates are recommended for neat resins. Variations of
method for determining cure characteristics by measuring the
this tooling, such as bottom plates with concentric overflow
elastic and loss moduli as a function of temperature or time, or
rims, may be used as necessary.
both. Plots of cure behavior and tan delta of a material versus
7.2.1.2 Parallel Plates, having either smooth, polished, or
time provide graphical representation indicative of cure behav-
serrated surfaces are recommended for neat resins or prepregs
ior under a specified time-temperature profile.
having less than 6 % volatiles.
5.3 This practice can be used to assess the following:
7.2.1.3 Clamps—A clamping arrangement that permits grip-
5.3.1 Cure behavior, including rate of cure, gel, and cure
ping of the composite sample.
time.
7.2.2 Oscillatory Deformation (Strain Device)—A device
5.3.2 Processing behavior, as well as changes as a function
for applying a continuous oscillatory deformation (strain) to
of time/temperature.
the specimen. The deformation (strain) may be applied and
then released, as in free-vibration devices, or continuously
NOTE 3—The presence of the substrate prevents an absolute measure,
but allows relative measures of flow behavior during cure. applied, as in forced-vibration devices (see Table 1 of Practice
D 4065).
5.3.3 The effects of processing treatment.
7.2.3 Detectors—A device or devices for determining de-
5.3.4 Relative resin behavioral properties, including cure
pendent and independent experimental parameters, such as
behavior and damping.
force (stress or strain), frequency, and temperature. Tempera-
5.3.5 The effects of substrate types on cure.
ture should be measurable with a precision of 61°C, frequency
NOTE 4—Due to the rigidity of a supporting braid, the gel time obtained
to 61 %, and force to 61%.
from dynamic mechanical traces will be longer than actual gel time of the
7.2.4 Temperature Controller and Oven—A device for con-
unsupported resin measured at the same frequency. This difference will be
trolling the temperature, either by heating (in steps or ramps),
greater for composites having greater support-to-polymer rigidity ratios.
cooling (in steps or ramps), maintaining a constant specimen
5.3.6 Effects of formulation additives that might affect
environment, or a combination thereof. Fig. 1 illustrates typical
processability or performance.
time-temperature profiles. A temperature controller should be
5.4 For many materials, there may be a specification that
sufficiently stable to permit measurement of sample tempera-
requires the use of this practice, but with some procedural
ture to within 1°C.
modifications that take precedence when adhering to the
7.3 Nitrogen, or other inert gas supply for purging purposes.
specification. Therefore, it is advisable to refer to that material
specification before using this practice. Table 1 of Classifica-
tion System D 4000 lists the ASTM materials standards that
currently exist.
6. Interferences
6.1 Since small quantities of resin are used, it is essential
that the specimens be representative of the polymeric material
being tested.
6.2 The result is a response of the thermal advancement or
cure behavior of the resin in combination with any substrate
used to support the resin.
7. Apparatus
7.1 The function of the apparatus is to hold a neat (unmodi-
fied) resin or uncured supported composite formulation or
coated substrate of known volume and dimensions. The mate-
rial acts as the elastic and dissipative element in a mechanically
driven oscillatory shear or dynamic compression system. These
dynamic mechanical instruments operate in one or more of the
Hedvat, S., Polymer Engineering and Science, Vol 21, No. 3, February 1981. FIG. 1 Typical Temperature Profile
D 4473
8. Test Specimens require adjusting the gap setting to the manufacturer’s recom-
mended value.
8.1 The neat resin or the self-supporting composition, or
10.4 Procedure B—Supported Compositions:
both, should be representative of the polymeric material being
10.4.1 For self-supporting compositions, be certain that
tested.
there is sufficient material to fill completely the sample volume
8.2 Due to the various geometries that might be used for
on the lower plate.
dynamic mechanical curing of thermosetting resins/
10.4.2 Mount the substrate in the grips of the test instru-
composites, specimen size is not fixed by this practice. Cure
ment. A sample disk (usually 25 mm in diameter) of the
rates may be influenced by specimen thickness, so equal
self-supporting composition can be die-cut, or several plies of
volumes of material should be used for any series of compari-
prepreg can be compressed into a sheet (for example, for 3 min
sons.
at 77°C at 75 atmospheres, 1000 psi) and then a disk die
...