ASTM D3012-00
(Test Method)Standard Test Method for Thermal-Oxidative Stability of Propylene Plastics Using a Specimen Rotator Within an Oven
Standard Test Method for Thermal-Oxidative Stability of Propylene Plastics Using a Specimen Rotator Within an Oven
SCOPE
1.1 This test method provides a means for estimating the resistance of polypropylene, in molded form, to accelerated aging by heat in the presence of air using a forced draft oven.
1.2 The stability determined by this test method is not directly related to the suitability of the material for use when different environmental conditions prevail and shall not be used to predict performance.
Note 1--The specified thermal levels in this test method are considered sufficiently severe to cause failure of commercial grades of heat-stable polypropylene within a reasonable period of time. If desired, lower temperatures can be applied to estimate the performance of polypropylene with lower heat stabilities.
1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.4 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.
Note 2--This test method and ISO 4577-1983 are technically similar but different in preparation of test specimens, thickness of test specimen, measurement of the number of air flow changes in the ovens, and the number of air changes per hour required.
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Designation: D 3012 – 00
Standard Test Method for
Thermal-Oxidative Stability of Polypropylene Using a
Specimen Rotator Within an Oven
This standard is issued under the fixed designation D 3012; 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 * Ovens for Evaluation of Electrical Insulation
D 5423 Specification for Forced-Convection Laboratory
1.1 This test method provides a means for estimating the
Ovens for Evaluation of Electrical Insulation
resistance of polypropylene, in molded form, to accelerated
E 1 Specification for ASTM Thermometers
aging by heat in the presence of air using a forced draft oven.
E 77 Test Method for Inspection and Verification of Ther-
1.2 The stability determined by this test method is not
mometers
directly related to the suitability of the material for use when
E 220 Test Method for Calibration of Thermocouples by
different environmental conditions prevail and shall not be
Comparison Techniques
used to predict performance.
E 608 Specification for Metal-Sheathed Base-Metal Ther-
NOTE 1—The specified thermal levels in this test method are considered 5
mocouples
sufficiently severe to cause failure of commercial grades of heat-stable
E 644 Test Methods for Testing Industrial Resistance Ther-
polypropylene within a reasonable period of time. If desired, lower
mometers
temperatures can be applied to estimate the performance of polypropylene
E 691 Practice for Conducting an Interlaboratory Study to
with lower heat stabilities.
Determine the Precision of a Test Method
1.3 The values stated in SI units are to be regarded as the
E 1137 Specification for Industrial Platinum Resistance
standard. The values in parentheses are for information only.
Thermometers
1.4 This standard does not purport to address all of the
2.2 ISO Standard:
safety concerns, if any, associated with its use. It is the
ISO 4577–1983 Plastics—Polypropylene and Propylene
responsibility of the user of this standard to establish appro-
Copolymers—Determination of Thermal Oxidative Sta-
priate safety and health practices and determine the applica-
bility in Air-Oven Method
bility of regulatory limitations prior to use.
ISO 1873 Plastics—Polypropylene and Propylene-
NOTE 2—This test method and ISO 4577–1983 are technically similar
Copolymer Thermoplastics:
but different in preparation of test specimens, thickness of test specimen,
Part 1: Designation
measurement of the number of air flow changes in the ovens, and the
Part 2: Determination of Properties
number of air changes per hour required.
3. Terminology
2. Referenced Documents
3.1 Definitions—The definitions of plastics used in this test
2.1 ASTM Standards:
method are in accordance with Terminology D 883 unless
D 618 Practice for Conditioning Plastics and Electrical
otherwise indicated.
Insulating Materials for Testing
D 883 Terminology Relating to Plastics
4. Summary of Test Method
D 3641 Practice for Injection Molding Test Specimens of
4.1 Aging is accelerated by exposing the specimens to an
Thermoplastic Molding and Extrusion Materials
elevated temperature in a forced draft oven equipped with a
D 4101 Specification for Polypropylene Injection and Ex-
biaxial or uniaxial rotating specimen holder.
trusion Materials
4.2 Visual examination is used to determine the time to
D 5374 Test Methods for Forced-Convection Laboratory
failure. The time to failure of the material is taken as the
number of days after which the specimen shows localized
crazing, crumbling, or discoloration, or a combination thereof.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-
als. Annual Book of ASTM Standards, Vol 10.02.
Current edition approved Nov. 10, 2000. Published January 2001. Originally Annual Book of ASTM Standards, Vol 14.03.
published as D 3012 – 72. Last previous edition D 3012 – 99. Annual Book of ASTM Standards, Vol 14.02.
2 7
Annual Book of ASTM Standards, Vol 08.01. Available from American National Standards Institute, 11 W. 42nd St., 13th
Annual Book of ASTM Standards, Vol 08.02. Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3012
5. Significance and Use 6.2.4 Resistance thermometers shall comply with the re-
quirements of Test Methods E 644 and Specification E 1137,
5.1 Under the severe conditions of this test method, the
and be calibrated in accordance with NIST Special Publication
specimens undergo degradation at a rate that is dependent upon
9,10
250-22.
the thermal endurance of the polypropylene material under
6.3 Molding Press, designed to operate at 200 6 5°C (3926
examination.
9°F).
5.2 The thermal level of this test method is considered
6.4 Injection Molding Unit, meeting the requirements of
sufficiently severe to cause failure of commercial grades of
Practice D 3641.
heat-stable polypropylene within a reasonable period of time.
6.5 Mold:
If desired, lower temperatures can be applied to estimate the
6.5.1 Compression Mold, comprised of the following:
performance of polypropylene materials with lower heat sta-
6.5.1.1 Compression Molding Chase, having a blanked-out
bility.
area of suitable size (Note 3) and capable of producing a plaque
5.3 The technique of specimen rotation described in this test
1.00 6 0.05 mm (0.039 6 0.002 in.) thick.
method provides an estimate of the life-temperature relation-
ship of polypropylene. If this test method is conducted at
NOTE 3—A 152.4 by 152.4-mm (6 by 6-in.) blanked-out section has
different temperatures on the same material, a more reliable
been found satisfactory.
estimate of the life-temperature relationship of polypropylene
6.5.1.2 Backing Plates, large enough to cover this chase and
is determined. This test method can be conducted at several
strong enough to resist warping or distortion, under the
temperatures and the data interpreted through use of the
molding conditions. Polished steel plates, 3 mm (0.1 in.) thick,
Arrhenius relation, by plotting the logarithms of times to
are satisfactory.
failure against the reciprocals of the temperatures in kelvins
6.5.2 Injection Mold, designed using the guidelines speci-
(K). Temperatures in the range from 100 to 150°C, with
fied in Practice D 3641. The mold shall be capable of produc-
intervals of 10°C, are suggested for this purpose.
ing either a plaque having a thickness of 1.00 6 0.05 mm
5.4 The stability as determined under the prescribed test
(0.039 6 0.002 in.) from which 50 by 10 by 1.00-mm(2by
method is not directly related to the suitability of the compound
0.4 by 0.039-in.) specimens may be die cut, or mold a standard
for a use where different conditions prevail.
test specimen, 50 by 10 by 1.00 mm.
5.5 The specimen rotation technique of thermal aging in-
6.6 Parting Sheets—Fluoropolymer, polyester, or other film
creases the probability that all specimens will be exposed
that will not affect the long-term thermal stability of polypro-
similarly and that the effect of temperature gradients in an oven
pylene, 0.05 to 0.20 mm (0.002 to 0.008 in.) thick. The film
will be minimized.
must be free of wrinkles and foreign matter, such as lubricants
and oils.
6. Apparatus
6.7 Cutting Die, to produce 50 by 10-mm (2 by 0.4-in.)
6.1 Oven, mechanical convection type for controlled circu-
specimens from either a compression-molded or injection-
lation of air, with adjustable air intake and exhaust facilities,
molded plaque. The die must be sharp and free of nicks.
and designed for air velocities around 6 250 1000 mm/s (197
8 6.8 Specimen Holder—The specimen holder may be biaxi-
6 49 ft/min). The oven shall meet the requirements of
ally rotated or uniaxially rotated provided that the test speci-
Specification D 5423.
mens are in a stream of air having a relative velocity about
6.1.1 The oven shall be equipped with a temperature-control
1000 mm/s (197 ft/min). Illustrations of suitable apparatus for
system designed to maintain the test temperature range from
biaxially and uniaxially rotated specimen holders are shown in
150 6 1°C (302 6 1.8°F) and a device to prevent temperature
Figs. 1 and 2, respectively. Biaxial rotation increases the
override. With the oven adjusted to the nominal test tempera-
probability that all specimens will be exposed similarly. In the
ture of 150°C, the override shall be set at 154°C (309°F). A
case of dispute, the use of biaxial rotation shall be the reference
bimetallic-strip temperature switch has been found satisfactory.
method.
6.2 Oven Temperature Measurement System, consisting of a
6.8.1 Biaxially Rotated Specimen Holder (see Fig. 1) .
thermocouple, thermometer, or resistance thermometer as the
The frequency of rotation about the horizontal and vertical axes
sensor, together with its associated conditions and readout
–1
shall be 1 to 3 min .
instrumentation covering at least the temperature range from 0
6.8.2 Uniaxially Rotated Specimen Holder (see Fig. 2).
to 200°C (32 to 372°F).
The drum peripheral velocity shall be such that the air stream
6.2.1 The thermometer must cover the range in one-degree
impinges on the flat section of the test specimens at about 1
subdivisions. It must be tested for bulb stability and standard-
m/s.
ized, in accordance with Test Method E 77.
6.9 Air Velocity Meter, nondirectional resistance wire type
6.2.2 The secondary standard shall be ASTM Thermometer
for measuring the air velocity in the oven.
67C of Specification E 1.
6.2.3 Thermocouples shall comply with the requirements of
Specification E 608 and shall be calibrated in accordance with
Method E 220.
Mangum, B. W., “Platinum Resistance Thermometer Calibration,” NBS Special
Publication 250-22 (1987).
Available from National Institute of Standards Technology, Gaithersburg, MD.
8 11
A Precision Scientific Freas Model 835 B, or Blue M POM-206C-1, or Standard Scientific Supply Company, Model CS191, or equivalent, can be
equivalent, can be used. used.
D 3012
made to position the anemometer’s electronics in a way as to
minimize the degree of exposure to the heated air exiting the
oven.
6.11 Metal Clips, lined with fluorocarbon film or other
materials that have no adverse effect on the oxidative thermal
stability of polypropylene.
7. Specimen Preparation
7.1 The test specimens shall be cut from either a compres-
sion–molded plaque or injection-molded plaque prepared from
granules or other homogeneous molding material. Plaques
shall be prepared as follows:
7.2 Compression Molding:
7.2.1 Adjust the temperature of the platens to 200 6 5°C
(392 6 9°F).
7.2.2 Place a smooth, clean parting sheet on a backing plate
and center the chase on it. Put enough of the sample into the
cavity to fill it completely when molded. A slight excess of
material is desirable. Cover the loaded chase first with a clean
FIG. 1 Biaxial Ferris-Wheel-Type Rotator
parting sheet and then a backing plate. Finally, put the
assembled mold on the lower platen and close the press
carefully until both platens are in contact with the assembly.
When the material has melted, apply sufficient pressure to form
a void-free plaque in the 1.00 6 0.5 mm (0.039 6 0.002 in.)
thick and record this pressure. Leave the polypropylene in the
heated press under pressure for 3 to 4 min at 200 6 5°C (392
6 9°F). Flash cool the mold assembly by transferring to a
water-cooled press or by water quenching.
7.3 Injection Molding:
7.3.1 Plaques or test specimens shall be injection-molded in
accordance with the requirements of Specification D 4101.
7.4 Prepare a minimum of five specimens per material
sample by die-cutting specimens from the plaque or directly
molding the standard test specimen. The standard specimen
shall be 10 mm wide, 50 mm long, and 1.00 6 0.05 mm thick.
Edges shall be smoothed, if necessary, to remove imperfections
introduced by cutting.
7.5 Test specimens prepared directly by injection molding
without die cutting or specimens cut from polypropylene
products can be used as agreed upon between the interested
parties. In all cases the referee method will be based on
compression molded die cut specimens.
NOTE 4—Failure test times for compression-molded and injection-
molded specimens may vary due to the skin surface effect and the
distinctness or sharpness of the specimen edge.
7.6 Specimens of other thicknesses can be used as agreed
upon between the interested parties.
7.7 In cases of dispute, the referee specimens shall be
die-cut only from compression-molded specimens, unless the
test specimen is otherwise agreed upon.
7.8 In handling the plaques and cut specimens, use clean
FIG. 2 Uniaxially Rotated Specimen Holder—Drum Rotator
gloves or tongs to prevent contamination of the test specimens.
8. Conditioning
6.10 Anemometer, with a circular vane, for determining the
8.1 Condition the test specimens in accordance with Speci-
frequency of air changes in the oven. The anemometer shall be
fication D 4101. When unsure of the material formulation,
positioned directly in front of the oven outlet. Based on the
condition the test specimen at 23 6 2°C (73.4 6 3.6°F) and 50
design of the outlet and the anemometer, every effort shall be 6 5 % relative humidity for not less than 40 h prior to test in
D 3012
accordance with Procedure A of Practice D 618. In cases of 10.2 Attach the five specimens to the biaxial rotator by
disagreement, the tolerances shall be 61°C (61.8°F) and suitable metal clips lined with fluoropolymer film. Space the
62 % relative humidity. specimens 30 to 40 mm (1.2 to 1.6 in.) from each other on the
rack.
10.2.1 Avoid direct contact of the specimens with the metal
9. Oven Parameters
clips or metal parts. Certain metals, such as aluminum, are
9.1 Unless otherwise specified, the oven temperature shall
known to affect with the long-term thermal endurance of some
be 150°C (302°F) and shall not vary more than 61°C,
polypropylenes.
measured at a single location within the oven, or more than
10.3 Inspect the specimens at least once a day, turning off
61.5°C throughout the oven.
the biaxial rotator during inspection.
9.1.1 To monitor temperature, the oven temperature mea-
10.4 Failure by this test method is visual evidence of
surement sensor should be conveniently located about 80 mm
localized discoloration or crumbling on any part of the speci-
(3 in.)
...
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