ASTM D411-98
(Test Method)Standard Test Methods for Shellac Used for Electrical Insulation
Standard Test Methods for Shellac Used for Electrical Insulation
SCOPE
1.1 These test methods cover tests for shellac in the dry button or powder form to be used for electrical insulating purposes. Typically, shellac is used as a bonding agent for mica splittings and reconstituted mica paper products, or as a coating or adhesive for other material.
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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 411 – 98 An American National Standard
Standard Test Methods for
Shellac Used for Electrical Insulation
This standard is issued under the fixed designation D 411; 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 4.7 Ash, and
4.8 Orpiment (Native arsenic trisulfide).
1.1 These test methods cover tests for shellac in the dry
button or powder form to be used for electrical insulating
POLYMERIZATION TIME
purposes. Typically, shellac is used as a bonding agent for mica
splittings and reconstituted mica paper products, or as a coating
5. Significance and Use
or adhesive for other material.
5.1 Polymerization time provides a measure of time during
1.2 This standard does not purport to address all of the
which shellac retains its plasticity and flow properties at the
safety concerns, if any, associated with its use. It is the
specified temperature before gelling or polymerizing to the
responsibility of the user of this standard to establish appro-
tough rubbery insoluble form. This test is important in deter-
priate safety and health practices and determine the applica-
mining the quality of different lots, useful shelf-life, batch
bility of regulatory limitations prior to use.
uniformity, and processing characteristics of shellac.
NOTE 1—There is no similar or equivalent IEC standard.
6. Apparatus
2. Referenced Documents
6.1 Test Tubes and Wire Rack—Two 18-mm outside diam-
2.1 ASTM Standards: eter glass test tubes, supported by a wire rack to a depth of 100
D 29 Test Methods for Sampling and Testing Lac Resins mm when placed in an oil bath. The test tubes must be
D 1711 Terminology Relating to Electrical Insulation supported and maintained in a vertical position. The rack shall
D 5032 Practice for Maintaining Constant Relative Humid- be constructed so as to permit free circulation of oil around the
ity by Means of Aqueous Glycerine Solutions test tubes.
D 6054 Practice for Conditioning Electrical Insulating Ma- 6.2 Oil Bath—The oil bath shall be constructed with heat-
terials for Testing ers, temperature control, and means of circulation to maintain
E 104 Practice for Maintaining Constant Relative Humidity the oil or other liquid at a temperature of 150 6 1°C at all
by Means of Aqueous Solutions points within the bath. The oil or other liquid used shall be
appropriate for the design of the bath and for safety at the test
3. Terminology
temperature. The bath shall be equipped with a thermometer, or
3.1 Definitions: For definitions of terms used in this stan- other indicator or recorder, to indicate the oil temperature
dard, refer to Terminology D 1711.
within 61°C.
6.3 Glass Rod—A smooth glass rod about 3 mm in diameter
4. General Tests
and approximately 200 mm long. The end of the glass rod
4.1 Each of the following tests shall be made in accordance
which is to be immersed in the shellac shall be fire polished to
with the procedures described in Test Methods D 29:
a smooth round end.
4.2 Sampling,
NOTE 2—A smooth glass rod about 5 mm in diameter and approxi-
4.3 Insoluble Matter,
mately 200 mm long with an indicator mark at the top to indicate
4.4 Iodine Number,
movement may be used. Flatten slightly the diameter of the glass rod for
4.5 Moisture Content,
approximately 3 mm length at the end which is immersed in the shellac.
4.6 Wax, The purpose of the flattened rod is to provide a more positive feel of the
twist back and rubbery character at the end point. If this alternative is
used, it must be specified in the report.
These methods are under the jurisdiction of ASTM Committee D-9 on
6.4 Timer, for indicating elapsed time in minutes and
Electrical and Electronic Insulating Materials and are the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders, and Encapsu-
seconds.
lating Compounds.
Current edition approved Nov. 10, 1998. Published January 1999. Originally
7. Test Specimens
published as D 411 – 35 T. Last previous edition D 411 – 94.
Annual Book of ASTM Standards, Vol 06.03. 7.1 For each test specimen use 4.00 6 0.01 g of shellac,
Annual Book of ASTM Standards, Vol 10.01.
dried as specified in 8.2.
Annual Book of ASTM Standards, Vol 10.02.
7.2 Prepare two specimens from each sample.
Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D411
8. Conditioning herein. These methods consist of melting a specimen of ground
shellac in a graduated test tube and then tilting the tube to a
8.1 Crush samples of shellac on clean paper, mix well, and
specified angle while maintained at 1006 1°C in order to
then dry as described in 8.2.
permit the shellac to flow down the tube.
8.2 For each sample to be tested, evenly spread 9 to 10 g of
13.2 Two methods are provided as follows:
the sample in a flat-bottom dish about 50 mm in diameter.
13.2.1 Method A—In this method the time required for the
Desiccate over anhydrous calcium chloride for at least 24 h at
shellac to flow specified distances along the test tube is
room temperature, or dry in a forced-convection oven at a
measured, and
temperature of 40 6 2°C for 16 to 20 h.
13.2.2 Method B—In this method the total distance the
8.3 After drying, immediately transfer the sample to a clean,
shellac flows along the test tube in a specified time is
dry, tightly stoppered bottle, and allow to cool. Do not open the
measured.
bottle except when a specimen is being removed for test.
14. Significance and Use
9. Procedure
14.1 The rate at which shellac flows down an inclined plane
9.1 Transfer a specimen of shellac from the stoppered bottle
under standard conditions can be used to determine the flow
to the 18-mm glass test tube. Insert the tube and hold securely
variation that occurs between different types, grades, or lots of
in a vertical position in the test rack. Place the rack in the oil
shellac.
bath having a test temperature of 150 6 1°C maintained
14.2 Flow tests are sensitive to atmospheric conditions, the
throughout the test.
flow being greater under humid conditions, and less with low
9.2 Start the timer when the test tube enters the oil bath.
humidity. It is essential to carry out the tests in a conditioned
9.3 Using the glass rod, stir the specimen gently until the
atmosphere or as quickly as possible after removal from the
specimen melts, but not for more than 3 min. Do not stir after
conditioning atmosphere so as to minimize errors due to the
3 min.
effects of atmospheric conditions.
9.4 Beginning 4 min after immersion of the test tube, and at
15. Apparatus
the end of each subsequent minute, give the glass rod a slight
twist, turning approximately 90° each time. In the early stages
15.1 Suitable apparatus for both Methods A and B are
of the test, and before the polymerization point is reached, the
described in Annex A1.
glass rod will remain in the position to which it has been
15.2 Any apparatus that will provide for accurate tempera-
turned. When, however, the shellac takes on a rubbery set,
ture control, correct positioning of the test tubes, and for visual
there will be a definite turning or twisting back of the rod
observation of flow when required may be used.
following the 90° twist. This is the end point.
16. Conditioning
NOTE 3—In the early stages of the test there may be a tendency for the
16.1 For each specimen use 2.0 6 0.1 g of shellac, ground
glass rod to move back slowly after twisting with the fingers. This slight
to pass a No. 20 sieve. Prepare two specimens from each
movement should not be confused with the definite “twist-back” observed
sample.
when the end point is reached.
16.2 Spread the specimens out in shallow vessels. Condition
10. Polymerization Time
for at least 24 h in a standard laboratory atmosphere in
accordance with Practice D 6054. Alternatively, condition for
10.1 Record as the polymerization
...
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