ASTM D2148-22

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
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Designation: D2148 − 19 D2148 − 22
Standard Test Methods for
Bondable Silicone Rubber Tapes Used for Electrical
Insulation
This standard is issued under the fixed designation D2148; 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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Adjunct information was updated editorially in January 2021.
1. Scope*
1.1 These test methods cover tests for bondable silicone rubber tapes which form a sealed structure either with the application of
heat (and pressure if needed) or by the process of auto-adhesion (self-fusing).
1.2 These test methods appear in the following sections:
Test Method Section
Adhesion 3 – 10
Bond Strength 11 – 18
Dielectric Breakdown Voltage 19 – 26
Hardness 41
Length 33 and 34
Thickness 27 – 32
Width 36 – 40
1.3 Units—The values stated in SI units are the standard. The inch-pound units in parentheses are for information only. The values
stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall
be used independently of the other, and values from the two systems shall not be combined.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For a specific hazard statement see 23.1.1.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D374/D374M Test Methods for Thickness of Solid Electrical Insulation
These test methods are under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and are the direct responsibility of Subcommittee
D09.07 on Electrical Insulating Materials.
Current edition approved Aug. 1, 2019Oct. 1, 2022. Published August 2019October 2022. Originally approved in 1963. Last previous edition approved in 20182019 as
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D2148 – 18.D2148 – 19 . DOI: 10.1520/D2148-19E01.10.1520/D2148-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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
D2148 − 22
D618 Practice for Conditioning Plastics for Testing
D1000 Test Methods for Pressure-Sensitive Adhesive-Coated Tapes Used for Electrical and Electronic Applications
D1458 Test Methods for Fully Cured Silicone Rubber-Coated Glass Fabric and Tapes for Electrical Insulation (Withdrawn
2019)
D2240 Test Method for Rubber Property—Durometer Hardness
2.2 ASTM Adjuncts:
Tack Tester (one drawing)
ADHESION
3. Scope
3.1 This test method covers the determination of the self-adhesion of unsupported, self-fusing silicone rubber rectangular and
taper-edge (Note 1) tape designed for use as electrical insulation.
NOTE 1—Taper-edge tape includes such cross sections as triangular, lens, etc.
3.2 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Scope
3.1 This test method covers the determination of the self-adhesion of unsupported, self-fusing silicone rubber rectangular and
taper-edge (Note 1) tape designed for use as electrical insulation.
NOTE 1—Taper-edge tape includes such cross sections as triangular, lens, etc.
4. Hazards
4.1 High Voltage:
4.1.1 Lethal voltages are a potential hazard during the performance of this test. It is essential that the test apparatus, and all
associated equipment electrically connected to it, be properly designed and installed for safe operation.
4.1.2 Solidly ground all electrically conductive parts which it is possible for a person to contact during the test.
4.1.3 Provide means for use at the completion of any test to ground any parts which were at high voltage during the test or have
the potential for acquiring an induced charge during the test or retaining a charge even after disconnection of the voltage source.
4.1.4 Thoroughly instruct all operators as to the correct procedures for performing tests safely.
4.1.5 When making high voltage tests, particularly in compressed gas or in oil, it is possible for the energy released at breakdown
to be sufficient to result in fire, explosion, or rupture of the test chamber. Design test equipment, test chambers, and test specimens
so as to minimize the possibility of such occurrences and to eliminate the possibility of personal injury. If the potential for fire
exists, have fire suppression equipment available. See 23.1
5. Significance and Use
5.1 Self-adhesion is a primary initial property since it affects layer-to-layer bonding. The integrity of the bond can significantly
affect the electrical and physical performance of the insulation system. Therefore, the degree of self-adhesion is directly related
to apparatus performance.
5.2 A high degree of self-adhesion is desirable for most electrical applications. In this test, a short unwinding length indicates a
high degree of self-adhesion.
The last approved version of this historical standard is referenced on www.astm.org.
D2148 − 22
5.3 This test method has been found useful as a quality control test for lot acceptance.
6. Apparatus
6.1 Inclined Mandrel Tack Test Fixture—A suggested fixture is shown in Fig. 1. Tack tester assembly and details are included as
Appendix X1. The mandrel shall consist of a 16 mm (0.625 in.) diameter aluminum rod mounted in low-friction bearings. Good
alignment of bearings is necessary for accurate results. When properly assembled, the mandrel shall turn freely when loaded with
a 28 g (1-oz) weight suspended from a cotton thread wound in a single layer at the center of the mandrel.
6.2 Weights, as specified in Section 8 and means for attachment.
6.3 Calibrated stopwatch capable of measuring accurately to one second.
7. Test Specimen
7.1 A test specimen shall consist of two pieces of tape 305305 mm to 380 mm (12 to 15 in.) long. Divisions spaced 25 mm (1
in.) apart shall be marked off on one piece of tape. If tapes contain an interliner, the interliner shall be removed just prior to
wrapping the mandrel. Dirt and other forms of contamination shall be avoided.
8. Procedure
8.1 Winding—Half lap the unmarked specimen perfectly on the mandrel of the test fixture, using the suggested weight as shown
in Table 1. These weights are not critical. However, they are necessary to get intimate contact and conformability of the tape. To
obtain perfect half lapping, tilt the tack tester at an appropriate angle as shown in Fig. 1. Wrap the tape on the mandrel at a speed
of approximately 460 mm (18 in.)/min. Using the winding procedure and weights just described, half lap the marked tape sample
on the mandrel over the first piece of tape. With the winding weight attached, return the test fixture to a horizontal position and
allow the tape to bond for 1 min. Remove the winding weight from the tape and the handle from the fixture and proceed with the
unwinding test.
8.2 Unwinding—After the tape has bonded for 1 min, attach a load of 600 g (21 oz)/25 mm (in.) of the original tape width (Note
2). Attach the weight to the free end of the tape by means of a bulldog paper clamp or other suitable device. Release the weight
and record the length of tape unwound in 3 min. Although the original 25 mm (1 in.) dimensions will elongate due to the unwind
weight, consider each division as one unit. While the winding weights are not critical, the use of proper unwinding weights is
mandatory. Consistent and comparable results depend upon accurate width measurements and the use of the proper unwinding
weight.
FIG. 1 Inclined Mandrel Tack Test Fixture
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TABLE 1 Suggested Winding Weights for 1-in. Wide Tapes
Note—Winding weights are based on cross-sectional area and have been
selected to produce approximately the same unit stress on all cross-sections.
For tapes of dimensions not listed, use a winding weight of approximately
2 2
300 g (10.5 oz)/6 mm (0.01 in. ).
Tape Thickness, mm (in.)
Weight, g (oz)
Triangular Rectangular
0.50 (0.020) 0.25 (0.010) 300 (10.5)
0.75 (0.030) 0.4 (0.015) 450 (15.8)
1.02 (0.040) 0.5 (0.02) 600 (21.0)
1.27 (0.050) 0.64 (0.025) 750 (26.4)
1.52 (0.060) 0.76 (0.030) 900 (31.7)
1.78 (0.070) . 1050 (37.0)
2.03 (0.080) . 1200 (42.3)
NOTE 2—Commercial tapes are usually made to a 61.6 mm (60.06 in.) tolerance. Therefore a 600-g weight shall be used for tapes varying in width from
2424 mm to 27 mm (0.94 to 1.06 in.); a 750-g weight shall be used for tapes varying in width from 3030 mm to 33 mm (1.19 to 1.31 in.) and a 900-g
weight shall be used for tapes varying in width from 3737 mm to 40 mm (1.44 to 1.56 in.). Tapes with widths outside these ranges shall be tested in
accordance with their width (determined to the nearest 1.6 mm (0.06 in.). For example, a 29 mm (1.125 in.) wide tape shall be tested with a 675-g weight.
The unwinding weights shall be made to a tolerance of 62 %.
9. Report
9.1 Report the following information:
9.1.1 Description of material, type of cross-section, tape width and thickness,
9.1.2 Winding weight, in grams,
9.1.3 Unwinding weight, in grams, and
9.1.4 Length of unwind, to the nearest ⁄4 unit.
10. Precision and Bias
10.1 This test method has been in use for many years, but no information has been presented to ASTM upon which to base a
statement of precision. No activity has been planned to develop such information.
10.2 This test method has no bias because the value for adhesion is determined solely in terms of this test method itself.
BOND STRENGTH
11. Terminology
11.1 Definitions of Terms Specific to This Standard:
11.1.1 bond strength, of unvulcanized and semivulcanized supported silicone rubber tapes—the strength of chemical linkages
achieved between successive layers of tape under controlled vulcanizing conditions.
12. Significance and Use
12.1 The bond strength is an indication of the physical integrity that can be expected under end use conditions in which the
insulating tapes are applied with an overlap.
13. Apparatus
13.1 Bonding Press—A platen press having the following characteristics:
13.1.1 A temperature range to 205 °C (400 °F).
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13.1.2 A thermostat that will allow a set temperature to be maintained 6 5 °C (6 9 °F).
13.1.3 A pressure regulator to allow setting and control of the platen pressure.
13.1.4 A pressure indicator to show the pressure being exerted between the platen faces.
13.1.5 A timer to allow measurement of bonding time. It is preferred that a controller-type timer be used which will both indicate
bonding time and also cause the platen pressure to be released and the platens separated at the end of the bonding period.
13.2 Temperature-Measuring Device(s) to indicate face temperature of the platen(s).
13.3 Silicone Rubber Pad, approximately 3.2 mm (0.125 in.) thick, 60 to 70 Shore A durometer hardness, larger in dimension than
the specimens to be tested. This is used as a pressure-equalizing device, compensating for irregularities in either the specimen or
the platens.
13.4 Polytetrafluoroethylene or suitable release film, three sheets, approximately 0.050.05 mm to 0.10 mm (2 to 4 mils) thick. One
sheet is placed on each side of the specimens as a release sheet, the third sheet being used to separate the ends of the two test
specimens.
13.5 Testing Machine—A power-driven testing machine of either the cross head or dead-weight pendulum type. The machine shall
be equipped with a tension weighing device having a maximum capacity of 22.7 kg (50 lb) graduated to read 50 g (0.1 lb) or less
per scale division.
14. Test Specimen
14.1 The test specimen shall be selected to be representative of the material to be tested. The size of sample shall be sufficient
to give six strips at least 3232 mm to 38 mm (1.25 to 1.5 in.) wide and 150 mm (6 in.) long. Care shall be taken to prevent
contamination.
15. Conditioning
15.1 The specimen shall not be exposed to temperatures above 30 °C (85 °F) before bonding. The tests shall be conducted in the
Standard Laboratory Atmosphere as described in Practice D618.
16. Procedure
16.1 Cut the strips of material to 3232 mm to 38 mm (1.25 to 1.5 in.) wide and at least 150 mm (6 in.) long, the length being
measured in the warp or machine direction of the backing.
16.2 Remove any interliner material.
16.3 Superimpose one strip on another, front side to back side, to form a specimen.
16.4 Separate the two strips at one end for a distance of about 25 mm (1 in.) and insert a strip of release film.
16.5 Preheat the pres
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