Designation: D1876 – 08
Standard Test Method for
Peel Resistance of Adhesives (T-Peel Test)1
This standard is issued under the fixed designation D1876; 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.
This standard has been approved for use by agencies of the Department of Defense.
INTRODUCTION
The accuracy of the results of strength tests of adhesive bonds will depend on the conditions under
which the bonding process is carried out. Unless otherwise agreed upon by the manufacturer and the
purchaser, the bonding conditions shall be prescribed by the manufacturer of the adhesive. In order to
ensure that complete information is available to the individual conducting the tests, the manufacturer
of the adhesive shall furnish numerical values and other specific information for each of the following
variables:
(1) Procedure for preparation of the surfaces prior to application of the adhesive, the cleaning and
drying of metal surfaces, and special surface treatments such as sanding, which are not specifically
limited by the pertinent test method.
(2) Complete mixing directions for the adhesive.
(3) Conditions for application of the adhesive, including the rate of spread or thickness of film,
number of coats to be applied, whether to be applied to one or both surfaces, and the conditions of
drying where more than one coat is required.
(4) Assembly conditions before application of pressure, including the room temperature, length of
time, and whether open or closed assembly is to be used.
(5) Curing conditions, including the amount of pressure to be applied, the length of time under
pressure, and the temperature of the assembly when under pressure. It should be stated whether this
temperature is that of the glue line, or of the atmosphere at which the assembly is to be maintained.
(6) Conditioning procedure before testing, unless a standard procedure is specified, including the
length of time, temperature, and relative humidity.
A range may be prescribed for any variable by the manufacturer of the adhesive, if it can be assumed
by the test operator that any arbitrarily chosen value within such a range or any combination of such
values for several variables will be acceptable to both the manufacturer and the purchaser of the
adhesive.
1. Scope
1.1 This test method is primarily intended for determining
the relative peel resistance of adhesive bonds between flexible
adherends by means of a T-type specimen.
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are provided for
information purposes only.
1.3 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:2
B209 Specification for Aluminum and Aluminum-Alloy
Sheet and Plate
D907 Terminology of Adhesives
3. Terminology
3.1 Definitions—Many terms in this test method are defined
in Terminology D907.
1 This test method is under the jurisdiction of ASTM Committee D14 on
Adhesives and is the direct responsibility of D14.80 on Metal Bonding Adhesives.
Current edition approved Oct. 1, 2008. Published October 2008. Originally
approved in 1961. Last previous edition approved in 2001 as D1876 – 01. DOI:
10.1520/D1876-08.
2 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.
1
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3.1.1 peel strength, n—the average load per unit width of
bondline required to separate progressively a flexible member
from a rigid member or another flexible member.
3.1.1.1 Discussion—Flexible has different meanings in dif-
ferent peel tests, such as “T,” 180-degree, floating-roller, or
climbing-drum. The angle between the members varies with
the type of peel test.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 flexible, adj—indicates that the adherends shall have
such dimensions and physical properties as to permit bending
them through any angle up to 90° without breaking or cracking.
3.2.2 T-peel strength, n—the average load per unit width of
bond line required to produce progressive separation of two
bonded, flexible adherends, under conditions designated in this
test method.
4. Apparatus
4.1 Tension Testing Machine, capable of applying a tensile
load having the following prescribed conditions:
4.1.1 The machine and loading range selected that the
maximum load on the specimen falls between 15 and 85 % of
the upper limit of the loading range.
4.1.2 The rate of movement between heads essentially
constant under fluctuating loads.
NOTE 1—It is difficult to meet this requirement when loads are
measured with a spring-type or pendulum-type weighing device.
4.1.3 The machine equipped with suitable grips capable of
clamping the specimens firmly and without slippage through-
out the tests.
4.1.4 The machine shall be autographic, giving a chart that
can be read in terms of inches of separation as one coordinate
and applied load as the other coordinate.
4.1.5 The applied tension as measured and recorded accu-
rate to 61 % of any reading when calibrated in compliance
with Practices requirements.
4.2 Conditioning Room or Desiccators—The conditioning
room or desiccators (Note 2) shall be capable of maintaining a
relative humidity of 50 6 2 % at 23 6 1°C (73.4 6 1.8°F).
NOTE 2—A saturated solution of calcium nitrate will give approxi-
mately 51 % relative humidity at the testing temperature.
5. Test Specimen
5.1 Laminated test panels (see Fig. 1) consist of two flexible
adherends properly prepared and bonded together in accor-
dance with the adhesive manufacturer’s recommendations.
Specially prepared test panels 152 mm (6 in.) wide by 305 mm
(12 in.) long, but bonded only over approximately 241 mm (9
in.) of their length. Test panels of these same dimensions may
also be cut from larger, fully laminated panels.
NOTE 3—Direct comparisons of different adhesives can be made only
when specimen construction and test conditions are identical.
NOTE 4—Clad aluminum alloy 0.81 mm (0.032 in.) thick conforming to
Specification B209, Alloy 2024-T3, has been found satisfactory as an
adherend for structural adhesives. Canvas, coated fabrics, plastics films,
and metal foils have also proven to be satisfactory adherends for use with
specific adhesives.
NOTE 5—It is not essential that the two adherends be alike, either in
material or thickness. They shall, however, be capable of being bent
through any angle up to 90° without breaking.
5.2 Cut the bonded panels into 25-mm (1-in.) wide test
specimens (see Fig. 1) by a means that is not deleterious to the
bond. The 76-mm (3-in.) long unbonded ends bent apart,
perpendicular to the glue line, for clamping in the grips of the
testing machine.
5.3 Test at least ten specimens for each adhesive.
NOTE 6—Within the limitations imposed by Note 3, other specimen
widths may be used, provided the test machine grips are of ample width
to apply the load uniformly across the width of the adherends.
NOTE 7—For obtaining a gripping area on specimens that are com-
pletely bonded, one end of the bonded specimen may be chilled in dry ice
until the adhesive becomes brittle, and then the adherends may be
carefully pried apart. The technique will not work for all adhesives and
adherends.
6. Conditioning
6.1 Condition specimens for 7 days at a relative humidity of
50 6 2 % at 23 6 1°C (73.4 6 1.8°F), except where the
adhesive manufacturer may specify such an aging period to be
unnecessary or a shorter period to be adequate.
FIG. 1 Test Panel and Test Specimen
D1876 – 08
2
NOTE 8—Conditioning is not required for laminated assemblies con-
taining only metal adherends, unless specified as a part of the bonding
procedure by the manufacturer of the adhesive.
7. Procedure
7.1 Clamp the bent, unbonded ends of the test specimen in
the test grips of the tension testing machine. Apply the load at
a constant head speed of 254 mm (10 in.)/min.
NOTE 9—This speed will cause separation of the bond at a rate of 127
mm (5 in.)/min.
7.2 During the peel test make an autographic recording of
load versus head movement or load versus distance peeled.
7.3 Determine the peel resistance over at least a 127-mm
(5-in.) length of the bond line after the initial peak.
8. Calculation
8.1 Determine from the autographic curve for the first 127
mm (5 in.) of peeling after the initial peak the average peeling
load in pounds per inch of the specimen width required to
separate the adherends. It is preferred that the average to be
determined from the curve with the use of a planimeter.
NOTE 10—In case a planimeter is not used, the average may be
calculated as the average of load readings taken at fixed increments of
crosshead motion. For example, the load may be recorded at each 25-mm
(1-in.) interval of head motion (or each 12.7-mm (0.5-in.) interval of bond
separation) following the initial peak, until at least ten readings have been
obtained.
9. Report
9.1 Report the following information:
9.1.1 Complete identification of the adhesive tested, includ-
ing type, source, manufacturer’s code number, batch or lot
number, form, etc.,
9.1.2 Complete identification of adherends used, including
material, thickness, surface preparation, and orientation,
9.1.3 Description of bonding process, including method of
application of adhesive, glue-line thickness, drying or precur-
ing conditions (where applicable), curing time, temperature,
and pressure,
9.1.4 Average thickness of adhesive layer after formation of
the joint, within 0.025 mm (0.001 in.). The method of
obtaining the thickness of the adhesive layer shall be described
including procedure, location of measurement, and range of
measurements.
9.1.5 Complete description of the test specimens, including
dimensions and construction of the test specimens, conditions
used for cutting individual test specimens, number of test
panels represented, and number of individual test specimens,
9.1.6 Conditioning procedure prior to testing,
9.1.7 Type of test machine and crosshead separation rate
used,
9.1.8 Method of recording load and determining average
load,
9.1.9 Average, maximum, and minimum peeling load values
for each individual specimen,
9.1.10 Average T-peel strength in pounds per inch of width
for each combination of materials and constructions under test,
and
9.1.11 Type of failure, that is, cohesive failure within the
adhesive or adherend or adhesion to the adherend, or combi-
nation thereof, for each individual specimen (see Terminology
D907).
10. Precision and Bias
10.1 Precision and bias for this test method is being devel-
oped and will be available by December 2010.
11. Keywords
11.1 adhesive bonding; flexible adherends; T-peel strength
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D1876 – 08
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Scope
Referenced Documents
Terminology
Apparatus
Test Specimen
Conditioning
FIG. 1
Procedure
Calculation
Report
Precision and Bias
Keywords