ASTM D1781 Climbing Drum Peel for Adhesives

The ASTM D1781 test method determines the peel resistance of adhesive bonds between two materials with different physical properties. It measures the peel resistance between: ❖ a relatively flexible adherend and a rigid adherend ❖ a relatively flexible facing of a sandwich structure and its core.

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Scope:

ASTM D1781 is a standard test method for determining the adhesive bond peel resistance on items with a flexible adherend and a rigid adherend surface. By removing the sandwich assembly’s face, this standard can also be used to examine the structure and core of a sandwich. The purpose is to determine how much torque is needed to peel the two materials. The ASTM D1781 test is most commonly used in A-B comparison testing, which compares the outcomes of two alternative process conditions in order to improve a process. For moderately brittle adhesives, peel resistance may also indicate the degree of cure.

Procedure:

The climbing drum peel fixture with the specimen is put in the test frame for the ASTM D1781 test process. The average peeling load between 1 inch and 6 inches of adherend separation is determined by applying a tensile force at a constant rate of crosshead separation. The amount of crosshead movement required is determined by the ascending drum peel fixture’s shape. A standard formula is used to calculate the average peeling torque or average peeling load.

Specimen size:

As per the ASTM D1781 test method:

➢ For evaluation of adhesives in laminated assemblies, the specimen is 25 mm wide between saw kerfs and at least 254 mm long.

➢ For evaluation of adhesives in sandwich constructions, the specimen is 76 mm wide and at least 305 mm (12 in.) long.

Data :

According to the ASTM D1781 test, the average peel torque, T, is calculated as follows. T=[(R-r)(F-f)]/W]

where,

T = average peel torque, mm.kg/mm of width

R = radius of the flange, including one half the thickness of the loading straps, in mm

r = radius of the drum plus one half the thickness of the adherend being peeled, in mm

F = average load required to bend and peel the adherend plus the load required to overcome the resisting torque, kg

f = load required to overcome the resisting torque, in pound and

w = width of the specimen, in mm

Conclusion:

ASTM D1781 is a standard test method for determining the adhesive bond peel resistance on items with a flexible adherend and a rigid adherend surface.