Peel Strength Testing

Peel strength, the average force required to separate two bonded materials from one another, is a property applicable to various industries including aerospace, automotive, adhesives, packaging, biomaterials, microelectronics, and more. Peel test data is used to determine the quality of the adhesive joint and, where applicable, provides information on the effects of processes and of the environment on the adhesive-adherend interface strength.

How To Measure Peel Strength

Peel tests are constant-speed tests in the tensile direction. In material testing, peel strength is calculated after measuring and averaging the load to peel the specimen and dividing the average load by unit width of the bond line. The load data used in peel strength calculations is derived from the flat portion of the load vs. position curve. 

ASTM D3330 Test F, Load-Position curve generated on ADMET MTESTQuattro® software

Types of Peel Tests

A universal testing machine equipped with a peel fixture is used to perform peel tests. Simply by changing the fixturing, the same universal testing machine can be used to run various peel test methods. The main difference between these methods is the angle of peel. Common peel tests include:

• 45 degree peel tests
  • Most applicable to the food packaging industry
• 90 degree peel tests
  • Common peel test method run with the 90-degree peel fixture 
• 180 degree peel tests
  • Peel test method where the peel arms are clamped in the tensile grip jaws and pulled apart 
• 180 degree T-peel tests
  • Most commonly used with thin-gauge metal adherends
  • Lowest peel strength values 
• Climbing drum peel tests
  • Peel test setup to peel the specimen at a constant peel radius

Standard Peel Test Methods

Common peel testing standards include:

• ASTM D903 – Standard Test Method for Peel or Stripping Strength of Adhesive Bonds
• ASTM D1876 – Standard Test Method for Peel Resistance of Adhesives (T-Peel Test)
• ASTM D3167 – Standard Test Method for Floating Roller Peel Resistance of Adhesives
• ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape
• ASTM D6195 – Standard Test Methods for Loop Tack

Recommended Equipment

A universal testing machine equipped with the appropriate capacity load cell and peel fixturing (peel fixtures may vary depending on the type of peel test method followed) is required to run peel strength tests. We recommend the system to be controlled by a closed loop controller that can keep constant rate throughout the tests and have the ability to calculate the average peel strength data over a specified distance. Below is a featured product configuration for peel strength testing.