What is Peel Adhesion test?


Peel Adhesion Test

The peel adhesion test is used to find out the load needed to de-bond two parts joined by an adhesive. The peel adhesion test result also called Bond strength, is usually shown as N (force to de-bond) / 25mm or 50mm (based on the test sample width). The components joints may be both flexible or one may be flexible while the other is rigid.

What is Peel Strength

Peel strength is the median load per unit width of bond line needed to slowly separate an elastic part from a stiff part over adhered surfaces. The angle among members differs with the type of peel test (T-peel90-degree peel180-degree peelfloating roller, or climbing drum). Peel strength quantities are stated in kilograms per millimeter (kg/mm) or pounds per inch of width.

Adhesion means to the strength of the adhesive or the sticky material to a substrate (the surface to which it sticks). It’s object-to-object interaction.

Cohesion is the strength of the adhesive itself or the strength of its own stickiness (not how well it sticks to a substrate).

Specification/ Standards for Peel Adhesion Test

Below is a list of ASMT peel test standards such as ASTM B533, C794, D1781, etc.

  • ASTM B533 Peel Metal Coating Test Equipment
  • ASTM C794 Adhesion-in-Peel Elastomeric Joint Sealants Test Equipment
  • ASTM D1781 Climbing Drum Peel Test Equipment for Adhesives
  • ASTM D1876 T Peel Resistance Test Equipment for Adhesives
  • ASTM D2979 Tack Adhesive Testing Machine
  • ASTM D3167 Peel Resistance Adhesives Test Equipment
  • ASTM D3330 – Peel Adhesion Pressure Sensitive Adhesive Tapes
  • ASTM D429 – Rubber to Metal Adhesion Test Equipment
  • ASTM D5170 T Peel Strength of Hook and Loop Touch Velcro Fasteners
  • ASTM D6252 90 Degree Peel Adhesion Equipment for Pressure-Sensitive Label Stocks
  • ASTM D6862 90 Degree Peel Resistance Test Equipment for Adhesives
  • ASTM D903 180 degree Peel Strip Strength of Adhesive Bonds
  • ASTM F88 Seal Strength Testing Equipment for Flexible Barrier Materials
  • ISO 4578 Peel Resistance Testing Adhesives
  • FTM-1 Peel adhesion (180 degrees) test equipment
  • PSTC-101 Peel Adhesion Test Equipment for Pressure-Sensitive Tape (PSA)

Type of Peel Adhesion Test

test surface
90 Degree and 180 Degree Peel Test

90 Degree peel test

During a 90-degree peel test, a constant 900 angle is maintained while the two adhesive-bonded components are peeled apart due to the applied force. The average load required to separate the two, over the length of the specimen
is documented and stated as N/25mm. Additional ways of expressing test results involve average peak/trough loads and customer-defined calculations. 

Test specimen requirement –5 specimens per set having size of 20 mm width and 200 mm length. Sample can be made directly from the part or from the test coupon. One of the two glued components should be flexible enough to be bent 900 without breaking.  

Test setup – The test specimen is clamped on a free-moving table. From one end of the specimen, either mechanically or chemically de-bond or separate the two components, 40mm in length. The separated top component is clamped in the moving vice, attached to a moving crosshead. 

The two components are peeled apart by the movement of the crosshead. The test speeds are normally 300mm/min or as per the standard. The free-moving table is attached to the crosshead using a pulley and rope mechanism, so that the traverse movement of the table is at the same rate as the crosshead movement, hence maintaining a constant 900 angle between the two components.

180 Degree peel test

During a 180 degree peel test, a constant 1800 angle is maintained while the two glued components are peeled apart from each other. The average load needed to separate the two, over the length of the specimen is documented and stated as N/25mm. Other methods of expressing test results include average peak/trough loads and customer-defined calculations. 

Sample requirement – 5 specimens per set having size of 20 mm width and 250 mm length. Sample can be made directly from the part or from the test coupon. One of the two glued components should be flexible enough to be bent 180 degrees without breaking.  

Test setup – The test specimen is clamped on a fixed grip. From one end of the specimen, either mechanically or chemically de-bond or separate the two components, 140mm in length. The separated top component is clamped in the moving vice, attached to a moving crosshead. 

The two components are peeled apart by movement of the crosshead. The test speeds are normally 300mm/min or as per the standard. The below diagram shows the test details:

Applications of Peel Adhesive Test

Peel adhesion testing is required for parts that are bonded together using adhesives for quality control and quality assurance. The application of peel adhesion test are:

  1. Quality control – To verify the glued parts required to meet a minimum specified bond strength value. 
  2. Adhesive curing – To find out the optimum temperature and pressure required to give the maximum bond strength on the components.
  3. Adhesive behavior – determine the effect of temperature, humidity and environmental conditions can have on the bond strength. 
  4. Quality assurance: where the glued parts need to ensure production quality.

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