Standard Test Method for Seal Strength of Flexible Barrier Materials (Peel Test)
ASTM F88 is the standard followed when performing Peel tests on Packaging. Peel Tests determine ‘Seal strength’ of the package, which is defined as the measure of the ability of a package seal to resist separation. The test results are not only related to package integrity, but also to measuring the packaging processes' ability to produce consistent seals. Given that Seal strength is a necessary requirement for packaging, Peel Tests are ubiquitous for all types of packaging.
According to the ASTM F88 standard, a number of fixtures and techniques have been devised to hold samples at various angles to the pull direction to control this bending force. Because the effect of each of these on test results is varied, consistent use of one technique (Technique A, Technique B, or Technique C) throughout a test series is recommended.
Descriptions and examples of fixtures and techniques from the standard are illustrated in figure below:
- Technique A: Unsupported—Each tail of the specimen is secured in opposing grips and the seal remains unsupported while the test is being conducted. This is the method used by MPT.
- Technique B: Supported 90° (By Hand)—Each tail of the specimen is secured in opposing grips and the seal remains hand-supported at a 90° perpendicular angle to the tails while the test is being conducted.
- Technique C: Supported 180°—The least flexible tail is supported flat against a rigid alignment plate held in one grip. The more flexible tail is folded 180° over the seal and is held in the opposing grip while the test is being conducted.
- 1.1 This test method covers the measurement of the strength of seals in flexible barrier materials.
- 1.2 The test may be conducted on seals between a flexible material and a rigid material.
- 1.3 Seals tested in accordance with this test method may be from any source, laboratory or commercial.
- 1.4 This test method measures the force required to separate a test strip of material containing the seal. It also identifies the mode of specimen failure.