ASTM F88
Seal Strength of Plastic Films
When it comes to packaging materials, ensuring that seals maintain their strength during transport and storage is critical. ASTM F88, a standard test method for the seal strength of flexible barrier materials, provides essential guidelines for accurately measuring the seal strength of flexible films. In industries such as food, medical, and pharmaceutical packaging, it is vital to confirm that seal integrity meets required standards to ensure product safety and quality.
ASTM F88 - The Seal Strength Standard for Packaging Materials
ASTM F88 provides a standardized method for determining the seal strength of plastic films, such as plastic films used in packaging. This test is essential for process validation, process control, and ensuring packaging integrity during handling and transportation. The test focuses on the ability of sealed films to resist forces that may compromise the seal during real-world conditions.
The significance of seal strength extends beyond the ability to keep a package closed. A properly sealed package prevents contamination, moisture intrusion, and ensures the product inside maintains its integrity. This test method also plays a crucial role in determining the opening force of seals. For certain applications, it may be advantageous to limit the strength of the seal to ensure easy access for consumers while maintaining sufficient barrier protection.
Key Factors in Seal Strength Measurement According to ASTM F88
ASTM F88 outlines several key factors that influence the accuracy of seal strength testing:
The test requires the preparation of sealed specimens, where the seals are subject to tension until failure. Specimens are cut to specific dimensions, ensuring consistency in the test procedure. The dimensions of the seal area and sample size may vary depending on the material being tested, with the standard recommending precise control over the specimen’s cut and seal.
ASTM F88 defines several test techniques for preparing specimens, such as unsupported, hand-supported, and rigidly supported samples. Each technique helps isolate variables such as bending forces that can influence the seal strength. Standardized usage of these techniques ensures comparability across tests.
To measure seal strength accurately, the test requires a tensile testing machine that can measure the force required to break the seal. The machine must have an adjustable rate of separation between grips and a consistent force measurement system. A modern tensile testing machine with a digital interface is recommended for precision in data recording and analysis.
ASTM F88 Application - Heat Seal Strength Testing
One of the most critical applications of ASTM F88 is in heat seal strength testing for plastic films. This method tests how well a heat-sealed package holds together under tensile, an important factor in packaging design and manufacturing.
Heat seal strength testing involves applying heat and pressure to join plastic films. During testing, various factors such as temperature, pressure, and sealing time must be carefully controlled to ensure consistent results. The Heat Seal Tester from Cell Instruments are excellent tools for this type of testing. These devices allow precise control over sealing conditions, ensuring that each test is carried out with accuracy and repeatability.
Interpreting Heat Seal Strength Testing Results
Once the heat seal test is completed, the tensile testing machine records the maximum force exerted before the seal breaks. The data is used to evaluate the heat seal’s integrity and performance. The failure mode of the specimen—whether the seal fails cohesively, adhesively, or through delamination—also provides important insights into the seal’s quality.
If the test strip peels apart in the seal area, this can indicate adhesive failure or delamination, requiring further examination. In some cases, the average peel force may be the most important measure of seal strength. The results guide manufacturers in adjusting their sealing processes to achieve the desired level of strength and durability.