Seal strength is related to the pack opening force and a measure of the consistency of the packaging process. The maximum seal force, average peel force and total energy absorbed in peeling the seal can be recorded.
The strength of seals in flexible barrier materials is also routinely measured as part of the validation exercise on medical device packaging. Seal strength tests are typically performed on pouches and lidded trays as a measure of heat seal quality.
Dynamic seal strength testing is made in accordance with ASTM F88.
The resistance to log term creep separation of the seal is assessed using a static loading.
Smithers Pira is UKAS accredited for testing to ASTM F88.
Lidding film peel strength
The seal strength of the lidding on semi-rigid packs is a balance between consumer ease of opening and the retention of pack integrity.
Smithers Pira is able to test the mechanical seal strength of lidding films in accordance with ASTM F2824. The force required to separate the lid from the container is continuously measured as the lid is peeled at a constant 45° angle to simulate consumer opening of the pack.
The 45° peel test is applicable to a variety of containers with flexible lids including, rigid thermoformed cups, injection-moulded cups and single serve containers.
In conjunction with integrity testing, it may be used in the validation of the sterile barrier system requirements of ISO 11607-2 for medical devices.
Smithers Pira is UKAS accredited for testing to ASTM F2824 and ISO 11607-2.