Paper coatings, plastic films and foils are examples of some of the many materials used as lidding mechanisms for packaging applications in a variety of industries. Barrier properties, seal strength, peel strength, and shelf life as well as many other characteristics are affected by the materials used as sealing lids. The amount of force required to open a lid (seal strength) is extremely important for end-use usability and for product security.
A manufacturer of food trays was interested in measuring the seal strength of their products for many of the reasons mentioned above, and asked us for a testing configuration recommendation. Using an Instron electromechanical test frame, a 180 degree peel test was conducted to measure the initial peel strength. We used an Instron model 3345 single column test frame configured with a 500N load cell and 1kN side acting pneumatic grips to perform testing on both full trays and on one inch wide cut strips to attain repeatable results. The initial peel strength was measured by peeling the lid back from the corner of the part by gripping onto the removal tabs. In order to be able to fit the specimen between the grips with minimum grip contact, the grip faces were attached vertically. The test was run at a crosshead speed of 200 mm/min until the lid was completely removed.