Effect of Flexing on the Barrier Properties of Metallized Films

One of the major concerns with respect to metallized films is the effect of flexing on their barrier properties. Films encounter a series of mechanical stress situations during manufacturing, processing, handling, and distribution. These mechanical stresses often result in flexing of the packaging film, which is more prominent with metallized films. The first part of my study evaluates the effect of real stresses of flex by using packages already manufactured and that have been through the distribution cycle. Metallized film samples from these packages were tested to see the effect of real stress on their barrier properties. The results showed an increase in the oxygen transmission rates and water vapor transmission rates of the flexed samples indicating that flexing decreases the barrier properties of metallized films. Flexing leads to the initiation of pinholes that subsequently lead to a loss in barrier properties. The second part of my study evaluates whether the Gelbo flex tester simulates the actual distribution environment encountered by flexible packages. The metallized films were submitted to 10, 50 and 100 full flex cycles on a Gelbo flex tester and their permeation rates were evaluated comparatively. The results showed that for different films, different numbers of flex cycles are required to simulate mechanical stress during processing and distribution