Meaning
Specialized laboratory testing apparatuses isolate and evaluate chemical migration from only one side of a polymer film or sheet. During regulatory testing for multi-layer films, a single side migration cell ensures that only the food-contact layer is exposed to the food simulant. This is critical when the outer layer contains inks or adhesives that would skew the migration results if the entire sample was submerged.
This device provides an accurate measurement of the substances that would actually transfer to the food during use.
Apparatus Design
The cell consists of two heavy metal or glass plates that clamp the polymer sample between them, forming a leak-proof seal. The food simulant is poured into a chamber on one side of the film, which exposes only that surface to the liquid. This design prevents edge-leaking and ensures test accuracy.
Testing Advantages
Traditional total-immersion testing exposes both sides of the polymer and its cut edges, which often yields artificially high migration levels. By limiting exposure to the contact surface, the migration cell provides a realistic simulation of actual packaging conditions. This is essential for validating the safety of complex laminates.
Process Application
These cells are used by quality control laboratories to verify that new coextruded films meet specific migration limits. The testing results are included in the compliance documentation for the film. This helps secure regulatory approval for the packaging.
