Migration Testing Conditions That Do Not Match Your Filling Line
Matching migration simulant and thermal parameters to exact filling line mechanics prevents compliance invalidation during customs and market audit checks.
Fickian Diffusion Kinetics
Mass Transfer
Mathematical formulas predict how quickly volatile substances move through polymeric packaging materials over time. Using fickian diffusion kinetics helps packaging engineers calculate the rate at which chemical migrants travel from a board substrate into food. The rate of mass transport is driven by the concentration gradient.
Migration Mathematical Model
Calculation of substance movement relies on diffusion coefficients that depend strongly on temperature and polymer density. Under fickian diffusion kinetics, the flux of a migrant is proportional to the concentration gradient, which allows predictable modeling of low-molecular-weight compounds over storage periods. This relation allows the simulation of long-term migration using short-term high-temperature tests.
Food safety authorities accept these mathematical models when direct testing is difficult to execute, provided that the physical properties of the polymer are fully characterized. The calculation assumes a homogeneous barrier layer where the temperature remains constant.
Packaging Boundary
Barrier efficiency depends on the thickness and polymer morphology of the co-extruded layers. When a functional barrier operates within the regime of fickian diffusion kinetics, the time required for a migrant to break through increases with the square of the barrier thickness. This non-linear relationship dictates the minimum layer thickness required for safe packaging.
It establishes the limits of paperboard packaging designs that incorporate recycled fibres.