Meaning
Computational simulation of the movement of atoms, molecules, or ions through a polymer matrix over time. In packaging design, mass transport modeling calculates the migration of additives, monomers, or external gases through plastic films to predict shelf life and compliance. This technique reduces the need for expensive and lengthy physical migration tests.
The equations are based on fundamental laws of diffusion and solubility.
Mathematical Foundation
Diffusion equations derived from Fick’s laws form the core of the calculation process. When performing mass transport modeling, the simulation requires input parameters such as the diffusion coefficient and the partition coefficient of the permeant in the polymer. These values vary with temperature and the crystallinity of the resin.
The mathematical solver then calculates concentration profiles across the thickness of the barrier.
Process Simulation
Industrial engineers utilize these digital simulations to optimize the structure of coextruded films without pouring raw material. Through mass transport modeling, developers can evaluate different resin combinations and layer thicknesses in a virtual environment. This trial shows how changing a nylon layer to an ethylene vinyl alcohol layer affects the overall gas transmission rate.
The simulation helps in selecting the most cost-effective resin configuration for a specific shelf-life target, reducing trial-and-error runs on the extrusion line. It also allows developers to simulate the impact of using recycled materials by calculating the diffusion of potential contaminants through the multi-layer film.
Diffusion Prediction
Long-term stability assessments rely on these simulated outcomes to ensure packaging safety under various climatic zones. Accurate mass transport modeling predicts how a package will perform when stored in hot and humid conditions compared to cold storage. This analysis is especially important for pharmaceutical blister packs where moisture ingress can degrade the active ingredient.
The resulting predictions guide the selection of protective secondary packaging.
