Meaning
A semi-empirical coefficient represents the resistance of a specific polymer to the diffusion of chemical substances. In migration modeling, the piringer model parameter is used to estimate the diffusion coefficient of additives or contaminants when experimental data are unavailable.
Theoretical Basis
This calculation relies on an upper-limit estimation of diffusion based on the molecular weight of the migrant and the temperature. In the determination of the piringer model parameter, polymers are classified by their density and glass transition temperature to assign a value that ensures a conservative calculation of migration. This approach is designed to err on the side of safety for regulatory compliance.
Industrial Application
Processors use this parameter to perform migration simulations for regulatory dossiers without conducting laboratory tests. By applying the piringer model parameter, packaging designers can demonstrate that a new polymer formulation will not exceed migration limits during the shelf life of the product. This simulation simplifies the design process and reduces the time required to bring new products to the market.
Model Constraint
The parameter is designed to generate overestimates of migration and can be too conservative for high-barrier polymers. For these materials, using the piringer model parameter can result in a prediction that is many times higher than the actual migration rate.
