For the quality assurance of materials and articles intended for the contact with food the knowledge of the mass transfer phenomena at the interface of the different media is of eminent importance. As these interface phenomena – in both directions – occur in accordance with known physical laws a reliable theoretical estimation of the mass transfer is possible in many cases, if the necessary specific values of the migrants and media properties are known. The mass transfer at the interface between two media is determined by two independent processes: a kinetic one, the real mass transfer, and a thermodynamic one, the partition of the transferred substance between the media. For the last there is still a lack of basic knowledge. Therefore one emphasis of the project is put on the experimental determination of partition coefficients at different temperatures, especially the partition of a substance between two different packaging layers.
Aim of this project is the development of an estimation model for partition coefficients which can be used together with the diffusion coefficients for the estimation of mass transfer at multilayer structures.
In the first year of the project a method for the experimental determination of partition coefficients between different polymers has been developed. Low density polyethylene (LDPE) films are used as a reference matrix. A model for partition coefficient estimation has also been developed which is based on specific structure increments of the migrants, and its validation are planned for 2005.