1. Modeling substance contamination of plastic materials

1.1 Molecular transport mechanisms

Thermoplastics, improperly called "plastics" or "plastic materials", are made up of long intertwined chains of polymers (molecular weight greater than 50,000 g · mol ^-1 ) and formulated with various additives (plasticizers, colorants, stabilizers, etc.) to meet the material's technical specifications. The interlacing of macromolecules is associated with a slow relaxation process at room temperature, responsible for the high cohesive energy of plastics. Polymer chains can locally adopt a crystalline morphology (semi-crystalline polymers) and/or a preferred orientation (oriented polymers). The amorphous phase exhibits two distinct mechanical behaviors, on either side of the glass transition temperature,...