Meaning
Laboratory testing protocol designed to quantify the diffusion of volatile additives, unreacted monomers, plasticizers, and antioxidants from a plastic matrix into contact fluids or food simulants. Material characterization involves submerging test specimens in specific solvents under elevated temperatures to accelerate chemical transport. Conducting polymer migration testing ensures that plastic packaging materials comply with health and safety limits for food contact and medical packaging applications.
The testing protocol stops applying to non-porous materials like glass or metals that do not contain mobile organic additives.
Analytical Methods
Gas chromatography and mass spectrometry identify extractable organic compounds extracted during simulant immersion. Liquid chromatography measures non-volatile additives like light stabilizers and slip agents that leach into liquid test media. Quantification requires calibration curves using pure reference standards to measure microgram concentrations accurately.
Diffusive Mechanism
Temperature, contact duration, material thickness, and polymer crystallinity govern the rate at which internal molecules diffuse to the surface. Amorphous resins with low glass transition temperatures exhibit faster additive mobility than highly crystalline plastics. Thermal history during injection moulding alters polymer density, directly affecting diffusion rates.
Compliance Standard
Regulatory bodies enforce strict specific migration limits for individual chemical substances to protect consumer safety. Exceeding migration limits requires reformulating the resin blend, reducing additive loadings, or applying physical barrier coatings. Certified test results provide legal proof of regulatory compliance before commercial product release.
