Meaning
Mobile substances within a plastic matrix can move to the surface of a part or leach into the surrounding environment. In food packaging and medical devices, polymeric migrants are closely monitored to ensure that additives like plasticizers or antioxidants do not contaminate the contents. These substances are usually low molecular weight compounds that are not chemically bonded to the polymer chains.
Chemical Mobility
Diffusion rates through the plastic are influenced by the temperature and the density of the resin. When a part is exposed to heat or fatty liquids, the speed at which polymeric migrants reach the surface increases. This movement can change the physical properties of the part, such as its flexibility or color.
Leaching Risk
Regulatory agencies set strict limits on the amount of material that can transfer from a container to its contents. Testing for polymeric migrants involves placing the part in a stimulant liquid for a specific period and then analyzing the liquid with chromatography. This process identifies both the identity and the concentration of the transferred chemicals.
Verification of compliance is required for any material used in medical applications or infant products.
Substance Transfer
Contamination of the environment or the product is the primary concern for manufacturers of consumer goods. High levels of polymeric migrants can lead to taste issues in drinking water or the failure of biocompatibility tests in surgical tools.
