Recycled Plastic Food Contact Compliance and Non Intentionally Added Substance Testing Methods
Recycled plastic food contact compliance requires rigorous surrogate challenge testing, non-target NIAS screening, and lot-traced migration verification.
Oligomers
Meaning
Low molecular weight polymers consisting of a small number of repeating structural units exhibit distinct physical behaviors compared to high molecular weight resins. In plastic processing, oligomers represent these short-chain molecules that remain unconverted during polymerization or form through thermal degradation during extrusion. These mobile species can migrate to the surface of molded parts, causing cosmetic and functional issues.
Resin suppliers must control their concentration during the initial polymerization process.
Material Migration
Thermal energy during injection moulding mobilizes the short-chain molecules within the polymer matrix. Such oligomers migrate to the melt flow front and deposit onto the cooler surfaces of the mould cavity. Extruders and molders refer to this residue as plate-out, which degrades surface gloss.
Moulding Defect
Accumulated mold deposits block the venting channels, leading to trapped air and burn marks on the molded components.
Sourcing Specification
Processors must analyze raw material datasheets and specify resin grades with low extractable content for sensitive applications. In medical and food contact products, high concentrations of oligomers raise the risk of chemical leaching, which violates regulatory standards. Recycled resins and regrind material often contain higher fractions of these low-weight chains due to cumulative thermal degradation from previous heat histories.
Sourcing departments should establish maximum limits for these species when buying materials for high-purity applications.