Polyolefin Non Intentionally Added Substances Identification Basics
Polyolefin non-intentionally added substances require chromatographic screening, Cramer toxicological tiering, and finished article migration verification.
Functional Barrier 10 Ppb
Meaning
Protective layers within a multi-component plastic structure prevent the migration of non-authorized substances into the contents of a package. The functional barrier 10 ppb standard refers to the specific migration limit where the concentration of a chemical must remain below ten parts per billion. This threshold is widely used to manage the safety risks associated with recycled materials or non-listed additives in food contact applications.
Migration Control
Layers of virgin resin or high barrier polymers act as a shield between the core material and the contact surface. When a functional barrier 10 ppb is established, it ensures that even if the middle layer contains impurities from a recycling stream, those molecules cannot diffuse through the barrier at a rate that would reach the inner surface. The effectiveness of this shield depends on the polymer type, the thickness of the barrier layer and the storage temperature of the final product.
Analytical Threshold
Measurement at such low concentrations requires high resolution gas chromatography or mass spectrometry. Reaching the functional barrier 10 ppb level means that the migration is effectively negligible for most non-toxic substances. This numerical value acts as the cut off point for safety assessments when a processor uses regrind or experimental additives that lack a formal specific migration limit in the primary regulations.
Material Selection
High density polymers with low permeability provide the most reliable performance for thin wall applications. While a functional barrier 10 ppb can be achieved with various resins, the use of polyamides or ethylene vinyl alcohol often allows for a thinner barrier layer compared to standard polyolefins. Designers must account for the potential thinning of these layers during thermoforming or blow moulding to ensure the barrier remains intact across the entire part geometry.
Variations in processing temperature also influence the diffusion coefficient of the polymer, meaning that a barrier that works at room temperature might fail if the part is subjected to hot fill conditions or microwave heating. Engineers must therefore validate the barrier integrity under the most extreme conditions the part is expected to endure.