Meaning
Laboratory extraction procedures designed to isolate unreacted monomers, low molecular weight oligomers, processing aids, and additives measure potential chemical migration from polyethylene and polypropylene materials. Performing polyolefin extractables screening provides data on non-bonded species capable of diffusing out of a polymer matrix into contact media. The methodology applies to film grades, blow moulding compounds, sheet extrusion stock, and injection moulding resins destined for medical or food applications.
Solvent Extraction
Testing protocols involve incubating polymer pellets, ground flake, or finished moulded parts in organic solvents under controlled duration and elevation of temperature. Reflux extraction with hexane or isooctane swells the polyolefin matrix, accelerating the release of internal compounds. Executing polyolefin extractables screening under aggressive solvent conditions simulates worst-case long-term storage scenarios.
Instrumental Quantification
Solvent extracts undergo concentrated evaporation before analysis through gas chromatography and liquid chromatography paired with selective detectors. High-resolution mass spectrometers quantify antioxidant degradation products, slip agents, plasticizers, and residual catalyst residues. Data from polyolefin extractables screening generate compound inventories that safety assessors compare against regulatory threshold values and specific migration limits.
Chromatographic peaks are assigned structural identities by matching retention indices and mass spectra against spectral reference libraries. Quantification relies on response factors established from certified reference standards analyzed under identical analytical parameters.
Resin Specification
Converter purchasing contracts set maximum allowable total extractable limits to ensure consistent processing performance and regulatory compliance. Polyolefin extractables screening identifies resin lots with elevated oligomer contents that cause die lip buildup during film extrusion or mould plate-out during injection moulding.
