Meaning
Total mass loss from a polymer sample during solvent immersion measures the amount of low molecular weight compounds released into an extraction medium. Polyolefin extract consists of waxes, processing aids, or short chain oligomers that leach out when the material contacts a liquid carrier. Regulatory bodies set limits on these mobile components to ensure chemical safety in food contact applications.
Moulding Constraints
High levels of these mobile species alter the surface energy of finished parts during injection production. Resin suppliers define the fraction of extractables to control part adhesion and painting performance. Excess migration leads to plate out on tooling surfaces which creates costly maintenance cycles or finish defects.
Economic Variables
Virgin resin batches demonstrate consistent low extraction values that align with strict batch specifications. Regrind material frequently exhibits higher concentrations of mobile additives due to thermal degradation during previous processing runs. Cost management involves calculating the acceptable limit for regrind addition while remaining within the threshold for physical part integrity.
Validation Method
Gravimetric analysis determines the weight change after exposing a film or moulded plaque to a specific solvent for a fixed duration. Technicians perform this measurement by drying the residue after evaporating the extraction fluid to calculate the percentage of total mass lost. Precise oven temperatures and solvent purity represent the two factors governing result consistency across various testing laboratories.
