Influence of solvent absorption on the migration of Irganox 1076 from LDPE

The effect of solvent absorption on additive migration was studied by relating the diffusion coefficient (D) of Irganox 1076 to the maximum solvent absorption of different solvents in low-density polyethylene (LDPE) film. Solvents tested were ethanol, isopropanol, isooctane, ethylacetate, cyclohexane, tributyrin, tricaprylin and olive oil. Diffusion and partition coefficients were determined by fitting the migration curves, i.e. the concentration of Irganox 1076 in solvent as a function of time, with Fick's diffusion equation. The results for the low molecular weight solvents show that with increasing maximum solvent absorption, D of Irganox 1076 is increasing as well. This trend is not observed for the two triglycerides and olive oil. In spite of absorption, no increase in D was observed. The obtained result is the basis of an extended predictive migration model that, besides migrant and polymer properties, is also based on the maximum solvent absorption in the polymer.