PHYSICAL ASPECTS OF POLYMER STABILIZATION

The transport properties of various additives were studied by measurin g their diffusion rate and solubility in low density polyethylene (LDP E), a blend of low density and linear low density polyethylene (LDPE/L LDPE), and ethylene vinyl acetate copolymer (EVA) at different tempera tures. A correlation was found between the diffusion rate and the frac tional free-volume of the noncrystalline phase of the polymer, as well as the specific volume of the diffusant. Deviations from the theoreti cal expectations were attributed to the different free energies of var ious physical states of additives.