SynopsisThe solubilities of six phenolic antioxidants in poiypropylene and polyethylene were measured between 5OoC and 100OC. Measurements were also made of their solubilities in a range of liquid alkanes. The measured solubilities at 7OoC were consistent with regular solution theory and could be used to predict values to within one half of an order of magnitude. No simple correlation wm found when regular solution theory was applied to predict the dependence of solubility on either temperature or the molar volume of the solvent. Hence, contrary to previous reports, the relative solubilities of antioxidants, measured at high temperatures or in alkane solvents, cannot be used to estimate their relative solubilities in polymers at room temperature.