Abstract: | In a search for a liquid-liquid transition in the melt of polystyrene, we have measured and analyzed a number of compression isotherms to 1800 kg/cm2 in a relevant temperature range (1.2Tg < T < 1.4Tg). Volume data were recorded at pressure intervals of 10 kg/cm2, i.e., at pressure intervals 5-20 times smaller than used in previous work. For the analysis the data were fitted to the Tait equation. Deviations between fits and data are small, typically 0.0004 cm3/g, but nonrandom. From the absence of any systematic shifts of the nonrandom deviation patterns with temperature, we conclude that the deviations are not manifestations of a pressure-dependent liquid-liquid transition, and that there is, in fact, no evidence for the existence of such a transition in our data. |