Heat capacities and related thermal data for diethyl phthalate crystal, glass, and liquid to 360 K

Experimentally determined heat capacity valu es, precise to within 0.1 percent, and related thermal data are reported for quenched and annealed diethyl phthalate glasses from ]0 oK to the glass transformation te mperature, Tg (around 180 O K) , for the liquid from T" to 360 oK, and for the crystal from 10 oK to the melting temperature (269.9 O K). The mole fraction of liquidsoluble, solidinsoluble impurity in the sample as determined by fractional melting was 0.0012. Co mmon thermodynamic properties calc ulable from the experimental data are reported. The heat capacities of the two glasses differ by more than the uncertainty of the meas urements, and both lie below that of the crystal in the range from 30 to 75 oK. At low temperatures, just above 10 oK, the heat capacities of the glasses rise as much as 8 percent above that of the crystal.