Heat Capacities of Polyethylene from 2 to 360 K. II. Two High Density Linear Polyethylene Samples and Thermodynamic Properties of Crystalline Linear Polyethylene.

Heat capacities of two high density linear polyethylene samples were measured from 2 to 360 K. By incorporating the results from the previous work of this series, thermodynamic properties of completely crystalline linear polyethylene may be estimated. C p , H - H0, S and - (G - H0) at 298.15 K for crystalline linear polyethylene are estimated to be 22.60 J K-1 mol-1, 3544 J mol-1, 23.02 J K-1 mol-1 and 3319 J mol-1, respectively. Spontaneous adiabatic temperature drifts were observed in both samples near 240 K. These drifts may be attributed to the enthalpy relaxation phenomena occurring in the glass transformation region.