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 - H ₀ , S and - (G - H ₀ ) 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.