Intrinsic Behavior of the Internal Energy, Enthalpy, Helmholtz Free Energy and Gibbs Free Energy for the Polyethylene in the Process When Two of Thermodynamic Factors, Pressure, Volume, Temperature and Entropy are Constant

The thermodynamic behaviors occur in either the process with one thermodynamic factor in the P , V , T , and S being constant or that with two thermodynamic factors being constant. The thermodynamic changes of P , V , T , and S in a specific process when two of the thermodynamic factors are constant were determined for polyethylene (PE) based on the intrinsic equation of state for various ensembles determined by the empirical P ‐ V ‐ T ‐ S equation of state. The intrinsic thermodynamic behaviors of the internal energy, U , enthalpy, H , Helmholtz free energy, A , and Gibbs free energy, G , for PE in various specific processes when two thermodynamic factors, P , V , T and S , are constant were determined quantitatively based on the thermodynamic changes of P , V , T , and S in the specific process.