Empirical Determination of the Thermodynamic Equilibrium Fluctuation of Volume, Pressure, Entropy, and Temperature for Polyethylene Based on the Pressure‐Volume‐Temperature‐Entropy Equation of State

ABSTRACT Fluctuations in thermodynamic equilibrium states are a useful tool to investigate a dynamic molecular motion in a small system inside a large homogeneous system. The thermodynamic equilibrium fluctuations of the volume, V , pressure, P , entropy, S , and temperature, T , in the small system for polyethylene ( PE ) were determined empirically based on an empirical P ‐ V ‐ T ‐ S equation of state and theories by Landau and Lifshitz and by Kubo where it was found there was two types of the fluctuation probability density and a simple relationship between a square average of fluctuation for P , V , T and S .