From the MD simulations, T g can be determined by monitoring the polymer electrolyte densities as a function of temperature. This transition from a soft/rubbery polymer state in the high-temperature range to a glassy/rigid state in the low-temperature range manifests as a slope change in the simulated density and temperature. The point of intersection between the fitted straight lines corresponding to the low-temperature (40-140) and high-temperature (300-440) ranges can be considered as the T g of the simulated systems.