Nature of the Rotational Phase Transition in Paraffin Crystals

Abstract

An attempt has been made to calculate the change in lattice energy accompanying the rotational phase transition cocurring in the paraffins. The calculation is based on the assumption that the change in the lattice energy corresponding to the discontinuous change in the crystal structure may be approximated by the difference in the theoretical lattice potential energies of the crystal before and after the transition has occurred. A specific model for the rotation mechanism has been postulated, and a method devised for calculating the average repulsive energy of a system of cooperatively rotating rigid chains. The results of the calculation indicate that the change in lattice energy is of the same order as the experimental heat of transition.