The high temperature transition of polyethylene into a Condis phase,described on the basis of the cluster-entropy hypothesis (CEH)

On the basis of atomistic calculations a rotator model of the high temperature Condis phase of polyethylene is proposed. Its cooperative statistical treatment (using CEH for the lateral packing of chains) explains the first order transition from the all-trans crystal as well as the transition dataT _t ,S _t ,V _t . We found that the normal melting (i. e. at pressures below the triple point) is also governed by the onset of the Condis phase.This abbreviation was introduced by B. Wunderlich 1], to describe conformationally disordered oligomer or polymer crystals.Dedicated to Professor Dr. R. Kosfeld on the occasion of his 60th birthday.