STRUCTURAL TRANSFORMATIONS IN CRYSTALLINE POLYETHYLENE - ROLE OF TOPOLOGICAL SOLITONS IN PREMELTING

Dynamics of a thermalized chain of crystalline PE is simulated in the approximation of immobile neighbor chains. Formation of local topologi cal defects with increasing temperature is studied by Brownian dynamic s. It is shown that thermal vibrations of a chain result in the format ion of defects of a single type (topological solitons) corresponding t o extension (contraction) of a chain zigzag by halfperiod with simulta neous twist by 180 degrees. The defects appear in the form of pairs of topological solitons of opposite signs. They move along the chain as free Brownian particles. The concentration of defects sharply increase s in the vicinity of the melting point of a crystal.