Structural aspects of the glass transition in three-dimensional polymer melts

Abstract

We discuss structural aspects of three-dimensional polymer melts undergoing glass transition. Our Monte Carlo study is based on the well known bond-fluctuation model including van der Waals interaction and bond-length potential. Results are presented for different cooling rates and a wide range of temperatures. The glass-transition temperature, T _g , was determined by the significant change in various static and dynamic quantities, such as the static structure factor of individual polymer chains and the incoherent scattering function. Below T _g , the latter is characterized by division into a Debye-like short-time regime and two separate time regimes with stretched-exponential behaviour. Further investigation by means of block density distribution analysis revealed an inhomogeneous, non-Gaussian distribution of mass below T _g . A direct proof for the existence of cavities and clusters of effective monomers has been given by visualization via a two-dimensional projection technique.