STRUCTURAL ASPECTS OF THE GLASS-TRANSITION IN 3-DIMENSIONAL POLYMER MELTS

We discuss structural aspects of three-dimensional polymer melts under going glass transition. Our Monte Carlo study is based on the well kno wn bond-fluctuation model including van der Waals interaction and bond -length potential. Results are presented for different cooling rates a nd a wide range of temperatures. The glass-transition temperature, T-g , was determined by the significant change in various static and dynam ic quantities, such as the static structure factor of individual polym er chains and the incoherent scattering function. Below T-g, the latte r is characterized by division into a Debye-like short-time regime and two separate time regimes with stretched-exponential behaviour. Furth er investigation by means of block density distribution analysis revea led an inhomogeneous, non-Gaussian distribution of mass below T-g. A d irect proof for the existence of cavities and clusters of effective mo nomers has been given by visualization via a two-dimensional projectio n technique.