SIMULATION OF THE GLASS-TRANSITION IN POLYMERIC SYSTEMS - EVIDENCE FOR AN UNDERLYING PHASE-TRANSITION

The bond fluctuation model of polymer chains on sc lattices with an en ergy that favours long bonds can describe the slowing down of supercoo led melts that approach the glass transition in qualitative similarity with various experiments. In this paper we focus on the question of w hether there exists a correlation length that increases to large value s when the temperature is lowered towards the glass transition. Two ty pes of analysis are presented: firstly density oscillations near hard walls become long range, and the resulting correlation length becomes larger than the gyration radius, secondly oscillations in the pair cor relation function in real space also become long range, and a similar correlation length can hence also be deduced in the bulk, without reco urse to surface effects. In contrast, a finite-size scaling analysis o f the diffusion behaviour of chains in small three-dimensional lattice s with periodic boundary conditions does not give evidence for this le ngth, unlike earlier results for the two-dimensional case.