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 energy that favours long bonds can describe the slowing down of supercooled melts that approach the glass transition in qualitative similarity with various experiments. In this paper we focus on the question of whether there exists a correlation length that increases to large values when the temperature is lowered towards the glass transition. Two types 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 correlation function in real space also become long range, and a similar correlation length can hence also be deduced in the bulk, without recourse to surface effects. In contrast, a finite-size scaling analysis of the diffusion behaviour of chains in small three-dimensional lattices with periodic boundary conditions does not give evidence for this length, unlike earlier results for the two-dimensional case.