The effect of thermodynamic variables on polymer chain dynamics

The dynamics of polymer chains are examined in terms of their relationship to the local segmental relaxation process. Although the differing responses to changes in temperature and pressure cause breakdown of time-temperature and time-pressure superpositioning near the glass transition, a recently discovered scaling law can be applied to both relaxation modes. This scaling yields master curves of the global chain relaxation times and the local segmental relaxation times, which can be used to determine the dynamics at high pressure from ambient pressure measurements. The scaling relation also provides a measure of the steepness on the intermolecular potential in the vicinity of the distance of closest approach between segments.