Proceedings of the X. International Macromolecular Colloquium pages:1-2
X. International Macromolecular Colloquium edition:X location:Gramado, Brasil date:10-13 April 2005
Monitoring the coil-stretch transition of polymers in transient extensional flow provides a unique possibility to observe the stress distribution between polymer and solvent even for sub-ppm concentrations. In this paper we will present investigations on the capillary break-up behavior of polystyrene solutions with narrowly-distributed molecular weight that are progressively diluted. We show that there exists a critical concentration below which the dominant stress resisting breakup is carried solely by the solvent. This observation is supported by numerical simulation of the stress evolution based on the one-dimensional analysis of Entov and Hinch for transient extensional flows. The influence of molar mass and molar mass distribution on the stress evolution and the critical dilution concentration is also discussed.