Nonlinear viscoelastic diffusion in concentrated polystyrene/ethylbenzene solutions

✍ Scribed by S. J. Huang; C. J. Durning

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 360 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19970930)35:13<2103::aid-polb11>3.0.co;2-8

✦ Synopsis

Nonlinear gradient-driven diffusion was studied in concentrated polystyrene (PS)/ethylbenzene (EB) solutions using vapor sorptions with a finite driving force. The nonlinear sorptions were carried out on thin films ( à2.05, 3.50 mm thick) at conditions where non-Fickian, ''viscoelastic'' effects appear. These data were modeled with the nonlinear diffusion equation studied by Tang. Four dimensionless material parameters in the model were determined from a limited amount of linear-response, differential sorption data on PS/EB mixtures measured in the same range of experimental conditions as for the nonlinear sorptions. The nonlinear model successfully predicts the observed nonlinear response either above or below the glass transition ( T g ). In order to simultaneously capture the nonlinear response both above and below T g , the abrupt change in the concentration dependence of physical properties at T g must be accounted for.