Dielectric studies of glass transition in confined propylene glycol

 
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Dielectric studies of glass transition in confined propylene glycol (EN)

Kyritsis, A (EN)
Daoukaki, D (EN)
Barut, G (EN)
Pissis, P (EN)
Pelster, R (EN)
Nimtz, G (EN)

N/A (EN)

The dynamical behaviour of the glass transition of propylene glycol confined in droplets in butyl rubber (three-dimensional confinement, mean droplet diameter d = 8-11 nm) and in pores in controlled porous glasses (two-dimensional confinement, mean pore diameter d = 2.5-7.5 nm) has been studied in detail by means of broadband dielectric spectroscopy (5 Hz-2 GHz) and of thermally stimulated depolarization current measurements. Effective medium theory corrections of the data are discussed. The results indicate the existence of a relatively immobile interfacial layer close to the wall. For the volume liquid the dynamics of the glass transition becomes faster and the glass transition temperature T-g decreases compared to the bulk liquid. The shifts Delta T-g increase with decreasing d, are larger in butyl rubber than in controlled porous glasses (three-dimensional versus two-dimensional confinement) and vanish for d approximate to 10-12 nm. These results are discussed in relation to those obtained with polymers confined in thin polymeric films (one-dimensional confinement) and in semicrystalline polymeric samples and are explained on the basis of the cooperativity concept and the model of Adam and Gibbs. The cooperativity length xi at T-g is determined to be xi less than or equal to 5-6 nm in both butyl rubber and controlled porous glasses. Interesting effects of confinement are observed on the shape of the dielectric response of the process associated with the glass transition. (EN)

journalArticle

FORMING LIQUIDS (EN)
POROUS-GLASS (EN)
ALPHA-RELAXATION (EN)
TEMPERATURE (EN)
MOLECULAR LIQUIDS (EN)
METHACRYLATE) (EN)
SIZE (EN)
DYNAMICS (EN)
COOPERATIVITY (EN)
POLYMER-FILMS (EN)

Εθνικό Μετσόβιο Πολυτεχνείο (EL)
National Technical University of Athens (EN)

Journal of Physics Condensed Matter (EN)

1998


IOP PUBLISHING LTD (EN)



*Η εύρυθμη και αδιάλειπτη λειτουργία των διαδικτυακών διευθύνσεων των συλλογών (ψηφιακό αρχείο, καρτέλα τεκμηρίου στο αποθετήριο) είναι αποκλειστική ευθύνη των αντίστοιχων Φορέων περιεχομένου.