Dielectric relaxation at the glass transition of confined N-methyl-ε-caprolactam

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1998 (EN)
Dielectric relaxation at the glass transition of confined N-methyl-ε-caprolactam (EN)

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

N/A (EN)

The effects of confinement on the glass transition of the nonassociating glass-forming liquid N-methyl-ε-caprolactam were studied in detail by means of broadband dielectric relaxation spectroscopy, 5 Hz-2 GHz, and thermally stimulated depolarization current measurements, 77-300 K. The liquid was two dimensionally confined in the pores of controlled porous glasses with mean pore diameter d = 2.5, 5.0, 7.5, and 20.0 nm (Gelsil glasses) and d = 4.0 nm (Vycor glass) and three dimensionally confined in butyl rubber with mean droplet diameter d=7.6 nm. The confined liquid is classified into two fractions: a relatively immobile interfacial layer close to the wall and the inner layer (volume liquid). For the volume liquid the a relaxation associated with the glass transition becomes faster and the glass transition temperature decreases compared to the bulk liquid. These effects increase with decreasing d and are stronger for three- than for two-dimensional confinement. They can be understood on the basis of the cooperativity concept and the configurational entropy model of Adam and Gibbs. The systematic variation of d allows the determination of the cooperativity length ξ at Tg to ξ≤s10-12 nm. (EN)


Glass Transition (EN)
Dielectric Relaxation (EN)

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

Physical Review B - Condensed Matter and Materials Physics (EN)


N/A (EN)

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