Europhys. Lett.
Volume 68, Number 1, October 2004
Page(s) 58 - 64
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 September 2004
Europhys. Lett., 68 (1), pp. 58-64 (2004)
DOI: 10.1209/epl/i2004-10214-6

Scaling out the density dependence of the $\alpha$ relaxation in glass-forming polymers

C. Alba-Simionesco1, A. Cailliaux1, A. Alegría2 and G. Tarjus3

1  Laboratoire de Chimie Physique, Bâtiment 349 Université de Paris Sud, F-91405 Orsay, France
2  Departamento de Física de Materiales (UPV/EHU) and Unidad de Física de Materiales (CSIC-UPV/EHU) Apartado 1072, E-20080 San Sebastián, Spain
3  Laboratoire de Physique Théorique des Liquides Université Pierre et Marie Curie 4 Place Jussieu, F-75252 Paris Cedex 05, France

received 15 March 2004; accepted in final form 6 August 2004

We show that the density and temperature dependences of the $\alpha$-relaxation time of several glass-forming polymers can be described through a single scaling variable $X=e(\rho)/T$, where $e(\rho)$ is well fitted by a power law $\rho^x$, x being a species-specific parameter. This implies that "fragility" is an intrinsic, density-independent property of a glass-former characterizing its super-Arrhenius slowing-down of relaxations, and it leads us to propose a modification of the celebrated Angell plot.

64.70.Pf - Glass transitions.
61.20.Lc - Time-dependent properties; relaxation.
61.41.+e - Polymers, elastomers, and plastics.

© EDP Sciences 2004