Influence of temperature and pressure on the dynamics of glass formers explored by dielectric spectroscopy

Author

Casalini, R. ; Capaccioli, S. ; Presto, S. ; Lucchesi, M. ; Rolla, P.A. ; Corezzi, S. ; Paluch, M.

Author_Institution

Dipartimento di Fisica, Pisa Univ., Italy

Volume

8

Issue

3

fYear

2001

fDate

6/1/2001 12:00:00 AM

Firstpage

395

Lastpage

400

Abstract

The dynamics of the epoxy compound polyphenyl-glycidyl-ether-coformaldehyde was investigated by wideband dielectric spectroscopy (10^-2 to 10¹⁰ Hz) by varying either pressure or temperature. The measurements were undertaken in two different conditions: under isobaric condition (atmospheric pressure) varying temperature down to the supercooled and glassy phases and under isothermal conditions by changing the pressure from 0.1 to 270 MPa. The analysis of the structural relaxation time behavior either varying the temperature or the pressure was found to agree well with a previously derived expression for τ(T, P) based on a cooperative model. In particular it was found that with a unique set of parameters it is possible to describe the 2-dimensional surface τ(T, P) over a wide range of temperature and pressure. This result agrees well with the observed independence of the fragility in both isothermal and isobaric conditions

Keywords

dielectric losses; glass transition; polymer blends; polymer structure; 0.1 to 270 MPa; 1E-2 to 1E10 Hz; 2-dimensional surface; cooperative model; epoxy compound; glass formers; isobaric condition; isothermal condition; polyphenyl-glycidyl-ether-coformaldehyde; structural relaxation time; wideband dielectric spectroscopy; Atmospheric measurements; Dielectric measurements; Electrochemical impedance spectroscopy; Glass; Isobaric; Isothermal processes; Phase measurement; Pressure measurement; Temperature; Wideband;

fLanguage

English

Journal_Title

Dielectrics and Electrical Insulation, IEEE Transactions on

Publisher

ieee

ISSN

1070-9878

Type

jour

DOI

10.1109/94.933352

Filename

933352