Glass transition in chlorobenzene–decalin under pressure

Abstract

We have investigated the dielectric properties of a 17.2 mol % mixture of chlorobenzene and decalin in the supercooled and in the glassy state under hydrostatic pressure up to 400 MPa. The dielectric loss shows the well-known primary (α) relaxation and a secondary (β) relaxation the origin of which is still being debated. The glass transition temperature Tg increases linearly with pressure. The fragility is pressure independent. With increasing pressure the relaxation strength of the β process rises at the expense of the α process. Above around 160 K, where devitrification occurs at atmospheric pressure, the activation energy of the secondary relaxation process is roughly twice that at lower temperatures. Both energies are proportional to Tg, indicating a strong correlation between α and β processes. A possible origin of the secondary relaxation is rationalized by critical clusters in the melt.

Two-order-parameter model of the liquid–glass transition. I. Relation between glass transition and crystallization

“…(b) Mixing of different-size particles prevents crystallization for simulations using Lennard-Jones particles [118]. (c) There are a number of examples of a glass-forming mixture, both of whose component molecules themselves are very poor glass formers [119].…”

Isochronal temperature–pressure superpositioning of the α-relaxation in type-A glass formers

“…The implication is that such local motion, not involving the entire molecule, may not be a JohariGoldstein process. Contrarily, s b for sorbitol [18] and for chlorobenzene/decalin mixtures [19], both increase with pressure, and are clearly JohariGoldstein processes.…”

The Role of Density and Temperature in the Dynamics of Polymer Blends

“…Our principal interest concerns the influence that volume and temperature have on segmental relaxation in the blends, in comparison to the neat components. Current models of blend dynamics restrict their consideration to the variation of τ R with T, and only a few experimental studies have addressed the effect of pressure on τ R for mixtures, 28,35,36 block copolymers, 37 or blends. [38][39][40][41] Fundamental understanding, however, requires analysis of what governs the observed dependences.…”