Measuring the dynamic thermal expansivity of molecular liquids near the glass transition

TL;DR

This paper introduces a capacitative method to measure the dynamic thermal expansivity of molecular liquids near the glass transition, extending previous techniques to include time-domain experiments and small temperature steps.

Contribution

It presents a novel measurement approach for molecular liquids, accounting for volume contraction during cooling, and extends the dynamical range of previous methods.

Findings

Successful measurement of thermal expansivity in ultraviscous regime

Extended dynamical range through time-domain experiments

Accounted for liquid contraction during cooling

Abstract

Based on previous works on polymers by Bauer et al. [Phys, Rev. B (2000)], this paper describes a capacitative method for measuring the dynamical expansion coefficient of a viscous liquid. Data are presented for the glass-forming liquid tetramethyl tetraphenyl trisiloxane (DC704) in the ultraviscous regime. Compared to the method of Bauer et al. the dynamical range has been extended by making time-domain experiments and by making very small and fast temperature steps. The modelling of the experiment presented in this paper includes the situation where the capacitor is not full because the liquid contracts when cooling from room temperature down to around the glass-transition temperature, which is relevant when measuring on a molecular liquid rather than polymer.