Detection of molecular associations in liquids by photopyroelectric measurements of thermal effusivity

Abstract

A front photopyroelectric (PPE) configuration, with an opaque sensor and a thermally thick sensor and sample, was used to measure the thermal effusivity of some liquid mixtures. The information (the value of the thermal effusivity) is contained in the phase of the signal, leading to accurate and reproducible results. The thermal effusivity proved to be a sensitive parameter, able to detect molecular associations in binary liquid mixtures. Applications on associative (water–ethanol) and non-associative (water–ethylene glycol) liquid mixtures are presented.