Impedance analysis of the barrier effect of coil-coated materials: Water uptake and glass transition variations - Archive ouverte HAL Access content directly
Journal Articles Progress in Organic Coatings Year : 2021

Impedance analysis of the barrier effect of coil-coated materials: Water uptake and glass transition variations

Abstract

In the present work, an industrial polyester coil-coated steel sample was characterized by electrochemical impedance spectroscopy. The diagrams were obtained for various immersion times in a 0.5 M NaCl solution for three different initial states of the same coil coating (as received, dried and dried after the impedance measurements). The aim of the study was to have a better knowledge of how the water uptake influences the coil coating physical properties and to extract relevant parameters of the ageing processes. From the high-frequency part of the impedance diagrams, the water uptake was calculated using a linear rule of mixtures. Two sorption regions were observed for the dried samples suggesting the presence of porosities already filled with ambient moisture for the as-received sample. It was shown that the water uptake was a slow process and, independently of the initial state of the sample, a saturation plateau was never reached, even after 456 h of immersion. A time constant, clearly visible on the phase angle of the impedance diagrams, was analysed through the dielectric permittivity formalism and attributed to the signature of the dielectric manifestation of the glass transition. This time constant was shifted to higher frequencies with increasing water fraction (increasing immersion time), consistent with a plasticization effect. This result was supported by differential scanning calorimetry measurements. Finally, the data obtained for the different initial states of the coating highlighted that, even if the water uptake was reversible, the sorption kinetics was different for the sample dried after the impedance measurements. This could be of importance in the degradation process of the coil coated steel.
Fichier principal
Vignette du fichier
Bonin_28410.pdf (3.48 Mo) Télécharger le fichier
Origin : Files produced by the author(s)

Dates and versions

hal-03388788 , version 1 (20-10-2021)

Identifiers

Cite

Pierre Bonin, Aurélien Roggero, Nicolas Caussé, Nadine Pébère, Dominique Thierry, et al.. Impedance analysis of the barrier effect of coil-coated materials: Water uptake and glass transition variations. Progress in Organic Coatings, 2021, 153, pp.106163. ⟨10.1016/j.porgcoat.2021.106163⟩. ⟨hal-03388788⟩
33 View
60 Download

Altmetric

Share

Gmail Facebook X LinkedIn More