Combined studying of coil-coated steel ageing
In a new study, ex situ FTIR-ATR and in situ EIS was used to investigate the chemical and physical structure of polyester/melamine coil-coated steel during complex and representative ageing conditions.

The samples were first subjected to a QUV accelerated weathering test for 250 h up to 2000 h, followed by immersion in a 0.5 M NaCl solution to assess water uptake and polymer matrix plasticization. FTIR analyses revealed chemical degradation, including chain scission and the formation of polar groups, between 500 h and 2000 h of QUV exposure. Degradation effects were observed throughout the whole topcoat, with more significant degradation occurring near the surface. EIS measurements indicated greater water uptake with increasing QUV exposure.
Identified ageing markers
As the reseachers emphasise, the polymer maintained effective protective properties despite the UV-induced degradation, evidenced by the high low-frequency impedance unaffected by UV exposure or immersion duration (1 week). They point out that their methodology successfully identified ageing markers, providing a framework for studying UV degradation mechanisms, water uptake, and polymer mobility in anticorrosion coatings.
The study has been published in Progress in Organic Coatings, Volume 199, February 2025, 108953.
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