Cardanol-based epoxy anti-corrosion coatings

A new paper shows the fabrication of graphene oxide-modified self-healing microcapsules for Cardanol-based epoxy anti-corrosion coatings.

Cardanol, a well-known bio-based precursor is mainly extracted from nuts of cashew fruits and discarded as waste products from cashew industries. Image source: LoggaWiggler - Pixabay (symbol image).

For the study, graphene oxide (GO) modified microcapsules have been developed for use in self-healing Cardanol-based epoxy anti-corrosion coatings on steel substrates. The microcapsules had a polymethyl methacrylate (PMMA) shell, covered with aminated GO flakes and contained either of the two complementary healing agents mixed with nanosized GO flakes. One set of capsules contained epoxidised nanosized GO and Cardanol-based epoxy resin, while the other contained aminated nanosized GO and Cardanol-based amine curing agent.

Excellent anti-corrosion properties

The Cardanol-based coatings containing various fractions of up to 20 wt% microcapsules in their stoichiometric ratio showed excellent anti-corrosion and self-healing properties. It was found that, after 60-day immersion in 3.5 wt% NaCl solution, the low-frequency impedance modulus |Z|0.01Hz of the Cardanol-based coating containing GO-modified microcapsules was three orders of magnitude higher than that of the systems with capsules without GO. After scratching the coating containing 20 wt% GO-modified microcapsules and exposing it to an aqueous 3.5 wt% NaCl solution, the |Z|0.01Hz of the Cardanol-based coating returned over a period of 7 days to the original value.

The study has been published in Progress in Organic Coatings, Volume 183, October 2023.

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