Improving the UV-stability of epoxy coatings

A method of improving the stability of epoxy coatings by using encapsulated halloysite nanotubes with organic UV-stabilisers and lignin has been decribed in a recently published paper.

The coated railing of a ship at sea.
The nanomaterial-loaded epoxy coating can greatly improve the composite's anti-corrosion ability. Image source: cocoparisienne - Pixabay (symbol image).

Epoxy coatings are used in a wide variety of applications due to their excellent chemical, thermal, and mechanical properties. However, their susceptibility to UV degradation has limited their use in exterior applications. Usually, organic UV absorbers and stabilisers are added to epoxy systems to improve their UV stability, but their performance decreases over time due to the degradation and loss of organic UV-stabilisers.

In a new study, a novel method was developed to encapsulate organic UV stabilisers and lignin (as a natural UV absorber) into halloysite nanotubes (HNTs). These nanotubes were added to an epoxy system (1−3 wt%) and their efficacy was evaluated before and after 840 h of accelerated weathering.

Significantly higher UV stability

Changes in physical, chemical, and thermal properties of coatings were measured. The results showed that epoxy samples containing 2 wt% HNT-encapsulated with organic UV-stabilisers, and samples containing 1 wt% HNTs encapsulated with lignin had significantly higher UV stability than epoxy resin prepared with the same concentration of these individual components (UV-stabilisers or lignin).

According to the researchers, the study demonstrates the efficacy of encapsulated HNTs, with UV stabilisers or lignin, in improving UV stability and extending service life of epoxy coatings.

The study has been published in Progress in Organic Coatings, Volume 158, September 2021.

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