New bio-based epoxide-amine coatings as replacements for BPA
A Diels Alder reaction was employed to prepare epoxy-functionalised tung oil (ETO). As a curing process, a primary diamine hardener (Jeffamine D2000) was used at four different temperatures ranging from 25 °C to 150 °C. Epoxide-amine nanocomposites were prepared with a 1:1 epoxy: amine molar ratio and additive of carbon nanoparticles (graphenes, carbon nanotubes (CNTs) and fullerenes).
The cured coatings were analysed by IR, DSC, TGA, and gel-content tests. Thermal stability of new coatings is observed up to 430 °C according to TGA analysis and these cured films displayed two glass transition points (Tgs) by DSC. While, of the three nano-composite incorporated systems, the graphene systems gave the maximum Tg in both phases, and the CNT-system exhibited a higher Tg and lowest weight loss with residues ranging up to 60% at 800 °C.
Good mechanical properties
The determination of the mechanical properties of the cured coatings was accomplished by pendulum hardness, pencil hardness, pull-off adhesion, cross-hatch adhesion, impact and reverse impact resistance tests. All the cured coatings have good mechanical properties in terms of hardness, cross-hatch adhesion and impact resistance. Generally, epoxide-amine nanocomposite coatings displayed better thermal and mechanical properties in comparison to epoxide-amine coatings.
The study has been published in Progress in Organic Coatings, Volume 165, April 2022.