Preparation of bionanocomposite coatings from tung oil treated with a diamine and a triamine as alternatives for bisphenol A (BPA)

Abstract

The aim of this study is to obtain new bio-based epoxide-nanocomposite coatings as an alternative to BPA for aluminum surfaces and compare new bio-based epoxide-amine coatings with their nanocomposite coating derivatives (graphene, CNT, and fullerene). Moreover, the comparison of epoxide-triamine nanocoating with epoxide-diamine nanocoatings are also given. As replacements for BPA, new bio-based epoxide-amine coatings and their nanocomposite coating derivatives including graphenes, carbon nanotubes (CNTs) and fullerenes were prepared with an epoxide tung oil (ETO) and Jeffamines (T403 and ED900) and, their thermal and mechanical properties have been compared, as well.In the first step, epoxy functionalized tung oil (ETO) was synthesized via the Diels-Alder reaction. Subsequently, these new epoxide-nanocomposite coatings were successfully prepared from the reaction of an epoxy functionalized tung oil (ETO) and two different polyether amines (Jeffamines T403 and ED900) as cross-linking agents, premixed with graphene, fullerene, and carbon nanotubes (CNTs) as nanoparticles. Four different curing temperatures were applied ranging from 25 °C to 150 °C. Epoxide-amine nanocomposites were prepared with a 1:1 epoxy: amine molar ratio and additive of 1% of carbon nanoparticles (graphenes, carbon nanotubes (CNTs) and fullerenes).Epoxide resin and the new nanocomposites were identified via 1H NMR, 13C NMR, IR, DSC and TGA analyses. Thermal stability of new coatings is observed up to 420 °C according to TGA analysis and these cured films displayed no glass transition points (Tgs) by DSC, except epoxide-diamine nanocoatings prepared with graphene (ETO-ED900-Graphene).The determination of the mechanical properties of the resulting nano coatings was accomplished by pendulum hardness, pencil hardness, cross-hatch adhesion, pull-off adhesion, impact and reverse impact resistance tests. New epoxide-amine nanocomposite coatings exhibit excellent thermal stability. All the cured films showed good adhesion, hardness, and impact resistance properties. Generally, epoxide-amine nanocomposite coatings displayed better thermal and mechanical properties in comparison to epoxide-amine coatings.They can be used as alternative coatings instead of BPA based epoxy resins in various coating systems in automobile, ships, aerospace, food and beverage industries due to their excellent thermal stability and good mechanical properties.