Influence of synthetic and bio-based amine curing agents on properties of solventless epoxy varnishes and coatings with carbon nanofillers

Abstract Solventless epoxy varnishes and coatings were prepared using carbon nanotubes (CNT) and/or graphene (GNP) dispersions in a Bisphenol F-type epoxy resin, synthetic hardeners [tetraethylenepentamine, poly(oxyethylene)diamine, isophoronediamine, m-xylylenediamine] or bio-based amine hardener (Cardanol-based phenalkamine, abbreviationabbreviation: PAA). Room temperature cured coatings, containing 0.35 wt.% of CNT predispersed in PAA, showed outstanding combination of optical (i.e. high gloss and transparency, low haze in humid conditions) and electrostatic dissipative properties (surface resistivity ca. 5.5 × 10 7  Ω) in relation to the samples containing carbon nanofiller(s) dispersion in the epoxy resin or a synthetic amine. PAA-based coatings with the carbon nanofillers exhibited increased cupping resistance (+20% for samples with CNT) as well as high hardness and excellent adhesion to a glass substrate. The carbon nanofillers addition influenced on curing process and glass transition temperature (monitored using differential scanning calorimetry technique) of the epoxy varnishes and coatings as well.