Nanocomposites from Clay, Cellulose Nanofibrils, and Epoxy with Improved Moisture Stability for Coatings and Semi-Structural Applications

A new type of high reinforcement content clay-cellulose-thermoset nanocomposite was proposed, where epoxy precursors diffused into a wet porous clay-nanocellulose mat, followed by curing. The processing concept was scaled to > 200 µm thickness composites, the mechanical properties were high for nanocomposites and the materials showed better tensile properties at 90% RH compared with typical nanocellulose materials. The nanostructure and phase distributions were studied using transmission electron microscopy; Young’s modulus, yield strength, ultimate strength and ductility were determined as well as moisture sorption, fire retardancy and oxygen barrier properties. Clay and cellulose contents were varied, as well as the epoxy content. Epoxy had favorable effects on moisture stability, and also improved reinforcement effects at low reinforcement content. More homogeneous nano- and mesoscale epoxy distribution is still required for further property improvements. The materials constitute a new type of three-ph...