Title: Nanocellulose biobased composite overlays

Abstract

Building on prior research of TEMPO-oxidized cellulose nanofibril (TOCNF) sheet lamination with room temperature curable epoxy, we elucidated further mechanistic phenomena by varying the toughness of each overlay and effected an improvement of the brittle/ductile interface adhesion. Previously we found that TOCNF laminates underwent brittle failure via slight delamination at the ductile to brittle layer interface followed by rupture of the brittle layer. As the ductile layer was reduced in thickness the tendency for delamination increased due to suppression of its energy storage resulting in greater stress transfer to the TOCNF layer to an extent that it underwent micro-cracking. In this recent study we reduced the brittleness of the TOCNF with a water-soluble polymer and evaluated the effects on performance and damage mechanism as a function of the ductile layer’s rigidity. In addition, we evaluated the effect of interfacial adhesion, using a silane coupling agent to improve the stress transfer between the ductile and brittle layers. These modifications were completed while maintaining optical appearance.