Transparent tempo oxidized cellulose nanofibril (TOCNF) composites with increased toughness and thickness by lamination

Abstract

The favorable mechanical properties and performance of TEMPO-oxidized cellulose nanofibril (TOCNF) films has been limited by their brittleness and the incapability of obtaining thick enough materials for self-supported applications. In this study, lamination with room temperature curable epoxy was used to combat brittleness, increase thickness, and produce a more damage tolerant material. The effect of the volume fraction and layer thickness of both phases (e.g., TOCNF, epoxy), the number of layers, and the overall total thickness of the laminate, on the tensile and flexural properties are investigated. Lamination was successful at increasing the toughness and thickness of TOCNF composites, resulting in an increased work of fracture that was associated with fracture retardation by crack digression in three-point bending specimens. The ultimate tensile strength and Young’s modulus were higher for laminates with low volume fractions of epoxy although not statistically different than the neat TOCNF films, but decreased with increasing volume fraction of epoxy, and with increasing number of TOCNF layers.

Citation

Forti, Endrina S.; Moon, Robert J.; Schueneman, Gregory T.; Youngblood, Jeffrey P. 2020. Transparent tempo oxidized cellulose nanofibril (TOCNF) composites with increased toughness and thickness by lamination. Cellulose. 27(8): 4389-4405. https://doi.org/10.1007/s10570-020-03107-8.