Optimizing lignocellulosic nanofibril dimensions and morphology by mechanical refining for enhanced adhesion

Peter V Kelly; Douglas J Gardner; William M Gramlich

doi:10.1016/j.carbpol.2021.118566

Optimizing lignocellulosic nanofibril dimensions and morphology by mechanical refining for enhanced adhesion

Carbohydr Polym. 2021 Dec 1:273:118566. doi: 10.1016/j.carbpol.2021.118566. Epub 2021 Aug 18.

Authors

Peter V Kelly¹, Douglas J Gardner², William M Gramlich³

Affiliations

¹ Department of Chemistry, University of Maine, 178 Munson Road, Orono, ME 04469, USA.
² School of Forest Resources, University of Maine, 5755 Nutting Hall, Orono, ME 04469, USA; Advanced Structures and Composites Center, University of Maine, 35 Flagstaff Road, Orono, ME 04468, USA.
³ Department of Chemistry, University of Maine, 178 Munson Road, Orono, ME 04469, USA; Advanced Structures and Composites Center, University of Maine, 35 Flagstaff Road, Orono, ME 04468, USA. Electronic address: william.gramlich@maine.edu.

PMID: 34560977
DOI: 10.1016/j.carbpol.2021.118566

Abstract

Using lignocellulosic nanofibrils as adhesive binders in structural composites is a growing field of interest attributable to their renewability, recyclability, and strength. A fundamental understanding of their adhesion mechanisms is crucial to tailor performance and optimize production costs. These mechanisms were elucidated by studying the morphology dependent adhesion in a model system composed of cellulose nanofibrils (CNFs) at different degrees of refinement and porous paper substrates. CNFs and lignin containing cellulose nanofibrils (LCNF) were characterized at different length scales using optical, atomic force, and scanning electron microscopy, revealing a complex distribution of sizes, spanning the macroscale to the nanoscale, which are modified unequally by refinement. Strong adhesion was correlated to a decrease in fiber size on the largest length scale and with an increase in relative fibril surface area. Flocculation hampered effective LCNF adhesion, but adding suspension stabilizers improved adhesion to levels comparable to CNF.

Keywords: Adhesion measurements; Fibril morphology; Lignocellulosic nanofibrils; Mechanical refinement; Multi-scale characterization; Structure-property relationships.