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

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.

Automated summary

The use of lignocellulosic nanofibrils as adhesive binders in structural composites is a growing field due to their renewable, recyclable, and strong properties. Understanding the adhesion mechanisms of cellulose nanofibrils is crucial for optimizing performance and production costs, with strong adhesion linked to decreased fiber size and increased relative fibril surface area. The addition of suspension stabilizers can improve adhesion of lignin-containing cellulose nanofibrils to levels comparable to pure cellulose nanofibrils.