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

Area of Science:

• Materials Science
• Biomaterials Engineering
• Sustainable Chemistry

Background:

• Lignocellulosic nanofibrils are promising renewable binders for structural composites due to their strength and eco-friendly properties.
• Understanding the adhesion mechanisms of cellulose nanofibrils (CNFs) is vital for optimizing composite performance and reducing manufacturing costs.

Purpose of the Study:

• To elucidate the morphology-dependent adhesion mechanisms of cellulose nanofibrils (CNFs) and lignin-containing cellulose nanofibrils (LCNFs).
• To investigate the impact of refinement and surface area on the adhesive properties of CNFs and LCNFs in a model paper substrate system.

Main Methods:

• Characterization of CNFs and LCNFs using optical, atomic force, and scanning electron microscopy across multiple length scales.
• Correlation analysis between fiber morphology (size, surface area) and adhesion strength in a model composite system.
• Evaluation of the effect of suspension stabilizers on LCNF adhesion.

Main Results:

• Refinement significantly alters the size distribution of CNFs and LCNFs, impacting their adhesive capabilities.
• Stronger adhesion was observed with decreased larger fiber sizes and increased relative fibril surface area.
• Lignin-containing cellulose nanofibril adhesion was hindered by flocculation, but improved with stabilizers.

Conclusions:

• Fiber morphology, particularly size and surface area, critically influences the adhesive performance of lignocellulosic nanofibrils.
• Suspension stabilizers can mitigate adhesion issues caused by flocculation in LCNFs, making them competitive with CNFs.
• This research provides fundamental insights for designing high-performance, sustainable composites using nanofibrillar binders.