Solutions for Cellulose Nanofibers

Importance of the Topic

Cellulose nanofibers (CNFs) are plant-derived carbon-neutral materials that combine light weight, high strength, thermal resistance, and elasticity.
They are abundant and biosynthesized via photosynthesis, offering a sustainable route to bio-based materials that address environmental challenges such as global warming.
Comprehensive characterization of CNF properties—including morphology, dispersibility, surface chemistry, crystallinity, rheology, and mechanical performance—is critical to unlocking their full potential in high-tech and industrial applications.

Objectives and Study Overview

This summary consolidates key analytical approaches for CNF described in Shimadzu application notes.
The goals are to present methods for:

• Monitoring fiber disintegration and size reduction during mechanical defibration.
• Evaluating dispersibility and surface functional groups in solution and film states.
• Measuring fiber dimensions rapidly and automatically.
• Assessing crystal structure, rheological behavior, and mechanical performance in composites.

Such data guide process optimization, quality control, and product development for CNF-reinforced materials.

Methodology and Instrumentation

Shimadzu instruments and methods employed include:

• Scanning Probe Microscope (SPM-9700HT) and Laser Scanning Microscope (OLS Series) for high-resolution 3D morphology and automated particle analysis of fiber length/width.
• UV-Vis spectrophotometers (UV-2600) and integrating sphere (ISR-2600 Plus) for linear and total light transmittance to probe dispersibility and film transparency.
• FT-IR (IRSpirit/IRTracer-100 with ATR) to identify cellulose, carboxymethyl, amide, and other surface functional groups.
• Nano Particle Size Analyzers (IG-1000 Plus with induced grating; SALD-7500nano with laser diffraction) to rapidly determine particle size distributions in aqueous CNF suspensions.
• X-Ray Diffractometer (XRD-7000) for Segal crystallinity index of CNF sheets.
• SFT-4500 Nano Search Microscope combining LSM and SPM for wide-range imaging and 3D mapping of mechanical properties (Young’s modulus) in CNF/polymer composites.
• Constant Force Extrusion Capillary Rheometer (CFT-EX Series) for melt viscosity and shear-rate behavior of CNF-reinforced thermoplastics to predict molding conditions.
• Universal Testing Machine (AGS-X) with three-point bend jig and deflectometer for flexural modulus and strength of CNF-reinforced plastics and foams.

Main Results and Discussion

• Mechanical Defibration by SPM/LSM: Observed size reduction from bundled fibers to ~12 nm average diameter after five passes; high-resolution SPM showed individual CNF diameters ~4 nm.

• Dispersion and Surface Chemistry: UV-Vis showed cloudy CNF solutions with low linear transmission; total light transmission remained high. FT-IR ATR revealed characteristic O–H and C–O peaks for cellulose, COO– groups in CMC, amide bands in chitin, and similar spectra for fermented nanocellulose.

• Fiber Dimension Measurements: Manual SPM measured various CNF grades (lengths 1.5–2.2 µm; widths 8–11 nm). Automated SPM extracted 2300 TOCN fibers, finding average length ~145 nm and width ~1.7 nm.

• Particle Sizing and Induced Grating: Sonication converted bundles to mono-dispersed fibers; IG peaks shifted from 30 nm to 15 nm with extended treatment, correlating with SPM results.

• Crystallinity: XRD Segal method yielded CNF crystallinity indices of 76–86% depending on source.

• Composite Imaging and Mechanics: Nano Search SFT images revealed intertwining of CNF/PVP fibers and phase mapping distinguished polymer and fiber regions; 3D Young’s modulus mapping showed distinct mechanical zones for CNF and polymer.

• Melt Rheology: CFT-EX rheometry showed increased viscosity for CNF5%/HDPE compared with GF10% or neat HDPE; shear thinning preserved processability at high shear rates.

• Flexural Properties: Three-point bend tests demonstrated higher flexural modulus and strength with 5% CNF addition; CNF-reinforced HDPE foams exhibited finer, more uniform voids and reduced strength variation.

Benefits and Practical Applications

• Optimized CNF production and defibration protocols based on morphology monitoring.
• Quality control of CNF dispersions and films for coatings, barrier materials, and composites.
• Rapid fiber sizing for large-scale production and in-line monitoring.
• Guidance for injection and extrusion molding conditions through melt rheology data.
• Design of high-performance CNF-reinforced plastics, rubbers, foams, and films.
• Correlating advanced analytical techniques with simpler, lab-ready measurements to accelerate commercialization.

Future Trends and Opportunities

Emerging areas include:

• Integration of real-time, in-line sensors and machine learning for adaptive process control.
• High-throughput screening of CNF functionalization and composite formulations.
• Advanced 3D printing and additive manufacturing of CNF-based bio-composites.
• Development of standardized CNF characterization protocols for global regulatory and quality assurance.
• Exploring new biomass sources and green chemical routes for tailored CNF properties.

Conclusion

A multi-technique analytical approach is essential for fully characterizing CNF properties and guiding their industrial application.
Shimadzu’s suite of advanced instrumentation—ranging from nanoscale imaging and spectroscopy to rheology and mechanical testing—provides a comprehensive platform for CNF research, quality control, and process optimization.
These capabilities support the development of sustainable, high-performance CNF-reinforced materials for diverse industries.