Nanocellulose ( Nanocellulose ) is a cutting-edge functional material that is currently being developed in the global new material field. With its high specific surface area, high mechanical strength, reproducibility, low density and excellent interface properties, it has shown great application potential in composite materials, electronic materials, medical materials, environmental engineering and other fields. The homogenization method ( High-Pressure Homogenization, HPH ) is currently the leading technical route in the industry for the preparation of cellulose nanofibrils ( CNF ) due to its mature process, high nanotechnology efficiency, continuity and scale.

Based on the perspectives of materials science, chemical engineering and equipment engineering, this article systematically explains the mechanism, process control points, equipment parameters, structural characteristics and industrialization value of nanocellulose prepared by the homogeneous method , providing professional reference for industry research and technical cooperation.

1. Engineering analysis of the nanonization mechanism using the homogeneous method

The core of preparing nanocellulose by the homogeneous method lies in the transient energy density release under high pressure conditions . The cellulose slurry passes through the micron-level homogenization valve ( Gap Valve ) at high speed under a high pressure of 800-2000 bar , and the following three types of dominant forces occur instantly:

1. High Shear

The fluid is sheared at high speed in the narrow channel, causing the fiber to undergo continuous splitting along the axial direction, providing primary fragmentation for nanotechnology.

2. Cavitation

The high-speed fluid forms a large number of microbubbles due to the sudden pressure drop, which instantly collapses in the subsequent high-pressure zone, producing local micro-explosion with tens of millions of accelerations, effectively peeling off the cellulose crystalline and amorphous areas.

3. Micro-Jet Impact

The high-speed microjet impacts the solid-liquid interface to further nanonize the fibers to enhance the uniformity of fiber distribution.

The superposition of these effects gradually peels cellulose from the micron scale into a long-term stable and dispersed nanofiber network structure. Its final particle size can reach an ultra-aspect ratio structure with a diameter of 20–50 nm and a length of several microns.

2. Process flow and key parameter control of homogenization method

( 1) Cellulose pretreatment technology

Pretreatment is the core step that determines energy consumption, fiber fineness and product stability. Common methods include:

TEMPO oxidation modification : introducing a carboxyl group at the C6 position to improve the electrostatic repulsion between fibers and reduce energy consumption by 60–80% .

Enzymatic hydrolysis ( Endoglucanase ) : selectively degrades the amorphous region and improves the dispersibility of cellulose.

Alkalization : Promote fiber swelling and enhance dissociation efficiency after homogenization.

Through chemical or enzymatic pretreatment, the number of final homogenization times can be 20 reduced from more than 1 to 3-10 times, making the process more industrially competitive.

( 2) High-pressure homogenization process (HPH)

Key process parameters include:

parameter	Typical range	Process impact
homogeneous pressure	800–2000 bar	Determine nanotechnology efficiency and fiber diameter
Homogenization times	3–20 times	Determine fiber fineness and network strength
Temperature control	＜ 55℃	Avoid thermal degradation of fibers and ensure stable viscosity
Solid content	1–3%	Taking into account energy consumption and equipment safety

Under the action of high-pressure shearing and cavitation, cellulose is gradually transformed into transparent or translucent nanocellulose gel, which has a typical three-dimensional network structure.

( 3) Product post-processing and structural control

Post-processing can customize the product structure according to the final application, including:

Ultrasonic dispersion : further reduce agglomeration and improve transparency

Lyophilization / spray drying : Preparation of CNF aerogel or dry powder materials

Surface functionalization : introducing carboxyl / hydroxyl / sulfonic acid groups to enhance interfacial compatibility

Narrow particle size distribution control : fine classification through screening and centrifugation

These treatments make CNF more suitable for high-end scenarios such as composite materials and conductive films.

3. Performance characteristics of nanocellulose prepared by homogeneous method

Homogenized CNF has a variety of typical structural properties:

Large aspect ratio ( >100 ) : conducive to enhancing the interface mechanical properties of composite materials

High specific surface area ( >100 m²/g ) : Provide more reactive sites

Form a stable hydrogel structure : with excellent rheological properties and thixotropy

High transparency : suitable for transparent films and electronic materials

Can form strong interface interaction with polymer materials

Its performance is far superior to traditional microfibrillated cellulose ( MFC ).

4. homogeneous CNF Industrial application direction of

With its high-performance structural features, CNF has achieved engineering applications in multiple industrial fields:

1. High performance composite materials

Significantly enhance the mechanical properties and heat resistance of polylactic acid ( PLA ), polyurethane, epoxy resin, etc.

2. Electronic materials

Flexible transparent substrate

Conductive composite film

Separator materials (such as lithium battery separator reinforcement layer)

3. Biomedical materials

Tissue engineering scaffold

Antibacterial / pro-healing hydrogel

Smart drug delivery system

4. Environmental protection and energy materials

High Flux Filtration Membrane

porous adsorbent

Functional airgel materials

5. Food and daily chemicals

As a natural thickener, stabilizer, and thixotropic agent, it has entered the practical stage.

5. Technology Development Trends and Industrial Value

With the upgrade of equipment engineering technology, breakthroughs in pre-treatment technology and growth in industrial demand, homogeneous nanocellulose is developing in the following directions:

Low energy consumption homogenization equipment (next generation HPH system)

High solid content nanotechnology (solid content ≥5% )

Customized functional modification of nanocellulose

High-end applications in new energy and semiconductor materials

Integration of continuous large-scale production and smart factories

The reproducibility and material performance advantages of homogeneous CNF will continue to promote its industry growth worldwide.