Study on the mechanical properties of nanocellulose

Nanocellulose , as a novel biobased material with a wide range of sources, renewable and degradable sources, has attracted much attention in the fields of materials science and engineering in recent years. Among them, the excellent mechanical properties of nanocellulose are one of the key factors that can replace traditional materials and be applied to multiple high-end fields such as composite materials, packaging, and biomedical products.

1. Types and structural characteristics of nanocellulose

Nanocellulose mainly includes three categories: cellulose nanocrystals ( CNCs ), cellulose nanofibers ( CNFs ) and bacterial cellulose ( BC ). They all have high crystallinity and high aspect ratio, and their basic structural units are linear chains formed by β-D -glucose units connected by As the scale is reduced to the nanoscale, nanocellulose has a large amount of hydroxyl groups exposed to the surface, giving it good interfacial binding capabilities.β-1,4- glycosidic bonds.

2. Mechanical properties of nanocellulose

High-strength and high-modulus
nanocellulose exhibit significant strength and rigidity. The tensile strength of cellulose nanocrystals can reach 7.5 GPa , and Young's modulus is as high as 110–220 GPa , which is close to the level of steel; while cellulose nanofibers can still maintain high mechanical strength in wet states, indicating their application potential in wet environments.

The density of lightweight high-strength
nanocellulose is about 1.6 g/cm³ , which is much lower than that of metal materials, but its specific strength (strength / density) is extremely competitive and is suitable for lightweight structural materials, such as aerospace, automotive lightweighting and other fields.

The reinforcement effect is obvious.
Nanocellulose is used as a reinforcement phase in polymer matrix, which can significantly improve the tensile strength, bending strength and impact toughness of the composite material. For example, in PLA 、PVA , natural rubber and other systems, 160% is added。

Anisotropic properties
CNCs usually have highly anisotropic mechanical behavior, and their longitudinal strength is much higher than that of the transverse direction, making them suitable for directional arrangement or layered structure composite design.

Compared with rigid CNCs
, CNFs have better flexibility and ductility while maintaining a certain strength, and are suitable for base materials for bendable and wearable devices.

3. Factors that affect mechanical properties

Raw material sources and preparation methods: Different plant sources and treatment processes such as acidolysis, enzymatic lysis, mechanical methods will affect the crystallinity, aspect ratio and surface chemical characteristics, and thus affect the mechanical properties.

Moisture content: Nanocellulose is sensitive to humidity, and moisture will affect its hydrogen bond network structure, thereby changing its strength and rigidity.

Dispersed state and orientation arrangement: Good dispersed and ordered arrangement is conducive to the maximization of load transfer and enhancement effects.

Interface bonding: In composite materials, the strength of interface bonding between nanocellulose and the matrix is ​​an important factor affecting the final mechanical properties.

4. Application prospects and challenges

With its excellent mechanical properties, nanocellulose is widely used in high-strength composite materials, transparent films, 3Dprinting materials, biomedical materials and other fields. However, it is still facing challenges such as high cost of large-scale production, strong humidity sensitivity, and difficulty in dispersing control, and further optimization of the preparation process and functional modification methods are needed.

The mechanical properties of nanocellulose give it broad application prospects in the field of green materials. With the deepening of research and the advancement of industrialization technology, its substitution and enhancement role in various structural materials will become more prominent.

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I understand, below I will supplement you with a comparison table of key parameters for the mechanical properties of nanocellulose, and further expand its enhanced application in composite materials to help more comprehensively demonstrate its industrial value.

5. Comparison table of mechanical properties parameters of nanocellulose and other materials

Material Type	Tensile strength ( MPa )	Young's modulus ( GPa )	Density ( g/cm³ )	Specific strength ( MPa·cm³/g )	Feature Description
CNCs (cellulose nanocrystals)	7500	110–220	1.6	4687.5	Super high rigidity, suitable for enhanced use
CNFs (cellulose nanofibers)	200–2000	20–50	1.5–1.6	125–1250	Strong and tough, suitable for flexible applications
Stainless steel	500–800	200	7.9	63–101	Strong but heavy, traditional metal material
Carbon fiber	3000–5000	230–600	1.75–1.9	1578–2631	High performance reinforced materials, high cost
Polypropylene ( PP )	20–40	1–2	0.91	22–44	Commonly used plastics with low strength
Polylactic acid ( PLA )	50–70	3–4	1.25	40–56	Degradable polymers, average strength

6. Examples of reinforcement application of nanocellulose in composite materials

Polylactic acid ( PLA ) composites added
2 wt% CNCs to the PLA matrix , and the tensile strength increased from 55 MPa to 78 MPa , while the modulus increased by more than 30% . This reinforced composite material can be used in biodegradable packaging, medical implantation and other fields.

Natural rubber ( NR ) enhances
nanocellulose can combine well with natural rubber, significantly improving its tear strength and resistance to resilience. Used to prepare green tires, elastic seals, etc.

Due to its good mechanical properties and biocompatibility,
hydrogels and biostents are often used to enhance hydrogels such as gelatin, gelatin / sodium alginate, and to prepare 3Dbiostents with sufficient strength for tissue engineering and drug release.

Structural paper and transparent film material
nanocellulose can be used to prepare transparent and strong structural film materials, used in flexible electronic devices, sensors, etc., and has good bending resistance and high load bearing properties.

7. Conclusion

As a green high-performance material, nanocellulose has been widely verified in mechanical properties. Shows great potential in replacing traditional materials and developing new biodegradable high-strength materials. In the future, with the optimization of preparation technology and breakthroughs in interface engineering, nanocellulose is expected to become the core support of the new generation of sustainable reinforcement materials.

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Mechanical properties of nanocellulose and their application prospects

Nanocellulose is a nano-scale material made of natural cellulose finely processed, with high specific surface area , high crystallinity and unique mechanical properties. In recent years, nanocellulose has shown wide application prospects in many fields such as composite materials, biomedical products, sustainable packaging, electronic devices, etc., especially in the development of ' lightweight and high-strength ' materials.