Application of cellulose nanofibers in composite material reinforcement

Cellulose Nanofibers (CNF) has become an important enhancer in the field of composite materials due to its excellent mechanical properties, light weight and renewability. With the growth of demand for green materials, the application potential of cellulose nanofibers in composite materials is constantly expanding.

Characteristics of cellulose nanofibers

High mechanical properties CNF has high strength and high modulus, its tensile strength can reach 1.5-3 GPa, its elastic modulus is approximately 140 GPa, and its density is only 1.5 g/cm³, making it an ideal choice for lightweight composite materials. .

Good dispersion and interface binding force The high specific surface area of ​​CNF (approximately 50-150 m²/g) and rich hydroxyl structure enable it to form strong bonds with a variety of matrix materials (such as polymers, rubbers), improving composite materials overall performance.

Renewable and Degradable As a natural source material, CNF is not only environmentally friendly, but can also degrade after use, reducing environmental burden. Reinforcement in composite materials

Improved mechanical properties

Rigidity and strength : After the addition of CNF, the tensile strength and modulus of the composite material are significantly improved. For example, after adding 10 wt% CNF to a polylactic acid (PLA) matrix, its strength can be increased by more than 50%, and the elastic modulus will be increased to 4 GPa.

Toughness enhancement : The flexibility of nanofibers increases the fracture toughness of composite materials by about 30%.

The low density characteristics of the lightweight design of CNF enable it to reduce the weight of materials while maintaining high strength, which has important application value in the aerospace and automotive fields.

Thermal Stability and Flame Retardancy In some substrates, the introduction of CNF can increase the thermal decomposition temperature of the material by 20-30 °C and enhance the flame retardancy of the material by forming a dense carbonized layer.

Gas barrier properties The dense network structure formed by CNF can reduce the oxygen transmittance of composite materials to below 0.1 cm³/(m²·day·atm), making it ideal for food packaging applications.

Application areas

The automotive industry CNF enhanced composite materials can be used to manufacture automotive interior and exterior trims such as instrument panels, door panels and bumpers, which not only reduce vehicle weight but also improve durability and fuel efficiency.

The construction field is used to reinforce concrete and plastic building materials, with tensile strength increased by 25-40% and impact resistance increased by about 15%.

Electronics Industry In flexible electronic devices, CNF-based composite materials can be used as the substrate for circuit boards and displays, both lightweight and high strength, and their tensile strength is up to 200 MPa.

The packaging industry's cellulose nanofiber reinforced composite materials have high gas barrier properties and excellent mechanical properties, which are very suitable as food packaging materials, extending shelf life and reducing plastic use.

Technical parameters

Fiber diameter and length : The fiber diameter is about 5-20 nanometers and the length range is 500-2000 nanometers, providing an extremely high aspect ratio, which facilitates the formation of a reinforced network.

Thermal stability : Thermal decomposition temperature (T₍₅) is 260-300 °C, showing excellent thermal stability.

Hygroscopicity : The moisture absorption rate under equilibrium humidity conditions is about 8-12%, and it varies according to the environment humidity.

Mechanical enhancement effect :

In the PLA matrix, 5 wt% of CNF was added, and the tensile strength was increased by about 30% and the elastic modulus was increased by 20%.

In the epoxy resin matrix, 2 wt% CNF was added, and the impact resistance was improved by 15%.

Technical challenges and future development

Dispersion and homogeneity The uniform dispersion of CNF in the matrix is ​​still a technical difficulty, and further optimization of dispersion technology is needed to reduce agglomeration.

The current production cost of CNF on a large scale is relatively high (about USD 10-20/kg), which limits its large-scale commercial application. With the improvement of the preparation process and the reduction of raw material costs, its applications will become more extensive.

Interface binding force optimization Through chemical modification or surface treatment, further enhancing the interface binding force between CNF and the matrix is ​​the focus of research.

Conclusion

Cellulose nanofibers have shown great application potential in the field of composite material reinforcers. With the increasing demand for green materials and lightweighting, CNF is expected to play an important role in automotive, construction, electronics and packaging. Through technological innovation and production process optimization, CNF's economy and performance will be further improved, bringing revolutionary changes to the composite materials industry.