• The tendency to absorb moisture, affecting dimensional stability and durability.
• Lower thermal and mechanical resistance compared to more conventional composites such as carbon fiber.
• Variability in mechanical properties, as they are natural materials exposed to environmental conditions and require harvesting and processing.

Interior carpeting of a cars door made by a biocomposite of hemp fibres and polyethylen. Credit: Christian Gahle, nova-Institut GmbH.

Technological Advances in NFCs: Treatments and Improvements

Recent research projects have focused on overcoming the limitations of Natural Fiber Composites (NFCs) in the automotive sector. Let’s see what those key advancements are.

Physical Treatments

• Plasma and corona treatment: These methods modify the surface energy of fibers, improving their adhesion to the polymer matrix without altering their chemical composition. This enhances resin compatibility and increases mechanical strength.
• UV and heat treatment: UV and heat exposure minimizes moisture absorption, enhances thermal stability, and extends durability under demanding conditions.

Chemical Treatments

• Alkalization (NaOH): Sodium hydroxide treatment removes impurities such as lignin and hemicellulose, increasing the exposed cellulose content and improving adhesion with the polymer matrix. This results in higher mechanical strength and reduced water absorption.
• Silane and acetylation: Silane coupling agents and acetylation promote covalent bonding between fibers and the matrix, reducing hydrophilicity and enhancing moisture resistance and material durability.
• Peroxides and benzoylation: These treatments generate free radicals that improve adhesion between the fiber and matrix, increasing the composite’s thermal and mechanical resistance. They also reduce fiber degradation and enhance structural stability.

Nanoparticle Incorporation (TiO₂, ZnO, SiO₂)

The integration of nanoparticles into NFCs creates a protective barrier that minimizes moisture absorption and reinforces the material’s structure. Additionally, these additives improve UV resistance and thermal degradation resistance, extending the composite’s lifespan.

Bright future

These advancements have made NFCs more stable, durable, and suitable for a wider range of automotive applications. While the industry has primarily employed NFCs for vehicle interiors, an increasing number of structural and bodywork components are now being developed using these materials.

Just a few years ago, the idea of NFCs in high-performance applications seemed unfeasible, but today, Formula 1 teams and other motorsport disciplines are experimenting with NFC-based components. At Managing Composites, we firmly believe that with the right engineering approach, there are very few limitations for NFCs. This is why we have taken on the challenge from LIUX to develop the monocoque chassis of their BIG model using linen fiber.

LIUX BIG monocoque chassis made of flax fiber. Credit: LIUX

When Are NFCs the Best Option?

Returning to the initial question—when should NFCs be chosen? In our view, nearly any development is feasible with NFCs today. Synthetic materials, especially high-performance composites, still hold mechanical advantages that make them the preferred choice when absolute performance is the only priority, particularly for structural components.

However, for non-structural developments and industrial or commercial applications, NFCs are becoming an increasingly attractive option. Thanks to continuous applied research, their performance is improving daily. When sustainability factors are introduced into the equation, NFCs often become the winning choice in an ever-growing number of scenarios.

Ultimately, advancements in fiber treatments and resin formulations are driving NFCs toward broader adoption in the automotive industry. Their use will continue to rise, particularly in structural and semi-structural components where sustainability is a key driver. As the performance gap between NFCs and traditional composites narrows, we will see them play an increasingly prominent role in future automotive designs.

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