Natural fibers have been used as reinforcing materials for more than 3,000 years. Over the past five years, there has been a resurgence of interest in natural fiber composites due to concerns about improving and stimulating rural economies, reducing dependence on petroleum-based materials, and adopting responsible materials management practices at the end of their useful life.
Natural fiber composites not only provide superior performance at lower manufacturing costs; they also help reduce greenhouse gas production and protect the environment.
What are natural fiber composites?
Scientists around the world are devising effective ways to reduce energy consumption and use materials with better properties than traditional industrial components. Composite materials have long been a focus of attention because they can be modified to meet application requirements.
A research article in Materials Today: Conference Proceedings notes that modification of the properties of composites for high-strength applications is often accomplished using the common practice of reinforcement, usually through the addition of fillers or fibers. Natural fibers are obtained from natural resources such as bark and twigs, as well as other organic sources. The addition of such natural fibers makes composites environmentally friendly and significantly reduces manufacturing costs, as natural fibers are usually found in large quantities in the environment.
Natural fiber composites: the first choice for automotive applications in recent years
The current era of Manufacturing 4.0 is focused on sustainability, automation and efficient manufacturing. Almost all industries are looking at utilizing sustainable materials to replace traditional components.
There has been a trend in the automotive industry to focus on natural material sources. In this context, natural fiber composites are receiving increasing attention. The use of composites based on natural fibers in different components of automobiles has the potential to achieve weight reductions of up to 34%; as mentioned in an article published in Engineering Science.
Natural flax fibers are used to make hoods for modern vehicles, and research involving structural analysis has made them safe and durable. Mechanical testing of hybrid natural composites consisting of coir fibers and epoxy-reinforced carbon fibers demonstrated the feasibility of using a variety of fibers to construct bicycle helmet covers, automobile floors and roofs.
Design and analysis of vehicle hoods using vinyl ester matrix composites reinforced with flax fibers have shown a 30 percent weight reduction compared to steel hoods. Luxury automotive brand Audi is using flax and sisal fibers in the production of door trim.
Natural fiber composites for bulletproof undershirts
National armed forces personnel require essential personal protective equipment on the battlefield, including bulletproof undershirts. The materials within these undershirts are essential to minimize the kinetic energy generated by the penetration of projectiles. As an alternative to composites, natural fibers can be used as a replacement for Kevlar in these undershirts. This significantly reduces manufacturing costs while maintaining the same level of safety.
Researchers from Indonesia have published an article in Defense and Security Studies highlighting the importance and effectiveness of five natural fibers in composites for bulletproof undershirt applications. The researchers analyzed pineapple leaf fibers, water hyacinth fibers, salad leaf fibers, hemp fibers, and bamboo fibers according to National Institute of Justice (NIJ) standards.
The research team conducted experimental tests by firing bullets at specific speeds from a specified distance to determine the effectiveness of natural fibers in bulletproof undershirt applications. Pineapple leaf fibers were used in thicknesses of 10 mm, 15 mm and 20 mm. Each type of undershirt was tested and the results showed that the bullets penetrated the undershirt.
The depth of penetration was 58 mm, 10 mm and 4 mm respectively. These values are within the danger limits, exceeding the thickness of the undershirt and causing injury to personnel. Defense standards specify that bullets cannot penetrate the thickness of the undershirt. Once penetrated, the undershirt becomes ineffective and cannot be used by military personnel - an alternative material to bulletproof undershirts. Therefore, pineapple lead fiber cannot be used to make bulletproof vests.
The same test was performed on the remaining four natural fiber composites. Bullets failed to penetrate the body armor. This indicates that bamboo, hemp, water hyacinth and saracenic fibers have excellent tensile properties and impact strength. Therefore, these materials can be safely used in bulletproof undershirts.
Natural fiber composites: transforming the construction industry
Traditionally, cement and concrete have been used for construction all over the world. However, recent scientific advances have led to the development of materials with enhanced thermal and mechanical properties. These materials, known as biocomposites, are made from natural fibers and can significantly reduce the carbon footprint of buildings. Biocomposites are categorized into two groups: structural and non-structural natural composites.
The structural composite type is suitable for robust applications such as bridges, while the latter is used for sliding doors, panels, exteriors and windows.
According to an article published in Engineering Outcomes, these materials have excellent thermal and acoustic insulation properties and can be used as an environmentally friendly alternative to traditional building materials such as plastic or metal. They are particularly good for reinforcing thin-walled structures and contribute to eco-design principles. Bamboo, sisal and coir fibers are examples of natural elements used in these composites for a variety of construction purposes, especially roofing.
In addition, natural fiber-reinforced composites (NFRCs) have a variety of applications in the construction and furniture industries, as highlighted by research published in the journal Polymer. These composites are used to produce door frames, windows, floor mats, partitions and ceilings.
In addition, they are useful in the manufacture of furniture such as tables, chairs and kitchen tools. In addition to excellent durability, NFRC products are beautiful and very elegant.
Discoveries
Researchers are working to discover and develop new natural fibers to make new high-quality composites for industrial applications. A team of researchers published a study in Heliyon focusing on the development of a new cellulose-rich natural fiber.
The team performed standard tests and Soxhlet extraction techniques to determine the chemical composition of the fiber. The new fiber is rich in cellulose, with tests showing a concentration of about 79.32 percent alpha-cellulose, and the fiber also contains 8.01 percent hemicellulose. The lignin concentration was 6.77% and trace amounts of ash were also present.
The team used standardized X-ray diffraction analysis to determine the crystalline properties of the fibers. The crystallinity of the fibers was 89%.
FTIR analysis confirmed the presence of the expected functional groups. Thermogravimetric analysis was performed to determine the thermal properties of the fibers, especially thermal stability. Maximum degradation of the fiber occurred at 358°C. These properties make the new fibers suitable for a variety of applications, including composites, textiles, cellulose nanomaterials, activated or conductive carbon, and reinforcement of biomaterials.
In short, the scientific community is committed to the use of natural fibers to achieve the SDGs. The use of natural fiber composites will significantly reduce global warming and supply chain issues in various industries such as the automotive industry.
