Natural Fibers to Composites

The increasing cognizance of the ecological harm produced by synthetic materials has given rise to the rapid increase in the consumption of environmental-friendly materials. There has been a great upturn in demand for marketable consumption of ecological natural fiber-based composites in several manufacturing industrialized sectors, such as automotive, building construction, furniture, and aerospace in recent years. Natural environment-friendly fibers are renewable resources which are abundant in nature with benefits of low cost, lightweight, renewability, biodegradability, and higher specific characteristic as compared to synthetic materials. The enduring feasibility of natural fiber-based composite materials has increased their usage in several manufacturing sectors. In this chapter, different sources of natural fibers, their characteristics, and morphological structure are discussed in detail. Moreover, the primary use of ecological natural fibers, as well as their effective utilization as reinforcement in polymer composite materials were also summarized.

Natural fiber-reinforced composites (NFRC) are being widely researched to provide a sustainable and eco-friendly solution. Natural fibers are an annually renewable resource and provide additional advantages of low density and biodegradation. However, there are certain limitations associated with these fibers, e.g., moisture absorption, flammability, low strength, etc. To overcome these limitations, natural fibers are subjected to various physical and chemical treatments. The current chapter reviews different treatments used for natural fiber and their effect on the performance of NFRC. The chemical treatments for hydrophobicity include silane treatment, acetylation, etherification, benzoylation, dicumyl peroxide, and enzyme and peroxide treatment. Fiber treatments for other functional properties including flame retardancy, electrical conductivity, and antipathogen properties are also discussed in the chapter.

Three-dimensional (3D) natural fiber reinforced polymer composite materials are gaining popularity in the modern world due to their environment-friendly nature, lightweight, low cost, life-cycle superiority, and biodegradability. Natural fiber reinforced composites are widely used in various engineering applications, and this research area is constantly evolving. However, due to the inherent properties of natural fibers, researchers face numerous challenges in the development and application of natural fiber reinforced composites. These difficulties include fiber quality, thermal stability, water absorption capacity, and compatibility issues with polymer matrices. Ecological and financial concerns are stimulating new research areas in the field of natural fiber reinforced composites. Also, significant research has been conducted recently to improve the performance of natural fiber reinforced composites. This chapter explains the types of reinforcement and composite fabrication techniques used for 3D natural fiber reinforced composites. Also, discussed the literature survey of 3D natural fiber reinforced composites to examine the effect of binder yarn, stuffer yarn, and weave design on the mechanical performance of composites. Furthermore, 3D woven-shaped preforms and their associated composites are also discussed.

Thermoplastic composites are an area of growing interest due to increasing environmental awareness as they are recyclable. However, high melt viscosities and poor fiber matrix adhesions lead to quality and performance issues. The commingling technique is a considerable solution to this problem; hence, textile preforms are engineered by utilizing both fibers and thermoplastic matrix simultaneously in the dry state. Such dry prepregs are capable of being converted into composites through the application of heat and pressure. Commingled prepregs provide close fiber-matrix physical contacts resulting in better interfaces and wetting characteristics. The chapter discusses possible techniques for prepregs manufacturing at fiber, yarn, and fabric levels. Thermoplastic commingled composites fabrication techniques have also been elaborated, including thermoforming and pultrusion. The impact of commingling on mechanical performance parameters is highlighted, and possible commingling routes are predicted to achieve endurable characteristics.

Fiber reinforced polymer composites (FRPC) offer advantages including lightweight, flexibility of design, ease of fabrication, long service life, superior mechanical performance, etc., over conventional materials such as steel, aluminum, wood, etc. Their market has grown significantly ($101.6 billion by 2026) in automotive, aerospace, sports, and construction in the last decade. In spite of numerous benefits, these materials are complex and heterogenous in nature and have certain issues as well. Residual stress is one of these problems because two or more heterogeneous materials are present in a composite. This stress leads to deformation, fracture of the matrix, delamination, reduced strength, buckling of the fibers, etc. in a composite part. In this chapter, we discussed the factors that induce residual stress in composite material parts and its related issues. Methods for evaluation and simulation of residual stress in such materials are also discussed briefly.

Natural fiber-reinforced composites are the continuously growing class of sustainable materials for automotive, sports, construction and aerospace applications owing to their low weight, biodegradability, ease of availability and economic nature. However, fillers are mainly incorporated in natural fiber-reinforced composites to accelerate the performance characteristics of composites. The chapter describes the fillers (natural and synthetic), filler incorporation and composite fabrication techniques and the effect of fillers on performance characteristics such as tensile, flexural and impact. Finally, the application areas of filler reinforced composites are also highlighted.

Efforts have been made to develop biodegradable and environment-friendly materials due to environmental issues and increased dependency on fossil fuels. The usage of natural materials in composites has increased, resulting in lower greenhouse gas emissions and a lower carbon footprint for composites. Green composites have the potential to be a viable replacement for petroleum-based materials. However, it cannot be accomplished without addressing a number of concerns, including but not limited to the adhesion of the matrix with the natural fibers, reduced fire resistance, hydrophilic nature, less impact strength, durability, etc. Researchers have explored the performance of the composites reinforced with natural fibers in terms of different characterizations like physical testing (Surface morphology, thermal testing, moisture absorption, etc.), mechanical testing (tensile, compression, flexural, impact, hardness, etc.), and nondestructive testing (ultrasonic, radiography, etc.). This chapter includes the standard test methods used for these tests and the properties of natural fiber composites obtained after testing.

The fiber metal laminates (FML) combine the properties of metal and composites. The new material shows better mechanical properties as compared to constituents. As the two different types of materials are joined together so the joining of metal and composites become very crucial. The quality of the adhesive bond determines the final mechanical properties of fiber metal laminate. Most of the time aluminum is used as a metal part. Different types of surface treatments have effect on the mechanical properties and different techniques are used to evaluate the quality of different surface treatments. This chapter covers all the details related to natural fiber metal laminates including fibers, metals, surface treatment of metals, fabrication techniques, methods to evaluate metal-composite bond, and mechanical characterization of natural fiber metal laminates. The reinforcement material for the composite is synthetic fiber but the natural fibers-based fiber metal laminates are also gaining popularity due to environmental issues. This chapter presents the detailed literature on different natural fibers used for FMLs fabrication. The FMLs made with both thermoplastic and thermoset matrix along with manufacturing techniques are also presented in this chapter. This chapter also presents a comprehensive literature review of the static and dynamic properties of natural fiber reinforced thermosets and thermoplastic fiber metal laminates.