Natural Fiber-reinforced Polymer Composites

Abstract

Natural fiber composites are one of the composite materials, in which the reinforcing materials are extracted from renewable sources. Present naturally in plants and animals, plant fibers contain cellulose and lignin which produce good strength for fibers. Some of the plant-based natural fibers used as reinforcing materials include jute, hemp, oilseed, palm, kenaf, banana leaf, cotton, and flax. Animal fibers are another type of natural fibers, which largely contains proteins responsible for the strength of the fiber. Common animal fibers such as silk, hair, wool, and feathers are used as reinforcing materials. Both forms of natural fibers produce high strength when embedded in polymer matrices. Polymer matrices are used as a binding material, which combines the reinforcing materials to produce the composite material and helps distribute the load evenly throughout the composite. In general, polymer matrices like polyester, epoxy, vinyl ester, polyethylene and polypropylene are commercially available resins used as matrix materials to produce the composite material. Some of the natural resins like neem glue, plant resin, balsam, dammar gum, and amber are now used as a matrix material to bind the composite material. The advantage of using these naturally available materials is to produce an eco-friendly product for the environment and effective utilization of naturally available materials for useful purposes. Synthetic fibers are made by humans through some chemically synthesized methods. These synthetic fibers support the natural fiber to achieve the required property. Some of the synthetic fibers frequently used to synthesize a composite material are rayon, Kevlar, carbon, basalt, acrylic, zylon, spectra, and dyneema. Particulate composites are made with a combination of small particles dispersed and embedded within the matrices. This produces an additional strength for the reinforcement fiber to achieve very specific material properties. The powder form of fibers and metals are said to be particulates with the particle size of less than 200 nm. Filler materials are added to the matrix material to improve specific properties of the composite. Commercially used fillers like calcium carbonate, kaolin, talc, glass, wallostonite, and nanofillers produce some specialized composite material. The application of composites is widely used to produce a variety of products in industries such as aerospace, marine, medical, automotive parts, military, architecture, energy, infrastructure, and many others. In the era of composite materials, unique properties such as better strength-to-weight ratio than other materials make composites specifically suitable for various applications to replace metals and alloys.