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Natural fiber‐reinforced polymer (FRP) composites or biocomposites are gaining widespread interest for many reasons. One such reason is the fact that they have shown a potential for replacement of synthetic fibers at a lower cost. They are also sustainable when compared with their synthetic counterparts [5].

Natural fibers refer to fibers whose origins are natural, that is, they are sourced from plants and animals. These origins give rise to three fundamental natural fiber types, viz:

 Animal fibers: These contain proteins, such as keratin, fibroin, and collagen. Other classifications in this category are animal wool/hairs (angora wool, alpaca, camel, mohair, lamb's wool, bison, yak wool, cashmere, horse hair, goat hair, and qiviut, among others), keratin fiber (chicken and bird feathers), and silk fibers (spider silk, tussah silkmoths, mulberry silk cocoons).

 Plant fibers: These are often referred to as cellulosic or lignocellulosic fibers. They are classified in six categories:Seed/fruit fibers: Coir, coconut, loofah, cotton, oil palm, kapok, sponge gourd, milkweed hairs.Cane, grass, and reed fibers: Bamboo, corn, albardine, esparto, bagasse, sabai, papyrus, rape, canary.Bast or stem fibers: Blax, jute, okra, rattan, paper mulberry, hemp, kenaf, isora, urena, ramie, kudzu, roselle hemp, wisteria, mesta and nettle, among others.Wood fibers: Hardwood and softwood, among others.Leaf fibers: Caraua, pineapple, abaca, raphia, agave, caroa, banana, fique, piassava, cantala, sansevieria, phormium, Mauritius hemp, sisal, date palm, istle and henequen, to mention but a few.Stalk fibers: Derivable from barley stalk, rice stalk, maize stalk, wheat stalk, oat stalk as well as other crops. Table 1.2 shows the percentage weight (wt.%) of chemical compositions of the mostly used natural fibers.

 Mineral fibers: These fibers include fibrous brucite, asbestos group (amosite, chrysotile, anthophyllite, crocidolite, actinolite and tremolite) and wollastonite.

Table 1.2 Commonly used natural fibers in hybrid composites and their chemical compositions.

Source: Faruk et al. [6]. © 2012, Elsevier.

Fiber	Cellulose (wt.%)	Hemicellulose (wt.%)	Lignin (wt.%)	Waxes (wt.%)
Abaca	56–63	20–25	7–9	3
Bagasse	55.2	16.8	25.3	—
Bamboo	26–43	30	21–31	—
Coir	32–43	0.15–0.25	40–45	—
Curaua	73.6	9.9	7.5	—
Flax	71	18.6–20.6	2.2	1.5
Hemp	68	15	10	0.8
Jute	61–71	14–20	12–13	0.5
Kenaf	72	20.3	9	—
Oil palm	65	—	29	—
Pineapple	81	—	12.7	—
Ramie	68.6–76.2	13–16	0.6–0.7	0.3
Rice husk	35–45	19–25	20	14–17
Rice straw	41–57	33	8–19	8–38
Sisal	65	12	9.9	2
Wheat straw	38–45	15–31	12–20	—