**1. Introduction**

The significance of natural fibers to fulfill the basic human needs of clothing and shelter has been well established since time immemorial. However, with the advent of synthetic fibers in 1900s, the popularity and usage of natural fibers became archaic. Nevertheless, the world wide clamor for sustainable and ecofriendly approaches in textile supply chain and depletion of petroleum resources have stimulated the usage of natural fibers thereby replacing synthetic fibers with sustainable natural fibers.

Natural fibers are grown naturally and do not pose any detrimental environmental impact except for situations where fertilizers, pesticide and other toxic chemicals are extensively utilized to improve their yield. The adverse impacts of synthetic fibers on environment and their fossil fuel based origin fosters industrial establishments, researchers and technologists to explore latest and innovative methods of growth, development, cultivation and usage of natural fibers via eco-friendly mode. Cotton holds lion's share of market as far as textile applications are concerned but the fiber cannot be considered sustainable owing to massive utilization of water, pesticides, fertilizers and toxic chemicals thereby leading to environmental and economic distress. Apart from cotton, some resource efficient fibers that are replacing cotton in varied textile applications include linen, hemp, flax, jute and bamboo.

Linen is gaining interest among textile designers for designing clothing, footwear and handbags. Hemp and jute are rope like fibers and exhibit coarseness compared to linen and generally preferred for apparels and accessories that demand rough texture and durability. Jute is a plant based multicellular fiber characterized by nodes and cross markings in longitudinal view and polygon shapes in cross-section. *Flax* is cellulosic fiber in crystalline form featuring a length of 90 cm and diameter of 12–16 μm. Flax is mainly cultivated in Canada, Netherlands, Belgium and France. The stem of plant *Linum usitatissimum* is the fiber source. The fiber extraction is accomplished by two processes namely retting and scorching to alter the fiber properties. The enzymatic application during retting process causes pectin degradation thereby resulting in separation of fibers. Flax fiber is extensively used for production of linen besides being used in furniture, home textiles and interior decor items.

Bamboo and straw are another plant based fibers gaining popularity among fashion designers. Bamboo is wood like tropical grass while the sources for straw are wheat stalks, grasses, sisal hemp and rice paper.

The extensive utilization of natural fibers for a range of textile applications is attributed to their exceptionally brilliant mechanical and physical properties like good specific modulus, low density, toughness properties, low cost, recyclability and nontoxicity. Apart from textile and fashion industry, the natural fibers find application in various industries such as automotive, building, furniture and fiber reinforced composite products [1]. A myriad of natural fibers like jute, hemp, kenaf, ramie, flax, sisal, bamboo, coir, oil palm, etc. are used for development of polymer composites on account of their biodegradability, high performance profile, sustainable attributes, lightweight and economic viability.

Furthermore, low weight, better crash absorbance and sound insulation properties of natural fibers make them ideal choice for automotive and aerospace sectors. However, the applications of natural fibers are restricted to interior structures owing to their hydrophilic nature thereby demanding chemical treatment for improving their moisture related properties. The inherent property of moisture absorption on exposure to different temperatures and humidity conditions by natural fibers presents a key challenge for their usage in different environmental conditions [2–4].

Natural fiber composites are composite materials comprising reinforcing fibers derived from renewable and carbon dioxide neutral resources like wood or plants. NFCs find application in molded articles that demand moderate strength for acceptable performance like large diameter piping, equipment housings, roofing for economical or low-budgeted housing. A rapid drift from oil derived polymers and

### *Natural Fibers: The Sustainable Alternatives for Textile and Non-Textile Applications DOI: http://dx.doi.org/10.5772/intechopen.106393*

mineral reinforced materials to sustainable alternatives has fostered automotive and packaging industries to start utilizing natural fiber composites in their designs. Accordingly, natural fiber composites are serving as an energy efficient and sustainable alternatives replacing traditional materials such as metals, polymeric resins and reinforcement fibers. A worldwide clamor for green products and thus upsurge in sustainable alternatives has been witnessed as a result of diminishing petroleum reserves worldwide, exorbitant prices of petroleum and high disposal costs of petroleumbased composites along with inability of decomposition of some petroleum based composites. Contrastingly, natural materials outshine the petroleum based products in being renewable, inexpensive, biodegradable and eco- friendly.

The demerits associated with glass fibers have prompted the emergence and wide spread acceptance of natural fibers for making composites to be suitable in automotive, furniture, packaging and building industries. Although natural fiber composites offer innumerous advantages such as lower cost, lightweight composites, biodegradability and renewable sources, however disadvantages associated with natural fibers like variations in fiber geometry and physical properties, lower mechanical properties, poor interfacial adhesion and incompatibility with hydrophobic matrix resin systems cannot be undermined.

The challenges ahead in design and manufacturing of natural fiber reinforced composites for varied applications lie in overcoming the aforesaid demerits associated with natural fiber composites.

The next section of the chapter shall discuss the fiber properties suitable for textile applications and the broad fiber classification.
