Fibers

Fibers are slender, elongated materials with a high length-to-diameter ratio, capable of being drawn into filaments or used in bulk form. They occur naturally or are manufactured, and are used to make textiles, composites, and a range of other products.

Classification: Natural fibers include plant fibers such as cotton and flax, animal fibers such as wool and silk, and mineral fibers such as asbestos (historical; now restricted). Man-made fibers are produced from polymers and include synthetic fibers like polyester and nylon, regenerated fibers like viscose (rayon), and advanced fibers such as carbon fiber and Kevlar. Fibers can be staple (short, discrete lengths) or filament (long continuous strands).

Manufacture and properties: Natural fibers are obtained from plants or animals and undergo cleansing and, for some, retting. Synthetic fibers are formed by polymerizing monomers and extruding the molten or dissolved polymer through spinnerets (melt-spinning, dry-spinning, wet-spinning). Key properties include tenacity, modulus, elongation, stiffness, density, and moisture regain, which influence performance in textiles or composites.

Applications: Textiles and apparel represent common consumer uses; nonwovens, filters, and medical products use fibers in porous sheets or mats; in engineering, fibers reinforce composite materials to improve strength and stiffness. Fiber cement, insulation, and geotextiles are other examples.

Sustainability and health: Natural fibers are renewable but vary in cultivation impact; synthetic fibers rely on petrochemicals and raise concerns about microplastics and end-of-life disposal. Some mineral fibers pose health risks if fibers become airborne; proper handling and standards reduce hazards.