Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Animal Fibers

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All animal fibers are complex proteins. They are resistant to most organic acids (see Acids and Bases) and to certain powerful mineral acids such as sulfuric acid. However, protein fibers are damaged by mild alkalies (basic substances) and may be dissolved by strong alkalies such as sodium hydroxide. They can also be damaged by chlorine-based bleaches, and undiluted liquid hypochloride bleach will dissolve wool or silk.

The principal component of silk is the protein fibroin. Silk is exuded in continuous filaments from the abdomens of various insects and spiders. It is the only natural filament that commonly reaches a length of more than 1000 m (more than 3300 ft). The only silk used in commercial textiles is produced from the cocoons of the silkworm. Several silk filaments can be gathered to produce textile yarn. However, silk is often produced and used in staple form to manufacture spun yarns.

The principal component of hair, wool, and fur is the protein keratin. Individual hairs may be as long as 91 cm (36 in) but are usually no more than 41 cm (16 in). Thus, fibers of hair and wool are not continuous and must be spun into yarn if they are to be woven or knitted into textile fabrics, or they must be made into felt. Any hair fiber can legally be marketed as wool or bear the common English name of the animal from which it was gathered—for example, camel's hair.

The principal hair fiber used to produce textile fabrics is sheep's wool. In wild sheep, the wool is a short, soft underlayer protected by longer, coarser hair. In domesticated sheep bred for their fleece, the wool is much longer. Yarns made of wool are classified as either woolen or worsted. Wool fibers less than 5 cm (less than 2 in) in length are made into fuzzy, soft woolen yarns. Longer fibers are used for the smoother and firmer worsted yarns. Naturally crimped wool fibers produce air-trapping yarns that are used for insulating materials.

Other animals used as sources of hair fibers for textiles include camels, llamas, alpacas, guanacos, vicuñas, rabbits, reindeer, Angora goats, and Kashmīr (or cashmere) goats. Fur fibers from animals such as mink and beavers are sometimes blended with other hairs to spin luxury yarns but are most often found as fur pelts. Horsehair and cow's hair are used for felts and are sometimes spun as yarn, particularly for upholstery and other applications for which durability is important. Even human hair has been spun into yarn and used for textiles.