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.

Nylon

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Nylon, term applied to a synthetic resin widely used for textile fibers, characterized by great strength, toughness, and elasticity, and processed also in the form of bristles and molded articles. Nylon was developed in the 1930s by scientists of Eleuthère Irénée du Pont de Nemours, headed by the American chemist Wallace Hume Carothers. It is usually made by polymerizing adipic acid and hexamethylenediamine, an amine derivative. Adipic acid is derived from phenol; hexamethylenediamine is made by treating adipic acid catalytically with ammonia and hydrogenating the product Hydrogenation. Nylon is insoluble in water and in ordinary organic solvents; it dissolves in phenol, cresol, and formic acid, and melts at 263° C (505° F).

In making textile fibers, small chips of the nylon polymer, which is obtained as a tough, ivorylike material, are melted and forced through holes in a metal disk called a spinneret. The filaments are congealed by a blast of air and are then drawn to about four times their original lengths. The diameter of the filaments is controlled by changing the rate at which the molten nylon is pumped into the spinneret and the rate at which the filaments are drawn away. Filaments much finer than those of ordinary textile fibers can be made from nylon. Nylon fibers can have the appearance and luster of silk or can be made to resemble natural fibers such as cotton; their tensile strength is higher than that of wool, silk, rayon, or cotton. Dyes are applied either to the molten mass of nylon or to the yarn or finished fabric. Acetate rayon dyes are usually used for nylon.

Nylon is used in the manufacture of fabrics for such articles as hosiery, night garments, underwear, blouses, shirts, and raincoats. Nylon fabrics are water-resistant; they dry quickly when laundered and usually require little to no ironing. Nylon fibers are also used for parachutes, insect screening, medical sutures, strings for tennis rackets, brush bristles, rope, and fishing nets and line. Molded nylon is used for insulating material, combs, dishware, and machinery parts.