Glass Fiber

glass fiber: see fiberglass.

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glass fiber [¦glas ¦fī·bər]

(materials)

A glass thread less than a thousandth of an inch (25 micrometers) thick, used loosely or in woven form as an acoustic, electrical, or thermal insulating material and as a reinforcing material in laminated plastics. Also known as fiberglass.

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fiberglass, fibrous glass, glass fiber

Filaments of glass, formed by pulling or spinning molten glass into random lengths; either gathered in a wool-like mass or formed as continuous thread-like filaments having diameters in the range of 10 to 30 µ m. The wool-like material is processed into many forms of varying densities for use as thermal and acoustical insulation. The continuous-filament type is used for textiles, glass fabrics, and electrical insulation and as reinforcement for other materials.

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Glass Fiber 

fiber made from molten glass in the form of threads. Continuous fibers have a diameter of 3–100 micrometers and are produced in lengths of 20 km and more; staple glass fibers have a diameter of 0.1–20 micrometers and a length of 1–50 cm. In appearance, continuous fibers resemble threads of natural or synthetic silk, while staple fibers resemble short cotton or wool fibers.

Continuous glass fibers are produced in a drawing process that involves pulling fibers from molten glass through spinnerets having 200–2,000 holes and, with the aid of mechanical devices, winding the fibers on spools. The diameter of the fiber depends on the rate of the drawing and the diameter of the spinneret hole. The production process can be carried out in one or two steps. In the single-step process, the fibers are drawn from molten glass directly from the glassmaking furnace, while in the two-step process glass marbles, rods, or lumps of partially fused glass are first formed and then remelted in the furnace. Methods for producing staple glass fibers include a single-step process of dividing the streams of molten glass using steam, air, or hot gases.

The properties of glass fibers are determined mainly by the chemical composition and are characterized by the rare combination of desirable features. One feature is a marked ability to withstand thermal stress; for example, quartz, silica, and kaolin fibers can withstand stresses above 1000°C. The fibers also have good dielectrical properties; the volume resistivity of quartz, nonalka-line aluminoborosilicate, and magnesiumaluminosilicate glass fibers is 10¹⁴ ohm-cm and above. Other features include low thermal conductivity, low coefficient of thermal expansion, high chemical resistance, and high mechanical strength (3,000–5,000 meganewtons/m², or 300–500 kilograms-force/mm²). Glass fibers in the form of rovings, yarns, bands, fabrics of various weaves, and nonfabric materials are widely used in modern technology as reinforcing materials for fiber glass reinforced plastics and other laminates, as well as in the production of filter materials and electrically insulating articles in the electrical industry.

M. S. ASLANOVA