New fibers are among the many products of technology that have significantly impacted on society in the years since World War II. Nylon, rayon, orlon, dacron, polyester, and a host of other fibers have become household words because of their widespread use, primarily in textiles of all sorts.
Fibers made of glass have found wide application for home insulation and as a key component of fiberglass construction materials used in the manufacture of boats and numerous other valuable products. More recently, glass fiber is helping to transform communications as fiber-optic cables are rapidly replacing metal wires as carriers of phone messages around the world.
Now another generation of fibers is under development, whose impact may well be as great. At the University of Wisconsin-Madison, chemical engineering professor James A. Koutsky and faculty associate Stanley A. Dunn are experimenting with an approach to making stiff, high-quality fibers at a much lower unit cost than can be attained by current methods. They expect the new technique will draw upon a range of materials previously regarded as impractical for fiber-making. They also expect it to yield a variety of products, including lighter, smaller lead batteries for cars; new fiberglass composites whose superior stiffness and low cost make them the natural choice for making about bodies; fluoride optical fibers that carry crisper messages via pulses of light; and, perhaps, exotic new fibers that would make the manufacture of high-temperature superconducting wires a possibility.
Koutsky and Dunn have revived and refined a dormant technology, Inviscid Melt Spinning (IMS), that engineers have known about for decades without understanding it or realizing this potential for producing strong, thin, cost-effective wires and fibers. Although the materials industry has yet to fully recognize the value of IMS-type fibers, Koutsky and Dunn expect that IMS will soon be competitive in producing fiberglass and other fibers commonly used in certain reinforced plastics.
Conventional Fiber-Making
Long, continuous wires and fibers--collectively referred to as fibers--are now produced from heat-softened materials by a variety of commercial processes falling primarily into two classes, drawing and spinning. The choice of process is determined by the physical properties of the fiberizing material.
For the drawing process used to make metal wires of all sorts, the starting material is typically a rod half an inch in diameter that is pulled (or drawn) repeatedly through progressively smaller dies that reduce it to thin wire of a specified diameter. However, most metals, such as steel, lose ductility with repeated redrawing, and restoring their malleability requires frequent heating--perhaps 50-100 times, depending on the final diameter. This makes the process slow and costly.
Like drawn fibers, fibers produced by the conventional spinning process are also strong, thin, and continuous. The process requires a material that can be melted to a viscous liquid of consistency similar to thick honey. In making glass fibers, for example, silica, the primary component of glass, is melted to a thick consistency at temperatures hovering around its melting point. Before the silica can be fiberized, it must
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