Page 453 - Carrahers_Polymer_Chemistry,_Eighth_Edition

416 Carraher’s Polymer Chemistry

TABLE 12.6
Leading U.S. Glass Companies
Owen-Illinois, Inc. PPG Industries, Inc.
Corning Glass Works Owens-Corning Fiberglass Corporation
Libbery-Owens-Ford Company

ceramic materials. Both are special glasses but can contain little silica. They are typically low melt-
ing and often are not easily mixed in with more traditional glasses.
Optical fi bers can be glass fi bers that are coated with a highly refractive polymer coating such

that light entering one end of the filer is transmitted through the fiber (even around corners as

within a person’s stomach), emerging from the other end with little loss of energy. These optical

fibers can also be made to transmit sound and serve as the basis for transmission of television and
telephone signals over great distances through cables. More about optical fibers in Section 12.12.

There are many silica-intensive fibers lumped together as fi brous glass or fi berglass. A general

purpose fiberglass may contain silica (72%), calcium oxide (9.5%), MgO (3.5%), aluminum oxide
(2%), and sodium oxide (13%). The fibers are produced by melting the “glass mixture” with the mol-

ten glass drawn through an orifice. The filaments are passed through a pan containing sizing solu-

tion onto a winding drum. The take-up rate of the filament is more rapid than the exit rate from the

orifice acting to align the molecules and draw the fibers into thinner filaments. Thus, a fi ber forced

through a 0.1 cm orifice may result in filaments of 0.0005 cm diameter. This drawing increases the

strength and flexibility of the fiberglass. Applications of fiberglass include insulation and use in
composites.
Table 12.6 contains a listing of major glass-producing companies in the United States.
Optical glass for eyeglass lenses and camera lenses is typically soda-lime glass that is highly

purified so that it is highly transmissive of light. Today, there exists many other special glass that
are important in today’s society as laser glasses, photosensitive glass, photochromic windows and
eyeglass glass, invisible glasses, radiation absorbing glass, and so on. More about seeing lenses in
Section 12.8.
12.7 SAFETY GLASS
Safety glass is defi ned as “glass” that diminishes the threat of injuries and robberies as a result of
impacts, distortion, or fi re.
In 1905, British inventor John C. Wood was working with cellulose and developed a method to
adhere glass panes using celluloid as the adhesive. Wood’s version of shatter-resistant glass was
produced under the band name Triplex since it consisted of outer layers of glass with an inner layer
of celluloid polymer.
About the same time, Edouard Benedictus, a French chemist, was climbing a ladder to get
chemicals from a shelf and accidently (another discovery due to an accident) knocked a glass

fl ask onto the floor. He heard the fl ask shatter but when he looked at the broken fl ask, the broken
pieces hung together instead of breaking into many pieces and scattering over the fl oor. Benedictus

learned from his assistant that the flask had recently held a solution of cellulose nitrate. The solu-

tion of cellulose nitrate dried to give a thin film that was transparent, so the flask was set aside

as a “cleaned” flask. It was this thin film that coated the inside of the flask that held together the

broken pieces. The film was formed on evaporation of cellulose nitrate prepared from cellulose

and nitric acid.
Shortly after the laboratory accident, he read about a girl who had been badly cut from fl ying
glass resulting from an automobile accident. Later he read about other people being cut by fl ying

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