Man's physical universe

xanabras

678 CREATIVE CHEMISTRY

Moldings of crystal-clear transparency are used as instrument faces,

chemical-resistant bottle caps, combs, high-frequency radio parts,

buttons, and radiant, colored gems

Fig. 294. Polj'styrene lenses.

(Courtesy of Science Service.)

for costume jewelry.

In England in 1941 polystyrene

was used to produce unbreakable,

scratchproof lenses for spectacles

for the troops. These lenses were

made with the aid of eight thousand

different dies so that lenses could

be supplied for almost every conceivable

defect of vision. Each

soldier was issued two spectacles,

one for use under his respirator,

and another for ordinary use.

Pol5rv^inyl Resins Are Obtained from Salt, Coal, Lime, and Air.

A series of polyvinyl esters are manufactured by the Carbide and

Carbon Chemicals Corporation and sold under the trade-mark

"Vinylite." They may be classified as follows:

Series A — Polyvinyl acetate

Series Q — Polyvinyl chloride

Series V — Copolymer of vinyl chloride and vinyl acetate

Series X — Polyvinyl butyral

The E. I. du Pont de Nemours Company manufactures polyvinyl

butyral and sells it under the name "Butacite."

A copolymer resin of the proper chloride-acetate ratio can be produced

in the form of fibers as fine and virtually as strong as silk, but

more elastic, waterproof, and creaseproof. Such fibers are sold under

the trademark "Vinyon" and replace natural silk for many uses.

"Vinyon" fiber may be used for hosiery, gloves, bathing suits, fishing

lines, sewing threads, shower curtains, woven filter cloth, fiberbonded

felt, woven shoes, and chemical-workers' clothing. It is prepared

by polymerizing vinyl halides, such as vinyl chloride, with vinyl

esters, such as vinyl acetate.

Polyvinyl acetal resins are thermoplastic, colorless, glass-clear,

tasteless, odorless, low in density, and slow-burning. They may be

dissolved in organic solvents such as methanol, and they may be emulsified

in water. They produce durable, wear-resistant films, unaffected

by oxygen or aging. They are used for adhesives in the manufacture of

such products as drinking cups, cartons of various types, and shoes;

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