Man's physical universe



Fig. 297. A tongue depressor made

of curved "Lucite" methyl methacrylate

plastic. (Courtesy of the

E. I. du Pont de Nemours Company.)

with minimum distortion and are

thus used in transmitting speech

through flexible conduits.

Polyvinyl alcohols are used in

photolithographing printing. A

solution of polyvinyl alcohols, sensitized

to light by adding ammonium

or potassium dichromate, is

coated on a zinc plate.

This plate

is then "exposed" like other photographic

plates and developed by

simply washing in water. The nonexposed

portions are soluble in

water, while the exposed portions

are rendered insoluble by the action

of the light and remain on the plate

to form the printing surface.

Polyvinyl alcohols may be used

as an emulsifier in making such cosmetic products as cold creams,

brushless shaving creams, cleansing creams, and beard-setting preparations

for use with electric razors. They also increase the sticking

and spreading power of insecticide sprays and, when coated on glass,

make it nonfogging under conditions of high humidity inside and low

temperatures outside of a room.

" Super-glass " Is Now Made from

Polymethyl Methacrylate.

A few years ago one of the felt

needs was an organic "glass." Today

we have in polymethyl methacrylate

a product clearer than

optical glass, weighing half as much,

which may be cut, turned, sawed,

carved, drilled, polished, shaped,

formed, and swaged. It is flexible,

durable, and strong, and may be

given translucent, opaque, or pearl

color effects. This product, sold under

the names of "Lucite" methyl

methacrylate plastic,


or "Crystalite," is derived ultimately

from air, water, and coal or

Fig. 298. Printed material shown

through a 93^2 inch thickness of

"Lucite" meth}! methacrylate plastic.

(Courtesy of the E. I. du Pont de

Nemours Company.)

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