Mitchell Constantino age 10, of Spring Valley, Calif., for his question:
FROM WHAT IS PLASTIC MADE?
Elephants were becoming scarce in the middle of the last century and a billiard ball maker, realizing that ivory would soon not be available, offered a $10,000 award for a good substitute. An American printer named John Wesley Hyatt and his brother Isaiah didn't win the prize but they started a vast, new industry when they came up with a plastic mass that could be molded. They used a cellulose of cotton softened with nitric acid and aded camphor. The result, patented in 1869, was named Celluloid.
Celluloid, our first commercial plastic material, didn't work out for billiard balls but it definitely became a substitute for the diminishing supply of ivory in the late 1800s. It worked well for combs, buttons, fountain pens, piano keys and frames for glasses.
The word "plastic" is a family name just as the word "metal" is a family name.` There are many different types of metals and many different types of plastics.
Some plastics are made from cotton, wood or other plant cellulose. Cellulose is the fiber that makes up the cell walls of plants. Other plastics are made from natural resins such as rosin, asphalt and pitch. Still other plastics are made from synthetic resins created by chemists from cheap and abundant raw materials such as air, petroleum, coal and castor oil. Proteins found in soybeans and milk offer the source for still another type of plastics.
Plastics fall into two groups: (1) thermosetting plastics which are those hardened or set into permanent shapes when heat and pressure are applied (once hardened, they cannot be made soft again) and (2) thermoplastics, the type that can be softened by heat.
Plastics are so important these days that it is hard to imagine life without them. They are used, for example, in making safety film for movies, safety glass, costume jewelry, tool handles, protective goggles and even eyeglasses. You'll also find plastic in phonograph records and thousands of other products we come into contact with daily.
During World War II when there was a scarcity of silk, rubber and metal, the plastics industry expanded tremendously in a wide variety of areas. One of the most important plastics developed at this time (a synthetic resin thermoplastic) was vinyl. It makes life easier for us in hundreds of ways. Vinyl is used for unbreakable phonograph records, floor coverings, adhesives, paper and cloth coatings, gloves, wire and cable insulations and liners used for tanks that hold acid. Its fibers are woven into draperies and furniture covers, and it provides that natural feeling skin of dolls.
Another plastic is acrylic. It's used for watch crystals and camera lenses as well as for display signs and lighting fixtures.
Polystyrene is probably the best known of the synthetic thermoplastics. Almost all plastic toys are made of polystyrene, and it is also used for tableware and kitchen appliances. It is used in making washable water paints, too.