At the end of a laboratory experiment some time ago a chemist found himself left with a compound which he simply could not get out of the glass container. The steel stirring rod that had been used to mix it was firmly stuck in the center, and could not be budged. At last the scientist gave up and smashed the glass container. The lump of plastic with the steel stirring rod sticking out of it looked like a hammer, so he idly began to use it as one. To his amazement he discovered that this "hammer" was unbreakable no matter how hard he hit with it.

Samples of this material were then produced. A laboratory technician picked one up and threw it onto the floor with all his might. Nothing happened. He hurled it against the wall, and it landed with a satisfying crash.

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Then he took a hammer and went to work on it. After awhile, he admitted defeat. He could not even dent the sample.

This plastic was the first of a new group of synthetic materials. Discovered only recently, it is already beginning to replace metals in some of their traditional uses. The boundaries of the artificial world around you are expanding to include metals, in addition to fibers, food, smells and flavors. A new age is dawning -the age of plastics.

Plastic automobiles, airplanes, space ships, tractors and skyscrapers may yet become commonplace. They would look a little different from the iron, steel and aluminum we are used to today. After all, who has ever seen a transparent metal? Or a purple one? The new synthetics can be either transparent or opaque, which is the opposite, and they can be any color you have ever seen. Whatever they look like, they will do what metals can.

Many people find this hard to believe. "But plastic is so breakable" is the most common complaint. Four-year-old Johnny barely touched big brother's plastic airplane, and the wing broke off. He walked into the playroom and stumbled onto the plastic gun. You hardly need to look at it to know the bad news. But what can you expect of plastic? If you want something strong, you need to get metal.

This way of thinking could soon go out of style. By the time you are buying toys for your children you may be saying: "Let's get something that will last. Let's get plastic."

Careful experiments with samples of the new synthetic bore out the results of the early catch-as-catch-can. games. The scientists took a steel ball and dropped it from a height onto a shelf made out of the plastic. Nothing happened. They tried it again and yet again. After ten tries the shelf was still unmarked. Then they tried loading the shelf with heavy weights. It supported these with ease. In another experiment a bullet was fired at the sheet of plastic. It did not splinter.

This synthetic is a new member of an old plastics family, known as "thermoplastic resin." This means that it is a solid substance which becomes soft when heated and hard when cooled, in much the same way that metals do.

The new strong resins which can compete with metals were developed in the late 1950's and made their commercial debut in 1960. They are the end result of a long line of research that can be traced all the way back to Russia in the days of the czars. In 1859, a university professor named Alexander Butlerov began to experiment with the chemical, formaldehyde. You are probably familiar with formaldehyde. It is commonly used to preserve specimens in hospitals and zoology laboratories. Butlerov and the scientists who followed him had quite a different plan for the chemical. Their aim was to change it into a strong, solid mass. In the late 1940's, E. I. du Pont de Nemours & Company set its chemists to work. Twelve years later and $50 million poorer, the company announced success.

What the scientists did was to change the basic chemistry of formaldehyde. You have surely read about atomic energy, and know that all matter is made up of atoms. Two or more atoms form a molecule. The formaldehyde molecule consists of one carbon, one oxygen and two hydrogen atoms arranged in this pattern:

The chemists forced these molecules to become linked together in a long chain, containing more than 1,000 single molecules, like this:

This chain, which is really a giant molecule, is called a "polymer," and the process of making it is called "polymerization." These chains of molecules form an extremely strong, solid mass, different from other plastics.

"You might describe this as the `missing link' between plastics and metals," comments a chemist.

The thermoplastics made out of formaldehyde are technically described as "acetal" or "polyformaldehyde resins." You are more likely to get to know them by their trade names. Du Pont calls its resin, "Delrin," and the Celanese Corporation of America, which makes a similar product, calls it "Celcon."

Oddly enough, scientists traveling another research road arrived at the same destination. They made metal substitutes out of completely different chemicals. A chemist in the laboratories of the General Electric Company one day happened to notice a flask of a compound called "bisphenol A" on the shelf. It occurred to him that combining it with the gas "phosgene" might bring an interesting result. It did: a long, strong chain of molecules. Not quite able to believe that he had made an important discovery so easily, the researcher tried the experiment again and again, using more than 100 other compounds. None of them worked as well.

This second type of thermoplastic resin is known to scientists as "polycarbonate resin." The General Electric Company's "Lexan," and the Mobay Chemical Company's "Merlon" belong to this group.

"The new plastics act so much like metals that sheets, bars and rods made out of them can be handled on standard machine-shop equipment," explains an engineer.

These synthetics are gradually entering the fields where metal has been king.

As its name implies, hardware must be hard. Until just recently this meant it was made of metal. Nowadays not only your door knob or appliance handle can be made of plastic, but even the door hinge and the light switch have escaped from the domination of copper, brass and steel.

Everybody knows that the conveyor belts used in factories run noisily on steel ball bearings. That has always been true. Now, sometimes it is, but sometimes it is not. If you have a chance to visit a modern factory try to listen before you look. Should you happen to notice that a machine or conveyor is working particularly silently, chances are that the steel ball bearings are gone. In their place are rings made of plastic. Another possible explanation for the surprising degree of quiet in some up-to-date canneries and bottling plants is that the steel balls are enclosed in a ring of plastic. A number of equipment designers have gone yet a step further. They are using the new resins to replace steel in the actual links of the conveyor belts or chains. As most of these plastics are slippery, it is not even necessary to oil them. While no one suggests that you can hear a pin drop in the most modern factory, at least you do not need to shout in order to be heard above the din made by the machinery.

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Since the first Model T Ford came off the assembly Line, steel and other metals have had control over the automobile. Synthetics took a back seat, being used in upholstery and things of that type. The makers of the new plastics were not satisfied to leave it at that. They pointed out that these materials could go down the same old assembly line. The resins were treated to what an engineer describes as "torture testing," to see if they could be used in the actual mechanism of the car. The plastic gearshift of a speedometer was forced to run for 100,000 miles at a speed of 110 miles per hour. At the end of that time it was still fresh and ready for more.

"In its first 12 months of use Delrin replaced metals in 44 different places in an automobile," spokesmen for du Pont report proudly. "In the second year, the figure climbed to 80."

The instrument panel on a number of new cars, for example, is now made of Delrin, instead of zinc. In metal, the panel weighs 9 pounds; in plastic, only 2.

The hot Texas sun beating down on the instrument panel will not affect it, nor will the cold temperatures of Alaska. These plastics do not become brittle, even when the mercury in the thermometer drops to 40' below zero, Fahrenheit. On the other hand, they are quite indifferent to temperatures of 180° F. and can stand a blistering 250° F. if it does not continue too long. There is even one form of the new synthetic which does not get out of shape until the heat reaches 280° to 290° F.

This quality proved very useful when a worker melting metal with a soldering iron proved to be all thumbs. He dropped the white-hot iron. In his confusion he stepped on it. Luckily, his foot landed on the handle. His foot was not burned, and what is more, the handle was not broken. As you have probably guessed, the handle was made of Lexan.

It is very hard to set any of these plastics on fire. In one experiment a sample of Merlon was put into an electric furnace. The heat was raised to 400° F., then to 700°F', then to 800°F. It was not until the temperature reached a staggering 1058°F. that the material burst into flame. As soon as the heat was withdrawn, however, the fire went out. There are not many products - either natural or artificial - that could do as well.

Scientists seem determined to turn everything upside down. They are making unnatural or synthetic products that are able to withstand the forces of nature better than the natural ones can.

Farmers often complain that the cast-iron parts of agricultural machinery get rusty and worn as a result of rain, sleet, snow, sunshine and wind. They become caked with dirt quickly, too. Plastic, on the other hand, is so slippery that the dirt slithers off it.

"And who ever heard of a rusty plastic?" asks a farmer cheerfully.

What is more, even insects, rats and mice want to have nothing to do with these synthetics and leave them strictly alone.

The same is true of water. That is hardly a new idea. We take it for granted that plastics are waterproof. It is, after all, a plastic finish that makes your raincoat keep you dry. Now the users of the metal-like synthetics are taking some of these well-known properties and giving them a brand-new twist.

"Wouldn't this waterproof quality be handy on a pump that has to be submerged in water?" suggests an engineer brightly.

Just because pumping units are usually made of brass does not mean that they always need to be. A plastic pump was produced and plunged beneath the water. It ran for 1,800 hours without a break and showed no signs of wear. In another test the pump worked continuously for one year at a temperature of 140°F. This is about the amount of use a pump would normally get in nearly twenty years. At the end of the test the machine was still in excellent condition. It is not surprising that you can now find the plastic on rugged marine bilge pumps.

Even the fish in our streams and rivers are in greater danger since the new plastic was discovered. It can replace the aluminum usually used for the reel and frame of a fishing pole, and make them completely salt-waterproof. In its first year 500 industrial uses for Delrin were found, according to du Pont. More than 400 of these were as replacements for metals. Which ones? In 130 cases the plastic took the place of iron and steel; in 80 it served as a substitute for aluminum; in 60 for zinc, and in 60 for brass. And this is only the beginning of the age of plastics. The new synthetics will in time become essential to mankind. Industry eats metals greedily. Every year it takes more. The population of the world is growing at the almost unbelievable rate of one person per second. Each of these people needs goods made of metal. In addition, parts of the world which were until recently backward are developing big industries. In other words, they are becoming metals' users.

Sooner or later the earth's metal supply will become too small to fill mankind's needs. Substitutes for metal will help to provide your descendants with cars, airplanes, washing machines and television sets.

If you look far enough into the future it is even possible that metals could disappear altogether and be forgotten, except by writers of history books. Someday children might be urged to eat their spinach, in order to have muscles "as strong as plastic."

(From The artificial world around us, by Lucy Kavaler)