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Facts of the Matter Richard Brill |
Plastic is fantastic
but has drawbacksThe material is found in
a wide range of uses but also
can harm the environmentIn the 1967 film, "The Graduate," young Benjamin Braddock Hoffman is given hushed advice by his father's friend: "Plastics." Screenwriters Calder Willingham and Buck Henry even then recognized that the synthetic material made from petroleum had only begun to reach its potential as the most versatile man-made material.
The word comes from the Greek, plastikos, meaning to mold or to form, so named because of the low working temperature and the ease at which it can be injected into molds. Compared to glass, which becomes "plastic" enough to flow sufficiently into molds at 2,200 degrees Fahrenheit, plastics can be molded from 400 to 600 degrees, depending on the type.
All plastics are varieties of a class of chemical compounds called polymers, literally "many parts" (from Greek poly [many] + meros [part]). A polymer is a substance that consists of structural units of molecules that are linked together in chains or networks.
Although we associate plastics with modern times, the first plastic material, polystyrene, was discovered accidentally in 1839 by a German apothecary, Eduard Simon. He isolated it from natural resin but he did not know that what he had discovered was a plastic polymer.
It was not until 1922 that organic chemist Hermann Staudinger realized that Simon's discovery consisted of long chains of styrene molecules. Coining the word "polymer," he wrote that the materials manufactured by the thermal processing of styrene were similar to rubber, made up of long repetitive chains of monomers that gave rubber its elasticity. Staudinger won the 1953 Nobel Prize for Chemistry for his polymer research.
SOME HISTORIANS believe the plastics industry began in 1868 when young American printer, John Wesley Hyatt won a $10,000 prize for inventing a new material to be used as a substitute for ivory in billiard balls.
Hyatt found that cellulose nitrate -- formed by the action of nitric acid on cotton cellulose, mixed with camphor and treated with proper amounts of pressure and heat -- produced a substance that could be molded into desired shapes. He called his new material celluloid. It not only became the material used for movie film, but also may have saved elephants from extinction by removing the demand for ivory.
Others say the plastic era began in 1909, as a necessity due to the blossoming use of electricity in homes and industry. At that time, shellac was used for insulation on electrical wires and demand for shellac soon outstripped supply. A German chemist, Leo Baekeland, recognizing a killer app when he saw one, began looking for a synthetic substitute for shellac.
In 1907 Baekeland made Bakelite, considered to be the first synthetic plastic resin, by mixing carbolic acid with formaldehyde. In 1909 he introduced it to the general public at a chemical conference, and it soon became the material of choice for many applications.
PLASTICS have found application in just about everything we do and in everything we use to do them. The list includes automobile body and interior parts, electronic applications, appliance and electronic cases, shrink wrap packaging, floor covering, film, sheet, bags, profile shapes, pipes, pipe fittings, laminates, foam products, containers and bottles.
Plastic has become the first choice for packaging because it is strong and can be formed and seal with heat, although once punctured it tears easily.
Ten percent of the average grocery bill pays for packaging (more than goes to the farmers) and consumer products are packaged in thick shrink wrap, much of it to thwart shoplifters, but also for attractive displays on the shelf.
Plastics are relatively cheap to make, and can be made with a wide range of properties. Today plastic production accounts for uses 4 percent of the world's oil compared to 31 percent for transportation fuel. The use of plastics continues to increase by 5 percent or more per year, such that world production in 2004 is estimated to reach about 8 million tons. The world produces enough plastic film alone to shrink-wrap the entire state of Hawaii sixty times over.
Despite the utility and the outward appearance of being very nearly the ideal material, plastic has its shortcomings, both in applications and disposal. Because of the variety of properties among the array of different types, choosing the right plastic for an application is important.
One obvious disadvantage is the low softening temperature of some plastics. There are many varieties of plastic products that are dishwasher and microwave safe, but many that are not, and it is not always easy to tell the difference.
Plastics are chemical cousins to fats and oils, so oil and other organic solvents are corrosive to many plastics, causing them to soften. The oils in some foods stain or trap odors in plastic containers, such as the red-orange stain from that leftover spaghetti sauce.
Plastics are flammable, and become hot, viscous liquids when ablaze. Clothing, tents, and other products made from polyester and other synthetic fibers can cause serious burns if they catch fire. Many fabrics are now treated with flame retardants to reduce the risk of injury and damage from fire.
Many plastics give off volatile organic compounds (VOC), to which many people are allergic. Carpets made from synthetic polymers may emit huge amounts of VOC. That familiar and inimitable new car smell is due to the release of additives used in the many plastic parts in automobile interiors. A typical American car is nearly 10 percent plastic, amounting to 375 pounds of plastic of 60 different types.
The other downside of the plastic story is the difficulty of disposal. Incineration of plastics leads to the release of toxic fumes, unless carried out at very high temperatures. They have a long lifetime in the environment because they are not biodegradable.
Plastics weather slowly with exposure to the weak UV radiation in sunlight. As they weather at the surface they become scaly and brittle. The scales gradually disintegrate into smaller and smaller pieces, but are not broken down chemically. Underground in land fills the plastic decreases little in bulk. When disposed of carelessly, plastics can become environmental hazards of various kinds. It is not only bulk, released toxins, and aesthetics that are of concern, but also the effects on the food chain.
Microscopic plastic particles may stay suspended in seawater, and looking very much like plankton, are mistaken for food by sea turtles and birds or trapped by filter feeders such as jellyfish and baleen whales.
One study on a remote Pacific island found Laysan Albatross chicks that died of starvation or dehydration due to a accumulation of indigestible plastics in their stomachs.
The full impact of large amounts of plastic and plastic residue in the environment can not be known, but it is certain that the amounts are becoming large enough to exert environmental stress on the food chain.
Plastics are the miracle materials of our time, and a testament to our ingenuity and technological sophistication. There is no question that they have added to the quality of life, but without careful management of the garbage they produce, there could be incalculable damage to the fragile and already stressed ecosystem upon which we, as well as all living things depend.
Richard Brill picks up where your high school science teacher left off. He is a professor of science at Honolulu Community College, where he teaches earth and physical science and investigates life and the universe. He can be contacted by e-mail at rickb@hcc.hawaii.edu