Michael Collard, age 13, of West Warwick, Rhode Island, for his question:
How is plastic made?
For several decades we pointed to man made plastics as supreme triumphs of our technology. Then we beheld the messy state of our polluted planet. We took a closer look at what becomes of our proud plastics. We saw last month's drinking cups littering our roadsides, last year's plastic bottles bobbing on our streams. Obviously it is time to find suitable methods to dispose of them. And to do so it helps to understand why these man made substances are so persistent.
Most discarded objects of wood, metal, paper and other natural substances are reclaimed by the earth. Eventually, they are broken down and recycled as new raw materials, usually to enrich the soil. But our modern plastics are made of durable man made synthetics, not found in nature. Nobody knows how long it takes the earth to decompose a polyethylene wrapper or a tough plastic container. These nondegradeable synthetics are almost impossible to recycle into the environment.
Their basic ingredients are hydrocarbon chemicals extracted from coal, petroleum and natural gas. These raw materials are cheap and plentiful but costly equipment and enormous power are used to process them into plastics. Busy researchers add to the cost, as they test methods to break apart nature's small molecules and synthesize them into large, complex man made molecules called polymers.
Manufacturers naturally strive to keep their trade secrets, hence the fine details of this or that recipe are not known. However, we do know that the major raw materials are the small gaseous molecules of benzene and methane, ethylene, propylene and butylene. Various chemical processes, heat and sometimes pressure are used to synthesize them into ringed, branched, chained or other giant polymers.
For example, different methods remodel benzene to create nylon or aspirin, dyes or detergents, polystyrene or tough synthetic rubber. Other processes synthesize methane and other small molecules into polymers of acrylic, plexiglass or antifreeze. Many of these and other man made plastics give better service than some of the natural substances they replace.
Certainly we depend on them and would feel quite lost without them. But these modern materials need modern methods of disposal, for their man made polymers are degradeable than natural substances. Otherwise the earth soon will be knee. deep in our discarded plastics.
This problem, of course, concerns the ecologists. Some suspect that all man made substances not found in nature create problems. They suggest that those researchers have not finished their work until they find ways to degrade the polymers they create. Until they do, it's up to us to clean up the clutter and find our own ways to dispose of our discarded plastics.