Plastics - What Are They?

In the 1967 movie, The Graduate, a confused and somewhat depressed young college graduate named Ben, played by Dustin Hoffman, received some famous advice from a friend of his parents:

Mr. McGuire: I just want to say one word to you just one word.
Ben: Yes sir.
Mr. McGuire: Are you listening?
Ben: Yes I am.
Mr. McGuire: 'Plastics.'
Ben: Exactly how do you mean?
Mr. McGuire: There's a great future in plastics. Think about it. Will you think about it?
Ben: Yes I will.
Mr. McGuire: Shh! Enough said. That's a deal.

The intervening years have proven that Mr. McGuire did indeed have a hot tip, even if Ben was not very interested at the time. Like it or not, plastics have become a dominant industrial material.

Plastic overtook steel in volumes manufactured in 1979, and the trend continues. In western countries, we use (and throw away) a wide array of film, fabric and moulded plastics every day.

What exactly are plastics, anyway? The word comes from the Greek plastikos, meaning "fit for moulding". The materials we call plastics are heat treated polymers. A polymer is a giant molecule formed by joining simple molecules (monomers) together like beads on a string. There are two basic types:

1. thermoplastic polymers which can be reheated and formed over and over
2. thermoset polymers which cannot be remelted

Plastics, regardless of type, share some general attributes:

• resistance to breakdown by other chemicals or micro organisms
• act as both thermal and electrical insulators
• lightweight, with varying degrees of strength
• can be processed to make a wide range of shapes, including fibres

The first man-made plastics, introduced in the latter part of the 19th century, were made from naturally occurring polymers like cellulose and rubber. Plastic started to become a more commonly used type of material with the development of Bakelite, the first synthetic polymer, by Leo Baekeland in 1907. Cellophane was created in 1913, followed by PVC in 1926, polyethylene in 1933, Saran in 1933, Teflon in 1938, nylon in 1939 and velcro in 1957. Interestingly, many of the discoveries were made when experiments went wrong, or were gleaned from observations made in other tests. World War II was the proving ground for many plastic products. (For more history see the American Chemistry Council website.)

(Source: WasteWatch, September 2002)

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