A Plastics Explosion - Polyethylene, Polypropylene, and Others

Other plastics emerged in the prewar period, though some wouldn't come into widespread use until after the war.

By 1936, American, British, and German companies were producing "polymethyl methacrylate" (PMMA), better known as "acrylic."  Although acrylics are now well-known for the use in paints and synthetic fibers, such as "fake furs," in their bulk form they are actually very hard and more transparent than glass, and are sold as glass replacements under trade names such as "plexiglas" and "lucite."  Plexiglas was used to build aircraft canopies during the war, and it is also now used as a marble replacement for countertops.

Another important plastic, polyethylene (sometimes known as "polythene") was discovered in 1933 by Reginald Gibson and Eric Fawcett at the British industrial giant Imperial Chemical Industries (ICI).  This material evolved into two forms, low density polyethylene (LDPE) and high density polyethylene (HDPE).

Polyethylene is cheap, flexible, durable, and chemically resistant.  LDPE is used to make films and packaging materials, including plastic bags, while HDPE is used more often to make containers, plumbing, and automotive fittings.  While PE has low resistance to chemical attack, it was found later that a PE container could be made much more robust by exposing it to fluorine gas, which modified the surface layer of the container into the much tougher "polyfluoroethylene."

Polyethylene would lead, after the war, to another material, "polypropylene" (PP), which was discovered in the early 1950s.  It is common in modern science and technology that the growth of the general body of knowledge can lead to the same inventions in different places at about the same time, but polypropylene was an extreme case of this phenomenon, being separately invented about nine times.  It was a patent attorney's dream scenario, and litigation wasn't resolved until 1989.

Polypropylene managed to survive the legal process, and two American chemists working for Phillips Petroleum of the Netherlands, Paul Hogan and Robert Banks, are now generally credited as the "official" inventors of the material.  Polypropylene is similar to its ancestor, polyethylene, and shares polyethylene's low cost, but it is much more robust.  It is used in everything from plastic bottles to carpets to plastic furniture, and is very heavily used in automobiles.

Polyurethane was invented by Friedrich Bayer & Company of Germany in 1937.  It would come into use, after the war, in blown form for mattresses, furniture padding, and thermal insulation.  It is also used in non-blown form for sports wear such as "lycra."

In 1939, I.G. Farben Industrie of Germany filed a patent for "polyepoxide" or "epoxy."  Epoxies are a class of thermoset plastics that form cross-links and "cure" when a catalyzing agent, or "hardener," is added.  After the war, they would come into wide use for coatings, "super glues," and composite materials.

Composites using epoxy as a matrix include "fiberglass," where the structural element is glass fiber, and "carbon-epoxy composites," in which the structural element is carbon fiber.  Fiberglass is now often used to build sport boats, and carbon-epoxy composites are an increasingly important structural element in aircraft, as they are lightweight, strong, and heat-resistant.

Two chemists named Rex Whinfield and James Dickson, working at a small English company with the quaint name of the "Calico Printer's Association" in Manchester, developed "polyethylene terephthalate" (PET or PETE) in 1941.  It would be used for synthetic fibers in the postwar era, with names such as "polyester," "dacron," and "terylene."

PET is more impermeable than other low-cost plastics and so is a popular material for making bottles for Coke and other "fizzy drinks," since carbonation tends to attack other plastics, and for acidic drinks such as fruit or vegetable juices.  PET is also strong and abrasion resistant, and is used for making mechanical parts, food trays, and other items that have to endure abuse. PET films, trade-named "mylar," are used to make recording tape.

One of the most impressive plastics used in the war, and a top secret, was "polytetrafluoroethylene" (PTFE), better known as "teflon," which could be deposited on metal surfaces as a scratchproof and corrosion-resistant, low-friction protective coating.  The polyfluoroethylene surface layer created by exposing a polyethylene container to fluorine gas is very similar to teflon.

A Du Pont chemist name Roy Plunkett discovered teflon by accident in 1938.  During the war, it was used in gaseous-diffusion processes to refine uranium for the atomic bomb, as the process was highly corrosive.  By the early 1960s, teflon "non-stick" frying pans were a hot consumer item.

Teflon was later used to synthesize the miracle fabric "GoreTex," which can be used to build raingear that in principle "breathes" to keep the wearer's moisture from building up.  GoreTex is also used for surgical implants; teflon strand is used to make dental floss; and teflon mixed with fluorine compounds is used to make "decoy" flares dropped by aircraft to distract heat-seeking missiles.

After the war, the new plastics that had been developed entered the consumer mainstream in a flood.  New manufacturing was developed, using various forming, molding, casting, and extrusion processes, to churn out plastic products in vast quantities.  American consumers enthusiastically adopted the endless range of colorful, cheap, and durable plastic gimmicks being produced for new suburban home life.

One of the most visible parts of this plastics invasion was Earl Tupper's "tupperware," a complete line of sealable polyethylene food containers that Tupper cleverly promoted through a network of housewives who sold Tupperware as a means of bringing in some money.  The Tupperware line of products was well thought out and highly effective, greatly reducing spoilage of foods in storage.  Thin-film "plastic wrap" that could be purchased in rolls also helped keep food fresh.

Another prominent element in 1950s homes was "formica," a plastic laminate that was used to surface furniture and cabinetry.  Formica was durable and attractive.  It was particularly useful in kitchens, as it did not absorb, and could be easily cleaned of stains from food preparation, such as blood or grease.  With formica, a very attractive and well-built table could be built using low-cost and lightweight plywood with formica covering, rather than expensive and heavy hardwoods like oak or mahogany.

Composite materials like fiberglass came into use for building boats and, in some cases, cars.  Polyurethane foam was used to fill mattresses, and styrofoam was used to line ice coolers and make float toys.

Plastics continue to be improved.  General Electric introduced "lexan," a high-impact "polycarbonate" plastic, in the 1970s.  Du Pont developed "kevlar," an extremely strong synthetic fiber that was best-known for its use in bullet-proof vests and combat helmets.  Kevlar was so remarkable that Du Pont officials actually had to release statements to deny rumors that the company had received the recipe for it from space aliens.

One of the most potentially important new developments in plastics is circuits made out of plastics called conductive polymers.  Electronic circuitry fabricated using plastics or other materials that could be simply printed on a substrate could be incredibly cheap, opening the door to throwaway electronic devices that would cost pennies, or to applications hardly dreamed of now.

So far, electronic devices made with such materials have not been acceptable for production but, in 2001, prototypes of flat-panel displays based on such technologies were being publicly demonstrated, with predictions of commercial introduction in two or three years.

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