More about Plastics

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Plastics comprise a wide range of products characterized by their polymer base. Polymers are long chains of specific repeating atomic structures, known as monomers. A good example of one of these monomers is CH=CH2, which is the chemical backbone of Styrofoam. Although the first plastics were invented in the nineteenth century, it was not until the twentieth century that most plastics—especially synthetics—found large scale use.

Many of today’s most widely used plastics were developed in the first half of the twentieth century. These include nylon (polyamide), polystyrene, polyethylene and Teflon, which all have extensive industrial, commercial and domestic uses. Nylon was actually the result of a lengthy experimentation process conducted by scientists working for DuPont, which was at the time looking for a material that could replace silk stockings. Today, nylon is used in fabrics, industrial machinery, small motors and many other areas.

Plastics are generally made from petroleum, which is then chemically altered and treated to certain additives and processes. However, the creation of plastics accounts for only a small percentage of the world’s fossil fuel consumption. The resulting materials have an incredibly wide variety of characteristics, from exceptional elasticity and durability to extreme brittleness. They are used in everything from food containers, clothing and electronics to medical equipment, precision aircraft devices and military hardware.

Plastic components and fibers are created by a variety of methods. Originally, molding and extrusion were used almost exclusively; while they are still widely used today, there are a number of other manufacturing techniques employed. Injection molding, one of the most popular manufacturing methods, involves forcing molten plastic into a pre-made mold. Once the part has cooled and been removed, it is subjected to various machining processes to remove excess plastic, finish the surface and/or add additional shapes. Extrusion, on the other hand, involves forcing a partially liquefied plastic through a small die opening, thereby creating a long tube with the profile of the die.