Plastic

The word plastic derives from the Greek plastikos- fit for molding and plastos- molded. Plastic is a wide range of synthetic or semisynthetic organic amorphous solid materials suitable for the industrial or commercial products. Plastics are polymers of high molecular mass, that may contain other substances to reduce costs or improve performance. Modern manufacturing processes allow them to be pressed, cast, or extruded into different kinds of shapes—such as bottles, fibers, boxes, plates, films, and much more.

There are two types of plastics:

Thermosets, that can melt and take shape once, and stay solid after they have solidified,
Thermoplastics, that will soften and melt when enough heat is applied, for example: polyvinyl chloride, polystyrene, polyethylene, and polytetrafluoroethylene (PTFE).
Plastics can be classified by the chemical process used in their synthesis; for example, as cross-linking, condensation or polyaddition.

Plastics can also be classified by their chemical structure, for example, silicone, halogenated plastics, polyesters, polyurethanes or the acrylics.

They can also be ranked by various physical properties, such as tensile strength, resistance to various chemical products, density, glass transition temperature, etc.

Other classifications are based on qualities that are relevant for manufacturing or product design, for example, electrically conductive, elastomer, biodegradable, structural, the thermoplastic and thermoset, etc.

Plastics have already displaced many traditional materials, such as paper, wood, stone, leather, metal, glass, horn and bone; and ceramic.

They are used in a huge range of products because they can easily be manufactured, they are relatively low cost and imperviousness to water and versatility.

The first man-made plastic called Parkesine (later called celluloid) was created by Alexander Parkes and was publicly demonstrated at the 1862 Great International Exhibition in London. It was an organic material derived from cellulose that once heated could be molded, and retained its shape when cooled.

Celluloid became famous as the first flexible photographic film used for still photography and motion pictures.

Bakelite was the first true plastic based on a synthetic polymer. It was cheap, strong, and durable and made from phenol and formaldehyde. Bakelite was also the first thermosetting plastic.

Polystyrene (PS) and polyvinyl chloride (PVC), developed by IG Farben of Germany were the earliest examples in the wave of new plastics after the First World War. Polystyrene (PS) is a brittle, inexpensive, rigid plastic that has been used to make plastic model kits and similar knick-knacks and would also be the basis for styrene foam or Styrofoam.

Polyvinyl chloride (PVC) is strong, heat, stiff and weather resistant, and is used for making house siding, plumbing, enclosures for computers, gutters, etc. PVC in its softened form is used for rain gear, food packaging and shrink-wrap.

Polyamide (nylon) was the first purely synthetic fiber, introduced by DuPont Corporation at the 1939 World's Fair in New York City.

Nylon in its bulk form is very wear resistant and is used to build gears, bushings, bearings and for under-the-hood applications in cars, and other mechanical parts.

Natural rubber is an elastomer that was originally derived from latex and is useful directly in this form. In 1839 Charles Goodyear invented vulcanized rubber.

Lebedev synthesized the first fully synthetic rubber in 1910.

Polymethyl methacrylate (acrylic glass) was produced by American, British and German companies by 1936.

Acrylics are now used in paints and synthetic fibers, such as fake furs. In their bulk form they are very hard and more transparent than glass, and are sold as glass replacements.

Polyethylene (polythene) is another important plastic that was discovered in 1933 by Eric Fawcett and Reginald Gibson at the British industrial giant Imperial Chemical Industries (ICI). It is flexible, durable, cheap and chemically resistant. Polyethylene (PE) evolved into two forms, low density polyethylene (LDPE) that is used to make films and packaging materials, and high density polyethylene (HDPE) used for automotive fittings, plumbing and containers.

Polypropylene (PP) was discovered in the early 1950s by Giulio Natta. It is similar to polyethylene but much more robust. Polypropylene is very heavily used in automobiles and also in plastic furniture, bottles, carpets, etc.

Polyurethane (PU) was invented by Friedrich Bayer & Company in 1937 and was used after the war in blown form for furniture padding, thermal insulation and mattresses. In non-blown form it is also one of the components of the fiber spandex.

Polyepoxide (epoxy) is a class of thermoset plastic that form cross-links and cure when a catalyzing agent, or hardener, is added. After the war they were used for composite materials, coatings and adhesives.

Polyethylene terephthalate (PET or PETE) was developed by James Dickson and Rex Whinfield in 1941. It is strong and abrasion resistant, and is used for making food trays, mechanical parts and other items. PET is less gas-permeable than other low-cost plastics and used for making bottles for Coca-Cola and other carbonated drinks.

Teflon (polytetrafluoroethylene, PTFE) is one of the most impressive plastics used in the war. It could be deposited on metal surfaces as a corrosion-resistant and scratch-proof, low-friction protective coating.

Pure plastics have low toxicity in their finished state, due to their relative chemical inertness and insolubility in water. They often contain different kinds of toxic additives, for example, phthalates and adipates are often added to brittle plastics to make them pliable enough for use in children's toys and teethers, food packaging, shower curtains, tubing, etc.

The finished plastic may be non-toxic, but the monomers used in its manufacture may be toxic and small amounts of those chemical may remain trapped in the product.

The chemical used to make PVC has been recognized by the World Health Organization's International Agency for Research on Cancer (IARC) as a known human carcinogen.

The manufacturing of plastics often creates a lot of chemical pollutants. Burning plastic can release toxic fumes, but burning PVC may create dioxin.

Thermoset plastics can be ground up and used as filler, and thermoplastics can be remelted and reused. Plastics can also be broken back down to a feedstock state.

Recycling plastics is difficult because it is hard to automate the sorting of plastic waste and it is labor intensive.

The cost of plastics has been rising dramatically in recent years because of the sharply rising cost of petroleum, the raw material that is chemically altered to form commercial plastics.

Plastic is made of oil and doesn't biodegrade, so cutting back on plastic helps preserve natural resources.