Poly... What Plastics vs. Natural Materials

The use of macromolecules or polymers has accompanied the entire human history. The most common polymers known today are called plastics and they are truly indispensable in everyday life. Their world production was about 230 million t in 2009, with virtually all of them made from natural gas or petrolemn. The stmctures of polymers resemble an extremely long pearl rope. This is a somewhat simphlled picture as the pearls may occasionally be quite different and the forces holding them together might also vary (Fig. 4.29). 

The first semisynthetic polymer, celluloid, was prepared by Alexander Parkes in 1855. Adolph Spitteler and W. Kirsch prepared plastic from milk protein (casein) and formaldehyde in 1899. Buttons, handles, pens and piano keys were made from the new material and it was patented under the name Galalith (aka Erinoid in the United Kingdom). Fully synthetic Bakehte was fist formulated by Leo Hendrik Baekeland (1863-1944) in 1907, and the age of plastics began with the discovery and large-scale industrial production of vulcanized rubber (1910), PVC (1926), polystyrene (1931), synthetic robber (1931-1935), polyethylene (1933), nylon 

Origin Plastic (abbreviation) Estimated world production (million t, 2008) Recycling code(s) 

What makes artificial plastics so attractive compared with long-used natural polymers such as wood, paper, cotton, wool, silk, horn, or natural rabber (caoutchouc) Synthesized plastics can be easily formed into almost any shape, they are resistant to environmental effects, heat, chemicals, and they are inexpensive (these properties, of course, differ depending on the type of plastics). Natural polymers have some advantages, too, primarily that they are typically more biodegradable than synthetic materials. As environmental pollution worsens, this property is becoming increasingly important. Humankind must use resources efficiently and must try to prevent unnecessary problems in the enviromnent. 

Polylactic add is indeed attractive for certain purposes, because the energy needed in its production from fossil fuels is about 30% less than for other plastics. It has disadvantages, though. It does not tolerate heat as well and is about 30% more expensive that common plastics that can be used for the same purpose. The price issue has legal aspects as well— no environmental taxes must be paid for products made of polylactic acid. 

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