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The Business of Bioplastics

  • Teacher Resource
  • Posted 01.12.12
  • NOVA

In this video excerpt from NOVA's "Making Stuff: Cleaner", host and New York Times technology columnist David Pogue visits a Ford factory, where petroleum-based plastics in cars are being replaced with cleaner bioplastics. Watch how wheatgrass bioplastic for the Ford Flex is produced and helps conserve about 30,000 pounds of petroleum every year. In the related demonstration, students learn that bioplastics, made from plant or animal products, are cleaner than petroleum-based synthetic plastics because they can break down more easily in the environment. Students can follow a simple recipe to make their own bioplastic in a process similar to cheese making.

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NOVA The Business of Bioplastics
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  • Media Type: Video
  • Running Time: 2m 01s
  • Size: 7.2 MB
  • Level: Grades 6-12

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This media asset was adapted from NOVA's "Making Stuff: Cleaner".

Background

Each year, we extract some 30 trillion tons of raw materials from the Earth. We turn iron ore into steel cars, petroleum products into plastics, and metals into batteries. What happens to all those raw materials when the useful life of our stuff ends? Many end up in landfills or at the bottom of rivers, lakes, and oceans.

The word plastic has many meanings. In everyday language, it means a materials or object that can be molded or shaped. Such materials have the property of plasticity. Scientifically, however, a plastic is a type of polymer, a substance made of long chains of molecules. The properties of a plastic – whether it bends or stretches, remains soft or hardens into a solid – depend on how those long chains are arranged.

Polymers, including plastics, can be synthetic or natural. Today most plastics are synthetic and made from petroleum. It can take hundreds of years or more for light, heat, or moisture to break them down in the environment. When they do degrade, some can leach harmful substances into the water or soil. However, bioplastics are usually biodegradable, which means they will decay as microbes eat them.

This presents a challenge to materials scientists who must design materials that are strong and durable enough to be useful – but not so strong and durable that they remain in the environment long after they are no longer needed.

One type of bioplastic is made from the protein found in milk, called casein (pronunciation: “kay-seen”). Casein plastic, invented in 1899, is made by a process similar to cheese making in which an acid is added to milk. This causes the casein proteins to unfold and reorganize into long chains of molecules forming a polymer. This process is called polymerization.

In the early 20th century, before petroleum-based plastics became widespread and relatively inexpensive to produce, casein plastic was used to make jewelry, buttons, door handles, and acrylic paints. Today it is a component of some glues. Another, harder form of casein plastic, called galalith, which means “milkstone” in Greek, is produced by adding formaldehyde, which is a toxic chemical.

Resource Produced by:


					WGBH Educational Foundation

Collection Developed by:


						WGBH Educational Foundation

Collection Funded by:


						National Science Foundation

						U.S. Department of Energy



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