Material Library: Thermosetting Plastics

Thermosetting plastics:

(see plastics page)

		Thermosetting Plastics are plastics that can't be reshaped
		Just as a raw egg has the potential to become a boiled egg, a fried egg, and so on, thermosetting polymers have the potential to become all sorts of different objects. Once an egg has been boiled, however, you can't make it into a fried egg. In the same way, once a thermosetting plastic object has been formed, it can't be remade into a different object.
		The linear chains are crosslinked - strongly chemically bonded. This prevents a thermoplastic object from being melted and reformed.
		Thermosets are produced in two steps: 1. Linear polymers are formed. 2. The linear polymers are forced into a mold where "curing" takes place. This may involve heating, pressure, and the addition of catalysts. During this process, a cross-linked or networked structure forms, creating a permanently hard object that is no longer meltable or moldable.
		Thermosets are good to use for things that will be warmed up such as spatulas and other kitchen tools. They're also used in glues, varnishes, and in electronic components such as circuit boards.
		Thermosets are hard to recycle, but today there are methods of crushing the objects into a fine powder form for use as fillers in reinforced thermosets.

Here are a couple of simple things that people can consider to help improve the environment:
• Recycle plastic products when they reach the end of their useful life.
• Carry groceries in reusable bags.

Better catalysts improve plastics

For most applications, the ideal polymer is a long, straight chain with a highly regular molecular structure. Early synthetic polymers, however, often exhibited odd little branches and other irregularities. In the 1950s, German chemist Karl Ziegler (1898–1973) discovered that an entirely different type of catalyst - a combination of aluminum compounds with other metallic compounds - could solve some of these annoying problems and increase the length of a polymer chain, producing superior plastics. Ziegler became a wealthy man as a result of patents for plastics such as high density polyethylene (HDPE), which is used to manufacture a variety of products such as bottles or pipe.

Bakelite telephone:

Bakelite:

Bakelite is a versatile thermosetting plastic material which changed the manufacture of mass produced small consumer goods. It was widely used in commercial and industrial settings especially for electrical fittings and appliances because of its great insulating and heat resisting qualities.