Thermoset plastics are materials that melt initially but on further heating become permanently
hardened. They cannot be softened and remolded without destruction of the polymer because
covalent bonds are broken. Chemically, thermoset plastics are cross-linked polymers. Bakelite is
an example of a thermoset plastic.
Polymers can also be classified in other ways; for example, based on their uses, many varieties of
rubber are often referred to as elastomers, Dacron is a fiber, and polyvinyl acetate is an adhesive. The
chemical based classification will be used in this essay.