A plastic material is any of a wide range of synthetic or semi-
synthetic organic solids that are moldable. Plastics are
typically organic polymers of high molecular mass, but they
often contain other substances. They are usually synthetic, most
commonly derived from petrochemicals, but many are partially
natural. Most plastics contain organic polymers. The vast
majority of these polymers are based on chains of carbon atoms
alone or with oxygen, sulfur, or nitrogen as well. The backbone
is that part of the chain on the main "path" linking a large
number of repeat units together. To customize the properties of
a plastic, different molecular groups "hang" from the backbone
(usually they are "hung" as part of the monomers before the
monomers are linked together to form the polymer chain). The
structure of these "side chains" influence the properties of the
polymer. This fine tuning of the properties of the polymer by
repeating unit's molecular structure has allowed plastics to
become an indispensable part of the