   the reader is advised to begin with the article  see
chemistry of industrial polymers  , chemistry of   The
composition, structure, and properties of plastics       For the
purposes of this article, plastics are primarily defined not on
the basis of their chemical composition but on the basis of
their engineering behaviour. More specifically, they are defined
as either thermoplastic resins or thermosetting resins. This
fundamental distinction is seen in the organization of Table
1the table, and its origin in the chemical composition and
molecular structure of plastic polymers is described below.  The
polymers  Polymers are chemical compounds whose molecules are
very large, often resembling long chains made up of a seemingly
endless series of interconnected links. As The size of these
molecules, as is explained in chemistry of industrial polymers,
chemistry of, the size of these molecules is extraordinary,
ranging in the thousands and even millions of atomic mass units
(as opposed to the tens of atomic mass