TABLE OF CONTENTS Are organic chemical compounds of high molecular weight that have a structure resulting from the repeated linking together of small molecules, called monomers. The resulting long-chain molecules are polymers. Plastics are one type of polymer; elastomers (rubber-like materials) are another. Polymers can be either natural or synthetic. The molecular weight of the polymer is a multiple of the molecular weight of the monomer. Usually, at least 100 monomer molecules and up to many thousands of monomer molecules may be incorporated in one molecule of a polymer or elastomer.
There are two basic types of plastics, thermo-plastics, which soften and melt when heated (melting takes place over a wide temperature range) and thermosetting plastics, whose long molecules are crosslinked together. Thermosetting plastics do not melt upon heating but remain rigid until they reach the charring or burning temperature.
Are the chemical reactions in which the individual, relatively small, monomer molecules link together into very long chains, called polymers. The two basic polymerization reactions are addition polymerization and condensation polymerization.
Is a simple combination of molecules without the release of any by-products. In one addition polymerization reaction, a chemical activation of the molecules with the aid of an initiator (a chemical catalyst or other substance), causes the atoms of the monomer molecules to bond together, creating chains of molecules. These chains may have as many as several hundred thousand repeating molecular units and...
