A natural or synthetic compound, usually of high molecular weight with a long-chained structure that consists of repeated linked molecular units called monomers or mers.
Monomers are relatively light and simple. A chemical polymerization process builds polymers from monomers.
Although the term plastics is often used as a synonym for polymer, plastics are actually one type of polymeric compound. Plastics are generally formulated with plasticizers, stabilizers, fillers, and other additives for the purpose of processing and performance.
Non-plastic polymeric systems include rubbers, fibers, adhesives, and surface coatings.
Processing polymers into end products involves physical changes such as melting and solidification for thermoplastics or chemical reactions for thermosets.