What is the difference between plastics and polymers?

The terms “plastics” and “polymers” are two ways of referring to overlapping material categories. Simply put, all plastics are polymers, but not all polymers are plastics.

Polymers are materials that consist of repeating chains of monomers (which are small, basic molecular building blocks that can “polymerize” into more advanced molecules). For example, natural monomers such as amino acids can polymerize into proteins, and synthetic polymers such as ethylene can polymerize into polyethylene.

Plastics are one type of engineered, man-made polymers, produced out of synthetic or semisynthetic chains of carbon atoms (monomers) mixed with additives, fillers, colorings, and/or other functional ingredients. In industrial use, plastics can be both a feedstock (raw material) and a finished product, such as with a “plastic pellet” being blow-molded into a “plastic bottle”.