A polymer is a molecule, made from many joining smaller molecules called monomers. The word “polymer” can be broken down into “poly” (meaning “many” in Greek) and “mer” (meaning “unit”). On this page: Conversational Nylon Types of Nylon What is Crystallinity? Viscosity Extractables Moisture Content Summary Base Resins Overview Fillers, Reinforcements and Additives Comparison of Filler or Additive Physical Properties