Polymerization Reactions is chemical reaction in which high molecular mass  polymerization molecules are formed from monomers.The formation of a free radical from an organic peroxide is shown belowPolymers produce from this polymerization (polymethyl methacryliate(PMM),ethylene oxide (PEO),polypropene (PP) Ethylene is one example of a monomer used to make a common polymer.In chain-reaction polymerization, the catalyst can be a free-radical peroxide added in  relatively low concentrations.)Reaction Polymerization-Chain(Polymerization  AdditionA)  One of the most common types of polymer reactions is chain-reaction (addition) polymerization.