ABSTRACT
Organic and inorganic polymers are extremely versatile materials. Polymer properties are affected by several polymerization conditions such as the purity of the monomers, cure schedule, type and quantity of catalyst or initiator, stoichiometry of the comonomers, molecular weight of the polymer, and degree of crosslinking. The monomers currently used in the manufacture of all the commercially available polymeric compositions, such as potting and casting resins, molding resins, films coatings, etc., exhibit some degree of shrinkage during manufacturing and processing. In molding applications, polymer shrinkage results in incomplete filling of the mold and poor replication of the mold surface. Polymerization shrinkage is produced during the basic polymerization process. In general, as a monomer polymerizes, its density changes as a direct result of the bond changes being affected during polymer formation. Three types of polymerization processes are used to convert monomers into polymers. They are chain-growth polymerization, step-reaction polymerization, and ring-opening polymerization.
