ABSTRACT
This chapter introduces different vat photopolymerization processes. Stereolithography (SLA) is one of the oldest and best-known examples of such processes and is popular to the extent of it being used synonymously with the vat polymerization process itself. International Organization for Standardization/American Society for Testing and Materials defines this process as: “Vat photopolymerization is an additive manufacturing process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization”. Vat photopolymerization processes use plastics as well as polymeric materials, especially UV-curable photopolymeric resins. An example of resins used with these processes is the Visijet range. Photoinitiators (PIs) are reactive to light. Irradiation of PIs with lights of the right wavelength leads to their excitation and thus initiation of the curing reaction. Correct choice of PI is therefore important and also depends on precursor type. It also effects a number of important SLA characteristics including kinetics, cross-linking density and mechanical characteristics to name a few.
