Purity Requirements for Recycled Monomers and Oligomers in Photocurable Formulations: Inhibitors, Colour and Cure

Recovered monomers and oligomers can match the nominal identity of virgin photopolymer feedstocks while carrying inhibitors, chromophores, catalyst residues, water, degradation fragments or altered functionality that shift cure behaviour. Circular photopolymer manufacturing therefore needs acceptance criteria that connect chemical purity to optical response, polymerisation kinetics and final network properties. This review defines a qualification framework for recycled liquid feedstocks, including identity, impurity profile, colour and absorption, inhibitor balance, water and volatile content, functionality, cure response and lot-to-lot control. ER-456.