Ionising-Radiation Ageing of Printed Photopolymers: Dose, Atmosphere, Chain Scission, Crosslinking and Property Change

Ionising radiation deposits energy throughout polymer networks and can drive both chain scission and additional crosslinking. Which process dominates depends on backbone chemistry, dose, dose rate, oxygen availability, temperature, crystallinity or network heterogeneity, fillers and residual species. Printed photopolymers add spatial cure gradients and interfaces that may respond differently from homogeneous bulk specimens. Consequently, a single retained tensile-strength value after irradiation cannot identify mechanism or guarantee dimensional, dielectric or fracture performance. ER-387 requires the radiation field and atmosphere to be declared, distinguishes chemistry change from property change, and uses dose-series measurements to identify whether embrittlement, softening, swelling, mass change or interfacial degradation controls the service limit.