Method to analyse energy and intensity dependent photo-curing of acrylic esters in bulk

Abstract

The analysis of the photo-induced polymerization of bulk materials is a very important aspect of scientific and industrial research and applications. Thereby, the interactions between the initiator, the monomer and the light source have to be considered, which have been hardly/not investigated. For example, novel UV-light sources based on LED technology are in the process of development. Hence, the need for such kinetic analyses increases to investigate the multiple energy and intensity dependent influencing factors, like the quantum yield of the primary radical formation and the reactivity’s towards double bonds or inhibitors. Within this contribution a dose and wavelength dependent procedure is firstly described in detail, which allows the analysis of the kinetics of the photo-curing and the solidification of multifunctional liquid acrylic esters without a solvent. The photo-polymerizations induced by three different model resins, containing well-known commercial initiators, are monitored by an in situ Raman UV-vis system and analysed in detail. This novel procedure is based on an absolute and spectral calibrated fibre optical receiver, which is part of the Raman UV-vis setup. The multiple influences of the absorbed photons on e.g. the kinetic length of the chain reaction are presented and/or demonstrated. For example, higher yields can be achieved by less energetic and less intense irradiation.