Electron-beam initiated polymerization of acrylate compositions 3: compared reactivity of hexanediol and tripropyleneglycol diacrylates under UV or EB initiation

The radiation-induced polymerization of liquid films, including hexanediol diacrylate (HDDA) or tripropyleneglycol diacrylate (TPGDA), was investigated by means of transmission infrared spectroscopy. Electron-beam (EB) and ultraviolet (UV) irradiations were performed and the reactions were monitored to examine the influence of the nature of the difunctional monomer on its polymerization rate, depending on the initiation mode. By UV-initiation, with a 2-benzoylpropan-2-ol as photoinitiator, the polymerization profiles are very similar for the two monomers, thus indicating that the chemical nature of the difunctional monomer has no major effect on the reaction kinetics. Conversely, by EB-initiation, TPGDA appears clearly to be more reactive than HDDA, with an initial polymerization rate twice as large as that of HDDA. The same influence of the monomer structure on the reactivity was observed in acrylated polyurethane-monomer blends submitted to EB-irradiation, whereas UV-initiation leads to comparable polymerization profiles. This behavior is presumably due to the particular structure of the spacer linking the acrylate function in TPGDA