Relationship between physical-mechanical properties and glass transition temperatures of UV-cured polymers

A urethane acrylate oligomer (LR 8739) was used in combination with functional monomer diluents and codiluents possessing different glass transition temperatures (T-g's) to prepare thin polymer films under ultraviolet (UV) radiation. The amount of photoinitiator (Irgacure 184) and radiation dose intensity were optimized. The UV-cured films prepared at the optimized parameters were characterized to determine pendulum hardness, gel content, and tensile properties; these properties were correlated with glass transition temperatures of the UV-cured polymer films. The T-g values of the film were calculated on the basis of the Fox equation. The effect of codiluents on these properties was also investigated in consideration of the T-g values of the polymeric films prepared in the presence of codiluents.