Preparation And Mechanism Of Free-Radical/Cationic Hybrid Photosensitive Resin With High Tensile Strength For Three-Dimensional Printing Applications

A ultraviolet (UV)-curing free-radical/cationic hybrid resin is designed and developed by blending epoxy resin with an acrylic resin, including N-acryloyl morpholine, polyurethane acrylic ester (PUA), free-radical and cationic photoinitiator. During UV-curing, crosslinking locks the acrylate and epoxide polymers together through non-covalent interaction. Most likely, the interpenetrating polymer network (IPN) structure can be generated in the three-dimensional (3D)-printed objects. The obtained results from Fourier transform infrared spectroscopy (FT-IR) show that bisphenol A epoxy resin and acrylic resin are both successfully involved in the UV-curing process. In addition, the effects of the mass ratio of epoxy to acrylic resin and the UV irradiation time on the properties of the hybrid resin are systematically investigated using liquid crystal display (LCD) 3D printers. It is found that the tensile strength of the hybrid resin increases in a certain range and the elongation at the break maintains an upward trend with the increasing mass ratio. Finally, it is found that the shrinkage of the hybrid resin also depends on the mass ratio of epoxy to acrylic resin, which decreases with the increase of the epoxy resin content in a certain range. Thus, herein we propose a feasible UV-curing mechanism for the synthesis of hybrid resins for 3D printing applications.