High Toughness Resin Cured by UV Light for Trenchless Pipeline Repair

In ultraviolet cured-in-place-pipe (UV-CIPP) pipeline rehabilitation, resin performance critically determines repair effectiveness. Current UV-curable resins exhibit high volatile organic compound (VOC) emissions and inadequate post-cure toughness, which compromise fatigue resistance during service. To address these issues, we synthesized hydroxyl-terminated polyurethane acrylate prepolymers using diphenylmethane diisocyanate (MDI), polypropylene glycol (PPG), and hydroxyethyl methacrylate (HEMA). Fourier transform infrared spectroscopy (FTIR) confirmed successful prepolymer synthesis. We developed UV-curable resins by incorporating various crosslinking monomers and optimized the formulations through mechanical property analysis. Testing revealed that the polyurethane–acrylic UV-cured resin system combines polyurethane’s mechanical excellence with acrylics’ high UV-curing activity. The PPG200/MDI/HEMA formulation achieved superior performance, with a tensile strength of 55.31 MPa, an impact toughness of 22.7 kJ/m 2 , and a heat deflection temperature (HDT) of 132 °C. The optimized system eliminates volatile components while maintaining high reactivity, addressing critical limitations in trenchless pipeline rehabilitation. The improved mechanical properties meet the operational demands of underground pipes, suggesting practical applicability in trenchless pipeline repair.