In various embodiments, a resin composition includes a urethane (meth)acrylate, a reactive diluent, and a urethane (meth)acrylate toughener. The urethane (meth)acrylate toughener includes at least one additional polyol having a number average molecular weight Mn of greater than 1,000 g/mol. Cured articles made from the resin composition have an average fracture toughness (KIc) value from 1 MPa*m1/2 to 3 MPa*m1/2 when measured in accordance with ASTM D5045. Processes for making the resin composition as well as processes using the resin composition are also provided.