Synthesis and polymerization of a new highly unsaturated castor oil‐based monomer for rigid thermoset materials

A new highly functionalized monomer (maleated castor oil methacrylate, MACOMA) was synthesized from maleated castor oil (MACO) and glycidyl methacrylate (GMA) through the epoxy–carboxyl reaction. This reaction led to a monomer with 8.8 double bounds per molecule and negligible acid value. Homopolymerization of MACOMA at room temperature led to a highly crosslinked elastomeric material ( T g , 15.98°C; flexural modulus, 77.7 MPa; flexural strength, 7.45 MPa and surface hardness, 46‐Shore D). On the other hand, homopolymerization of MACO led to viscous liquids even after prolonged heating. Curing of MACOMA‐styrene mixtures (20–50%) at room temperature for 4 h led to rigid materials: T g , 54.04–81.36°C; flexural modulus, 508.6–1254.3 MPa; flexural strength, 21.97–64.06 MPa; and surface hardness, 57–69 (Shore D). Mechanical properties of these materials were better than those of MACO‐styrene copolymers. Materials obtained from both resins were stable under 230°C. However, higher thermal stabilities were obtained for MACOMA‐based materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46762.