Soybean oil monoglycerides (SOMG), obtained by the glycerolysis of soybean oil, were reacted with maleic anhydride to produce SOMG maleate half esters. The copolymers of the SOMG maleates, with styrene produced rigid thermosetting polymers. The dynamic mechanical analysis (DMA) of this polymer showed a glass-transition temperature (T-g) around 133 degreesC and a storage modulus (E') value around 0.94 GPa at 35 degreesC. The tensile tests performed on this polymer showed a tensile strength of 29.36 MPa and a tensile modulus of 0.84 GPa. Mixtures of SOMG with neopentyl glycol (NPG) and SOMG with bisphenol A (BPA) were also maleinized under the same reaction conditions and the resulting maleates were then copolymerized with styrene. The resulting polymers were analyzed for their mechanical properties. The T-g of the copolymers of the SOMG/NPG maleates with styrene was 145 degreesC and the E' value at 35 degreesC was 2 GPa. The tensile strength of this polymer as calculated from the stress-strain data was 15.65 MPa and the tensile modulus was 1.49 GPa. The T-g of the copolymers of SOMG/BPA maleates, on the other hand, was found to be around 131 degreesC and the E' value was 1.34 GPa at 35 degreesC. The changes observed in the mechanical properties of the resulting polymers with the introduction of NPG maleates and BPA maleates to the SOMG maleates can be explained by the structural changes on the polymer backbone.