In order to study the effect of the addition of MEPECO to VE in terms of mechanical properties, the change in flexural strength and flexural modulus of Vinyl Ester (VE) resin were evaluated upon the addition of MEPECO at different loading percentages, which are as follows: 0%, 1%, 3%, 5%, and 7%. Figure (a) demonstrates and agrees with the flammability property result that the optimal additive loading was at 5% MEPECO. The VE_5% MEPECO increased the flexural strength of VE by about 14.93%, or 82.68 MPa. The increase in flexural strength might be because of an effective reinforcing agent; at 5%, it enhanced the structural integrity of the resin matrix. The possibility of homogeneous dispersion and distribution of 5% MEPECO over vinyl ester resin molecules to fill in the void and microcracks might produce an effective filler-matrix interaction leading to improved strength. Another possibility is that the addition of 5% MEPECO improved the crosslinking density of the epoxy resin and caused certain changes in the vinyl ester resin, regardless of the phase structure. However, the apparent decrease in flexural modulus of about 10.39%, or 3.586 GPa, might be because of the uncontrollable lower elastic modulus of 5% MEPECO, which can lead to a decrease in the overall stiffness of the composite. Figures and) support the result, as VE_5% MEPECO tends to withhold higher stress and load capacity, resulting in higher flexural strength.