Epoxy toluene oligomers (ETO) are very important substances due to effective functional groups in their structure and they are especially used as polymer additives that have been synthesized from toluene and epichlorhydrin. Flame-retardant properties of the neat epoxy resin (ER), ETO, and ETO/ER blend thermoset were evaluated by UL94 vertical flammability test. The chlorine atoms in ETO increase the stability of the polymer material against burning. For the synthesis other polymers, first the waste product of the industrial vegetable oil refinement acid oil was transformed into the glycidyl ester (FAGE). Unsaturated oligo(ether-ester) (OEE) was prepared by ring-opening polymerization of the propylene oxide (PO) with FAGE in the presence of cationic catalyst BF3·O(C2H5)2. Its chemical structure was characterized with FTIR spectroscopy. These polymers, isoamyl methacrylate (AMA) and 1,2-epoxy-hexane-5-en (EH) were used as modifiers in the DGEBA-type epoxy resin. The effects of the modifier structure and amount on the mechanical properties of epoxy were investigated. Tensile strength and Young’s modulus of the modified samples were found higher than those of the neat epoxy resin.