Abstract: The diallyl phthalate (DAP) resin was toughened by two kinds of vinyl ester oligomers (VEO1 and VEO2) with different molecular weight. The gel time of the mixed resins and the insoluble fraction of the cured samples were measured. The cured samples were characterized by static mechanical testing, Dynamic Mechanic Analysis (DMA), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM). The results show that the impact strength increases by 73% with 5% VEO1 and by 120% with 20% VEO1, as well as the increment of flexural strength and the enhancement of thermal property. As a toughener for DAP resin, the VEO2 with higher molecular weight, is more advantageous.

Key words: vinyl ester oligomer, dialyl phthalate, toughening, flexural strength, thermal property