Physics-mechanical and viscoelastic properties of polymer compositions based on synthetic oligomer ED-20 and epoxidized soybean oil

Abstract

The work was aimed at studying the effects of combining epoxidized soybean oil (ESO) with standard bisphenol type A epoxy resin (ED-20). The ED-20 / ESO ratios were 100/0, 90/10, 95/15 and 80/20 (wt%). The system was cured with amine hardener mono(cyanethyl) diethylenetriamine (MCDT), triethanolamine (TEA) and mixture thereof (TEA + MCDT) at different curing temperatures. The choice was based on the hardener’s ability to open oxirane cycles, form a spatial network and initiate several parallel reactions. The viscoelastic properties, mechanical properties (tensile strength and elongation) were studied the density of obtained ED-20 / ESO samples was determined. The results showed that the introduction of ESO into epoxy resin ED-20 was accompanied by significant changes in the curing and final properties of the samples. It was shown that the physic- mechanical properties of polymer compositions ED-20 / ESO were determined by both the ESO content and the temperature of curing Depending on the selected curing mode, the addition of 5–10 wt.% of ESO increased the tensile strength relative to the σр value of the original epoxy matrix. The values of relative elongation increased significantly at 15-20 wt.% of ESO. By the method of dynamic mechanical analysis it was shown that the increase of ESO content leads to plasticization of epoxy composition and to reduction of crosslinking density. It was determined that 5-10 wt.% was the optimal concentration of ESO, at which the epoxy composition had improved physical and mechanical properties Further increase of ESO content reduced the crosslinking density and increased the defectiveness of the epoxy polymer, which causes premature failure in weak places of the structure under load.