Influence of curing conditions and dibutyl phthalate concentration on the properties of cured epoxy resin

The influence of the curing conditions and dibutyl phthalate additions on the physicomechanical properties of cured polyepoxides based on ED-20 resin and 4,4'-diaminodiphenylmethane curing agent was examined. An increase in the curing temperature over 150°С does not noticeably influence the physicomechanical properties of the cured resin, and keeping of the reaction mixture at 180°С for 12 h leads to a considerable decrease in the glass transition temperature of the polymer. Addition of dibutyl phthalate in concentrations of up to 10 wt % decreases the glass transition teperature of the polymer by 44°C, but with increasing concentration of dibutyl phthalate the elastic modulus increases and the breaking strain slightly decreases. The dependence of the ultimate strength on the dibutyl phthalate concentration passes through a maximum at 3 wt % dibutyl phthalate.