THE EFFECT F EXTENDERS ON PHYSICOMECHANICAL CHARACTERISTICS OF EPOXY POLYMERS AND COMPOSITES BASED ON EXTENDED POLYMERS

The effect of extenders on the properties of epoxy polymers and epoxy-based composites was investigated. Three types of extenders were studied, the reactive one, which is chemically incorporated into polymer network (diglycidyl ether of diethylene glycol), inert (dibutyl phthalate), and a surfactant containing double bonds and capable to polymerize in the course of curing. All the extenders in low concentrations were shown to improve rheological characteristics of polymer, enhance elastic modulus of cured polymer, yet reduce its ultimate strain and strength. The inert extender causes a decrease in adhesive and tensile strength of the composites based on extended polymer, whereas reactive extender and surfactant in certain concentrations not only do not affect those but even somewhat enhance strength of composites. A possible explanation based on the concept of phase separation of components in the course of curing and modification of interphase boundary is proposed for the effect.