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 studi ed, the reactive one, which is chemically incorporated into polymer ne twork (diglycidyl ether of diethylene glycol), inert (dibutyl phthalat e), 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 elas tic modulus of cured polymer, yet reduce its ultimate strain and stren gth. The inert extender causes a decrease in adhesive and tensile stre ngth of the composites based on extended polymer, whereas reactive ext ender and surfactant in certain concentrations not only do not affect those but even somewhat enhance strength of composites. A possible exp lanation based on the concept of phase separation of components in the course of curing and modification of interphase boundary is proposed for the effect.