Modification of Epoxy Resin ED-20 with Copper and Ammonium Phosphates

Abstract

Modification of the epoxy diane resin ED-20 with 1.5 wt % copper(II) hydroxide–orthophosphate solutions (4 : 2 : 2) in phosphorous acid and in a mixture H₃PO₄ : (NH₄)₂HPO₄ = 10 : 1 (wt) and curing with triethylenetetramine results in the formation of crystalline phase of different structure and geometry but close chemical composition in the polymer. At the maximum modifier content 8 wt % the synthesized polymers are characterized by oxygen index values of 24.7–25.1 vol %. In addition, these polymers reach the category of resistance to burning PV-0 according to GOST 28157–89 (when the flame source is removed, the standard sample burns not more than 10 s and then independently extinguishes). The elastic modulus and bending breaking stress are 3.9 GPa and 53.3 MPa, respectively. The presence of ammonium hydrophosphate in the formulation leads to a decrease in initial viscosity values down to 48% and an increase in bending strength up to 2.5 times and heat resistance by 20–25°C.